tag:blogger.com,1999:blog-39787214264892989382024-02-20T15:49:06.871-08:00OUTCROPThe blog of the Avon RIGS Group - promoting geology in the West CountryAvonhttp://www.blogger.com/profile/08529266455478858396noreply@blogger.comBlogger58125tag:blogger.com,1999:blog-3978721426489298938.post-16942302023641025842017-08-25T06:18:00.001-07:002017-08-30T04:06:46.823-07:00<span style="font-family: Arial, Helvetica, sans-serif;">"New exposures of our local geology are being seen, summer 2017, as work to put in new railway tracks between Bristol Temple Meads Station and Bristol Parkway, continues with some pace. David Moore photo-recorded this cutting into the Saltford Shale, Lower Jurassic strata, Monday 21st August from the Filton Abbeywood Station footbridge. (If one zooms in on photos perhaps fossils might be seen. Do let us, Avon RIGS Group, know, if you do.).".</span><br />
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<span style="font-family: Arial, Helvetica, sans-serif;">Thanks to David for his work.</span><br />
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<span style="font-family: Arial, Helvetica, sans-serif; font-size: medium;">The following information is from the BGS Lexicon of Named Rock Units.</span></div>
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<span style="font-family: Arial, Helvetica, sans-serif; font-size: medium;">http://www.bgs.ac.uk/lexicon/home.html</span></div>
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<span style="font-family: Arial, Helvetica, sans-serif; font-size: medium;">Accessed 21st August 2017</span></div>
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<h1 style="-webkit-font-smoothing: antialiased; color: #c95513; font-family: Verdana, Calibri, Arial, sans-serif; font-size: 34.959999084472656px; font-weight: normal; margin: 0px 0px 0.4em; padding: 0px;">
<span style="color: #013171; font-size: 22.799999237060547px;">Saltford Shale Member</span></h1>
<div class="sectionBody" style="font-family: Verdana, Arial, sans-serif; font-size: 15.199999809265137px; margin: 0px; padding: 0px;">
<table border="0" cellpadding="5" cellspacing="0" class="bodyTable" style="border-collapse: collapse; margin: 0.8em 0px 0.5em; padding: 0px; width: 100%px;"><tbody style="margin: 0px; padding: 0px;">
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;" width="18%">Computer Code:</th><td style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;" width="32%">SASH</td><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;" width="18%">Preferred Map Code:</th><td style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;" width="32%">SaSh </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Status Code:</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Full </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Age range:</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;"><a href="http://data.bgs.ac.uk/id/Geochronology/Division/TR" style="color: #c64027; margin: 0px; padding: 0px; text-decoration: none;" target="_blank">Rhaetian Age</a> (TR) — <a href="http://data.bgs.ac.uk/id/Geochronology/Division/JH" style="color: #c64027; margin: 0px; padding: 0px; text-decoration: none;" target="_blank">Hettangian Age</a> (JH) </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Lithological Description:</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Mostly grey, fissile or blocky, fossiliferous calcareous mudstones; a few limestones. </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Definition of Lower Boundary:</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Placed at the base of mudstones resting on the highest limestone of the underlying Wilmcote Limestone. Placed at top of Bed 26 at type section (Donovan, 1956). </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Definition of Upper Boundary:</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Placed at the base of an interbedded argillaceous limestone ('cementstone') and mudstone sequence. At base of Bed 22 at type section. (Donovan, 1956). </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Thickness:</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">4.27m at type section, 20-30m over most of Midlands. </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Geographical Limits:</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Central and southern Midlands. </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Parent Unit:</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;"><a class="bodyLink" href="http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=BLI" style="color: #c64027; margin: 0px; padding: 0px; text-decoration: none;">Blue Lias Formation</a> (BLI)</td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Previous Name(s):</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Angulata Beds (-2408)<br />
Psiloceras Shales (-4871) </td></tr>
<tr style="margin: 0px; padding: 0px;"><th style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Alternative Name(s):</th><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;"><em style="margin: 0px; padding: 0px;">none recorded or not applicable</em></td></tr>
<tr style="margin: 0px; padding: 0px;"><th colspan="4" style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Stratotypes:</th></tr>
<tr style="margin: 0px; padding: 0px;"><td style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;" width="15%">Type Section </td><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Section at Saltford railway cutting southeast of Keynsham, Somerset (Donovan, 1956, p.182-212). </td></tr>
<tr style="margin: 0px; padding: 0px;"><td style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;" width="15%">Reference Section </td><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">BGS Twyning Borehole, 82.25 to 114.80m depth. </td></tr>
<tr style="margin: 0px; padding: 0px;"><td style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;" width="15%">Reference Section </td><td colspan="3" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">BGS Stowell Park Borehole, 1932' 0" to 2028' 6" depth. </td></tr>
<tr style="margin: 0px; padding: 0px;"><th colspan="4" style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">Reference(s):</th></tr>
<tr style="margin: 0px; padding: 0px;"><td colspan="4" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Donovan, D T, 1956. The zonal stratigraphy of the Blue Lias around Keynsham, Somerset. Proceedings of the Geologists' Association, Vol.66, p. 182-212. </td></tr>
<tr style="margin: 0px; padding: 0px;"><td colspan="4" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;">Old R A, Hamblin, R J O, Ambrose, K, and Warrington G. 1991. Geology of the country around Redditch. Memoir of the British Geological Survey, Sheet 183 (England and Wales). </td></tr>
<tr style="margin: 0px; padding: 0px;"><th colspan="4" style="background-image: linear-gradient(rgb(138, 160, 198) 0%, rgb(1, 49, 113) 40%); background-position: initial initial; background-repeat: initial initial; border: 0.1em solid rgb(1, 49, 113); color: white; font-weight: normal; margin: 0px; padding: 0.5em; vertical-align: top;">1:50K maps on which the lithostratigraphical unit is found, and map code used:</th></tr>
<tr style="margin: 0px; padding: 0px;"><td colspan="4" style="background-color: white; border: 0.1em solid rgb(138, 160, 198); margin: 0px; padding: 0.5em; vertical-align: top;"><a class="bodyLink" href="http://shop.bgs.ac.uk/Bookshop/mapResults.cfm?MAP_TYPE=50K&SHEET_NO=E183" style="color: #c64027; margin: 0px; padding: 0px; text-decoration: none;" target="_blank">E183</a> <a class="bodyLink" href="http://shop.bgs.ac.uk/Bookshop/mapResults.cfm?MAP_TYPE=50K&SHEET_NO=E169" style="color: #c64027; margin: 0px; padding: 0px; text-decoration: none;" target="_blank">E169</a> <a class="bodyLink" href="http://shop.bgs.ac.uk/Bookshop/mapResults.cfm?MAP_TYPE=50K&SHEET_NO=E199" style="color: #c64027; margin: 0px; padding: 0px; text-decoration: none;" target="_blank">E199</a> <a class="bodyLink" href="http://shop.bgs.ac.uk/Bookshop/mapResults.cfm?MAP_TYPE=50K&SHEET_NO=E264" style="color: #c64027; margin: 0px; padding: 0px; text-decoration: none;" target="_blank">E264</a></td></tr>
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<br />Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-86072181209305019432017-06-10T06:43:00.001-07:002017-06-10T06:43:32.082-07:00Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-19795510514363936752017-06-10T06:28:00.001-07:002017-06-27T00:52:25.994-07:00Barnhill Gate Estate<span style="font-size: large;">Some images taken on the Barnhill Gate Estate showing the houses and the geological exposures of the faces of the old Barnhill Quarry.</span><br />
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<span style="font-size: large;">" A room with a geological view "</span></h2>
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<span style="font-size: medium;">Photo credits David Moore</span></div>
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-48363745979633824942016-11-05T07:23:00.001-07:002016-11-19T06:01:27.360-08:00<h3 class="post-title entry-title" itemprop="name" style="color: #333333; font-family: Arial, Tahoma, Helvetica, FreeSans, sans-serif; font-size: 18px; line-height: normal; margin: 0px; position: relative;">
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<a href="http://avonrigsoutcrop.blogspot.co.uk/2012/06/south-gloucestershire-geology-booklet.html" style="color: #9900ff; text-decoration: none;"><span style="font-size: large;">South Gloucestershire geology booklet - free download</span></a></h3>
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<b><i>The story of geology & landscape in South Gloucestershire</i></b> was published in April 2007 hard copy format as a collaboration between <a href="http://www.southglos.gov.uk/NR/exeres/93e02326-a91e-425a-8ef1-09ab21a85f0b" style="color: #9900ff; text-decoration: none;">South Gloucestershire Council</a>, the <a href="http://avonrigsoutcrop.blogspot.co.uk/p/about-avon-rigs.html" style="color: #9900ff; text-decoration: none;">Avon RIGS Group</a>, <a href="http://www.brerc.org.uk/" style="color: #9900ff; text-decoration: none;">BRERC</a> and <a href="http://www.bristol.gov.uk/page/geology-museum-collection" style="color: #9900ff; text-decoration: none;">Bristol Museum</a>. Although paper copies are no longer available, this excellent thirteen page booklet is still available as a free-to-download pdf below. </div>
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<tr><td class="tr-caption" style="font-size: 11.880000114440918px;"><b><span style="font-family: "verdana" , sans-serif; font-size: xx-small;">Front cover</span></b><br />
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Click <a href="http://www.brerc.org.uk/downloads/journey-across-400-million-years.pdf">Booklet</a> to download in PDF format.</div>
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<attachment webkitattachmentpath="/Users/richard/Desktop/A journey across 400 million years.pdf"></attachment> <attachment webkitattachmentpath="/Users/richard/Desktop/A journey across 400 million years.pdf"></attachment> <attachment webkitattachmentpath="/Users/richard/Desktop/Mountains and Coral Seas Barnhill Quarry.pdf"></attachment> </div>
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Fourteen local sites, including <a href="http://avonrigsoutcrop.blogspot.co.uk/2012/06/rigs-of-month-june-aust-cliff.html" style="color: #9900ff; text-decoration: none;">Aust Cliff</a>, Huckford Quarry and Wick Golden Valley are featured. Each outcrop is described and interpreted with cross sections, location maps and annotated photos. </div>
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<span style="font-family: "verdana" , sans-serif;"> JPEGs of the site interpretation panels in South Gloucestershire can be accessed using </span></div>
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<span style="font-family: "verdana" , sans-serif;">these links:-</span></div>
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<span style="font-family: "verdana" , sans-serif;"><br /></span><span style="font-family: "verdana" , sans-serif;"><br /></span><span style="font-family: "verdana" , sans-serif;">The archive of the paper copies of OUTCROP can be accessed by clicking <a href="http://www.brerc.org.uk/downloads/outcrop16.pdf">Here</a> . This will take you to Issue 15. Later issues can be seen by clicking on the links below.</span></div>
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<span style="font-family: "verdana" , sans-serif;"><br /></span><a href="http://www.brerc.org.uk/downloads/outcrop16.pdf">Issue 16</a></div>
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<a href="http://www.brerc.org.uk/downloads/outcrop17.pdf">Issue 17</a></div>
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<a href="http://www.brerc.org.uk/downloads/outcrop18.pdf">Issue 18</a></div>
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<a href="http://www.brerc.org.uk/downloads/outcrop19.pdf">Issue 19</a> </div>
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<a href="http://www.brerc.org.uk/downloads/outcrop20.pdf">Issue 20</a></div>
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-54355436317652348052016-05-24T06:02:00.000-07:002016-05-25T08:56:39.459-07:00Geology Trail in Badgers Wood Nature Reserve<div class="leading-0" style="border: 0px; color: #555555; font-family: Helvetica, Arial, sans-serif; font-size: 13px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">
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<span style="-webkit-font-kerning: none;"><b>Backwell Environment Trust</b></span></div>
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<span style="font-kerning: none;">BET was founded in 2004 to protect and preserve the beautiful countryside surrounding the historic village of Backwell, North Somerset. We presently own and manage two nature reserves comprising nearly 22 acres in area. Both reserves contain many rare and endangered species and have a facinating history dating back at least 5,000 years</span></div>
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<span style="font-kerning: none;"><b>BET's Nature Reserves</b></span><br />
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<span style="font-kerning: none;">Our two reserves are the 10-acre <b>Jubilee Stone Wood</b> and the 12-acre <b>Badgers Wood</b>. Both reserves are located to the south-east of Backwell, high up on Backwell Hill and offer free access to the whole community. There are sections of level, wheel-chair friendly paths in both reserves leading to magnificent viewpoints taking in the Bristol Channel, Wales and Exmoor on clear days.</span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtvDxebQhPRHbZjEczGMEvMX43ER8aF0rmhEDHMkdgTLDdhmysXQXbSqxw0Y8k2GR1YbdLueUw1p_uXjS9C7CwBh8t1OiFETq_sQGPb5_iVTNwj48cN0QWwwQHAB6i7_Re4ci8LhjozjhX/s1600/Our_Reserves.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="247" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtvDxebQhPRHbZjEczGMEvMX43ER8aF0rmhEDHMkdgTLDdhmysXQXbSqxw0Y8k2GR1YbdLueUw1p_uXjS9C7CwBh8t1OiFETq_sQGPb5_iVTNwj48cN0QWwwQHAB6i7_Re4ci8LhjozjhX/s400/Our_Reserves.jpg" width="400" /></a></div>
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<span style="-webkit-font-kerning: none;">They serve as public amenity woodlands, an educational resource as well as being a superb location for wildlife. Together the two nature reserves cover almost 22 acres in area and are a mixture of broadleaf woodland interspaced with open areas of calcarious grassland. Its many rare species include the Hazel Dormouse, Greater Horseshoe Bat and the Yellow Bird's-nest plant.</span></div>
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<span style="-webkit-font-kerning: none;">The reserves have an amazing archaeological history and contain the ruins of a 14th century rabbit warren and cottage, 17th century lead mines and a (now restored) 19th century limekiln.</span></div>
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<span style="-webkit-font-kerning: none;">Downloadable maps of the trails in the reserves can be seen at:-</span></div>
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<a href="http://backwellenvironmenttrust.org/index.php/bet-bulletins/maps" style="font-family: Calibri; font-size: 16px; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-ligatures: normal; font-variant-numeric: normal; font-variant-position: normal; line-height: normal; text-align: start;" title="http://backwellenvironmenttrust.org/index.php/bet-bulletins/maps">http://backwellenvironmenttrust.org/index.php/bet-bulletins/maps</a><br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">Backwell Hill, where the BET nature reserves are located, is part of an anticlinal structure which forms a dome called Broadfield Down. The two reserves are on the North facing slopes of the Down. The topography of the Down follows the underlying stratigraphy, as can be seen in the face of the disused Coles Quarry from the access path viewpoint.</span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif; text-align: justify;"><span style="font-size: x-small;">Photo credit David Moore</span></span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="font-kerning: none;"></span>View into Coles Quarry and across to Wales from the access path view point.</span></div>
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<span style="font-kerning: none;"><b><span style="font-family: "arial" , "helvetica" , sans-serif;">A geological history of Broadfield Down</span></b></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The oldest rocks that can be seen exposed in this area are the Upper Old Red Sandstones which were laid down between 380 and 360 million years ago ( mya ) during the Devonian geological period. ( 420 – 360 mya )</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The part of the British Isles that includes Broadfield Down was then drifting slowly North from 20 - 25 degrees South of the equator. It was part of a tectonic plate that included the continents of Baltica and Laurentia. This plate was separated from another plate called Gondwana by the Rheic Ocean. </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Gondwana included the future continents of Africa, South America and the rest of Europe and Asia. Scotland and England had been recently united by a collision between the plates of Laurentia and Avalonia. This collision closed the Iapetus Ocean and caused a wrinkling of the Earth’s crust which resulted in a mountain building process called the Caledonian Orogeny. In Greek mythology Iapetus was the father of Atlas for whom the Atlantic ocean was named, so the Iapetus ocean can be seen as the precursor of the Atlantic.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">These massive mountains are called the Caledonides and, as they started being quickly eroded, the material produced was carried South by massive meandering river systems in an arid continental, desert environment. This material was laid down and lithified to form sandstone beds which are known as the Upper Old Red Sandstone. The name comes from the red-brown colour from the oxidised iron, haematite, coating on the quartz grains. Within the Old Red Sandstone are fine grained mica-rich sandstones, shales and mudstones.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">These rocks form the cores of the Mendips, Broadfield Down and Failand Ridge. They are known as the Portishead Beds and can be seen exposed along the coast between Clevedon and Portishead. There are also some small exposures in the bed of the track that drops down from Cadbury Camp Lane under the motorway to join Clapton Lane near the Black Horse pub.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The Devonian period came to an end about 360 million years ago ( 360 mya ). At the start of the following Carboniferous period ( 360 – 300 mya ) all the continents had moved together, adding Laurentia and Gondwana, closing the Rheic Ocean. The British Isles were now moving slowly northwards across the equator into the northern tropics. Shallow seas started to cover the Devonian desert.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Various limestones were deposited in these warm, shallow seas. Some of these limestones are oolitic – consisting of small, < 2mm, egg-shaped particles called ooids. Because they were shallow and warm, there was a high evaporation rate which made the seawater supersaturated.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">These were formed in a similar way to rolling snowballs. Calcium carbonate accreted around a particle, of shell or sand, and the ooids grew in size as they were rolled around the sea floor in the lime saturated water. This process now continues in the Bahamas.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">One of these limestones is Clifton Down Limestone which forms the crags alongside which the Geological Trail was built.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Many of these limestones contain fossils, crinoids, corals and brachiopods, and are very common in this area. Fossils can be seen where the host limestones were used for building, such as in the walls along Stockway North and in the parapets of Jackland’s Bridge in Nailsea and in the rocks used for building the drystone wall along the Northern side of Cadbury Camp Lane West, to the West of Cadbury Camp.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Not many of these fossils can be seen on Backwell Hill but an exception is an excellent specimen of <i>Siphondendron Martini ( Lithostrotion ) </i>that was found on a rock pile near the view point at the top of the trail during a geological field trip by the Bristol Naturalists. </span></span></div>
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<span style="font-kerning: none;"><i><span style="font-family: "arial" , "helvetica" , sans-serif;">Siphonodendron Martinin ( Lithostrotion )</span></i></span></div>
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<span style="font-kerning: none; text-decoration: underline;"><a href="http://avonrigsoutcrop.blogspot.co.uk/2012/06/lithostrotion.html"><i><span style="font-family: "arial" , "helvetica" , sans-serif;">http://avonrigsoutcrop.blogspot.co.uk/2012/06/lithostrotion.html</span></i></a></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The seas gradually shallowed so the formation of limestones stopped. Rivers brought material to the area and deposited quartzitic sandstones on top of the limestones. These are generally known as Millstone Grit.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The climate had changed from arid to equatorial conditions so the rivers increased in size and flow because of the increase in rainfall. Swamps started to form and the rivers formed deltas on the coasts. Primitive plants such as horse tails grew in these swamps and as they died, peat started to form. These swamps and deltas were periodically flooded as the sea level rose and fell. The rivers deposited material eroded from the high ground formed by the continuing orogeny which covered the peat with layers of sandstone. These sandstones compressed the peat which was slowly turned to coal. As the rivers meandered and moved away, plants started taking hold again and so there are repeated cycles of clay, coal and sandstone that can be seen in the Nailsea coalfield. The records of the Watercress Farm borehole, that was drilled in 1903 while looking for a water supply for Tyntesfield demonstrate this. These repeating cycles are called cyclothems. The clay is the relic of the soil that the plants grew in and is invariably found below a coal seam. Coal miners call this ‘seat earth.’ This clay is commonly used to line furnaces as ‘fire clay’ and would probably have been used in the Nailsea glass works’ kilns. It was also used to make bricks in, for example, the brick works that existed adjacent to the shafts of the Dean Lane coal mine in Southville.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The coal seams crop out at the surface on the northern slope of the Nailsea syncline and this is where mining probably started using drift mines to follow the seams. This area was surveyed in 1950 by the Coal Board to assess its viability for surface coal mining. Deep shaft mines followed later, towards the centre of the coalfield.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">William Smith – known as the ‘Father of Geology’ - carried out a survey for the mine owners in 1811 to see if the coal output would justify the building of a canal to take the coal to market. In his opinion it was and he sounded very optimistic in his report of 1811 and some of the necessary land was purchased but the canal was never built as the competition increased form the South Wales coalfield.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">As the Carboniferous period progressed, the Rheic ocean closed and so there was increasing tectonic pressure from the South West. This is called the Variscan Orogeny. It resulted in crustal folding in the area and formed the Mendips, Broadfield Down, Failand Ridge and the Nailsea syncline. It continued for some 100 million years into the Permian.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The rivers bringing erosion material from the North reduced so the formation of deltas slowed and eventually stopped. Rivers then started flowing into the area from the South and East, bringing large quantities of sand that were laid down across an area from Swansea to Oxford. </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">This is known as the Pennant sandstone which can be seen in the faces in Conyegar and Nowhere Quarries. The Pennant is up to 330m thick in the area and contains thin coal seams. There is also a good exposure of the Pennant at Trooper’s Hill in Bristol.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The direction of the rivers that supplied the material can be inferred from the channels and dune structures seen in the Pennant Quarry faces. This is called cross stratification.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">All the land masses then united to form the supercontinent Pangea.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">At the end of the Carboniferous period there are no rocks to be seen in the area from the following period, which is the Permian. ( 300 – 250 mya ) This could either be because the conditions were not right for any deposition to take place or they were deposited and have since been eroded away.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The next geological period is the Triassic. ( 250 – 200 mya ) The mountains that were created during the Variscan Orogeny are being rapidly eroded during this time. </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The coarse-grained products of this erosion are known as Dolomitic Conglomerate which can be seen as a skirt surrounding Broadfield Down. They create an unconformity with the Clifton Down Limestone that can be seen in, for example, the path bed running down from the Jubilee stone to Church Town. It can also be seen in the old quarry face in the disused Cheston Combe quarry. This unconformity can also be seen in many areas around the area, in the Tyntesfield quarries for example. This conglomerate has been used as a building stone in the area. It is probably best seen in the walls of the Tyntesfield sawmill. A similar rock, from Draycot Quarry on the South slope of the Mendips was famously specified by Brunel for building Temple Meads railway station.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The fine grained deposits are called Mercia Mudstone and can be seen surrounding the area as they merge into the dolomitic conglomerate.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">No rocks from the following periods, Jurassic ( 200 – 150 mya ) and Cretaceous ( 150 – 66mya ), remain in the area so, again, either they were deposited then eroded away or they were not deposited in the first place. </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Recent Quaternary ( 2.6 mya – present ) Drift material covers the low lying areas surrounding Failand Ridge, such as Nailsea Moor to the South and the Gordano Valley to the North. This is mainly Peat and Alluvium – clay, silt and gravel.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">This means that Broadfield Down is an eroded Carboniferous dome structure in a Triassic landscape. It is remarkable how much complex and interesting geology exists in such a small area.</span></span></div>
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<span style="font-kerning: none;"><b><span style="font-family: "arial" , "helvetica" , sans-serif;">A history of Badgers Wood Geology Trail - from the BET web site</span></b></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">After much discussion by the trustees about the possibility of a high-level cliff path in Badgers Wood, the project was given the go-ahead in the spring of 2013 and was finally completed in October 2014.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">In total, the new trail is around 350 metres long and runs along the base of some of the fantastic limestone cliffs to be found in this part of the woodland. The first and last sections have been relatively straightforward, but it was the bit in the middle, close to the cliff faces, that have required the full engineering skills of the trusty BET volunteers. </span></span><br />
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">We decided to start the trail in the middle, so if we ever felt we couldn’t overcome some of the more challenging technical problems, we could always simply walk away and no one would be the wiser!</span></span><br />
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The problem was that some sections of the trail had to be constructed on a very rocky, steep slope so the only real solution for us was to attach metal cages to the rock faces, fill them up with many tonnes of rock and then put the trail on top. Although this took a long time to do, I’m very pleased with the finished result as it’s now quite difficult to see the sections of trail that would once have been in thin air just a couple of years ago. </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The Geology Trail branches off the Fern Way close to the start/end of that trail.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">One word of warning though.... the trail does have some short, steep sections and you may need a head for heights on the more ‘challenging’ middle section!</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The route of the trail is shown on the updated <a href="http://www.backwellenvironmenttrust.org/index.php/bet-bulletins/maps/44-bet-map?task=weblink.go"><span style="-webkit-font-kerning: none; line-height: normal;">BET Map</span></a>.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">A slideshow of photos taken during the formal opening of the trail can be found here:-</span></span></div>
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<span style="font-kerning: none; text-decoration: underline;"><a href="http://www.backwellenvironmenttrust.org/index.php/2014-04-11-20-09-52/past-events/82-opening2014"><span style="font-family: "arial" , "helvetica" , sans-serif;">http://www.backwellenvironmenttrust.org/index.php/2014-04-11-20-09-52/past-events/82-opening2014<span style="-webkit-font-kerning: none;"></span></span></a></span></div>
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<span style="font-kerning: none;"><b><span style="font-family: "arial" , "helvetica" , sans-serif;">Description of Clifton Down Limestone.</span></b></span></div>
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<span style="font-kerning: none;"><b><span style="font-family: "arial" , "helvetica" , sans-serif;">Lithology.</span></b></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The lithology is dominated by calcite mudstones with a locally abundant but low diversity fossil assemblage. At Burrington Combe the formation is about 170 m thick, and three subdivisions can generally be recognised across the Mendip area. The lowest unit comprises a mixture of calcite mudstones, white oolitic limestones and dark splintery limestones. This interval is relatively expanded in the Cheddar area, where a 38 m thick dark limestone ('Cheddar Limestone Member') is overlain by a 58 m thick white oolitic limestone ('Cheddar Oolite Member'). The middle part of the succession is dominated by fine-grained, grey-black limestone with nodules and bands of chert and abundant remains of the coral <i>Siphonodendron</i>['<i>Lithostrotion</i>'] <i>martini</i> ('Lithostrotion Limestone'). Porcellaneous calcitic mudstones dominate the highest part of the formation, including locally developed algal mudstones and stromatolites, indicating deposition in a very shallow-water, near-shore or lagoonal environment.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Splintery dark grey calcite and dolomite mudstones, pale grey oolitic, dark grey bioclastic and oncolitic limestones and some mudstones. Scattered cherts and silicified fossils in lower half. Sandy limestone at base in Bristol area. Deposited in a barrier/back barrier/shelf lagoon setting.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Age range: Arundian Substage ( CJ ) - Holkerian Substage (CQ ) Early Carboniferous.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Thickness: Up to 266m in the Avon Gorge, thinning Southwards to 150 - 200m in the Mendip Hills.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Parent Unit: Pembroke Limestone Group</span></span></div>
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<span style="font-kerning: none;"><b><span style="font-family: "arial" , "helvetica" , sans-serif;">References</span></b></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">The BGS Lexicon of Named Rock Units<span class="Apple-tab-span" style="white-space: pre;"> </span>BGS</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">England and Wales sheet 264, Bristol Geological map<span class="Apple-tab-span" style="white-space: pre;"> </span>BGS</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">British Regional Geology memoir, Bristol and Gloucester<span class="Apple-tab-span" style="white-space: pre;"> </span>BGS</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Backwell Environmental Trust web site<span class="Apple-tab-span" style="white-space: pre;"> </span>BET<span class="Apple-tab-span" style="white-space: pre;"> </span></span></span><br />
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="http://backwellenvironmenttrust.org/index.php/bet-bulletins/maps" style="font-family: Calibri; font-size: 16px; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-ligatures: normal; font-variant-numeric: normal; font-variant-position: normal; line-height: normal; text-align: start;" title="http://backwellenvironmenttrust.org/index.php/bet-bulletins/maps">http://backwellenvironmenttrust.org/</a></span></span><br />
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<span style="font-kerning: none;">Grateful thanks to the BET Trustees for their permission to reproduce items here from their web site.</span></div>
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-90590720746018611572016-05-15T02:28:00.000-07:002016-05-15T02:30:04.955-07:00Saltford RIGS and Geology Trail<div style="-webkit-text-stroke-color: rgb(0, 0, 0); -webkit-text-stroke-width: initial; line-height: normal; margin-bottom: 8px;">
<span style="-webkit-font-kerning: none;"><b><span style="font-family: "arial" , "helvetica" , sans-serif;">Saltford RIGS and Geology Trail : – Exposures Exposing Work Continues in 2016 </span></b></span></div>
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<span style="font-kerning: none;"><i><span style="font-family: "arial" , "helvetica" , sans-serif;">Progress Report -- & Advertising of the Exposing Work to Continue to its ‘Cotham Marble Conclusion’, and the further great enjoyable opportunity to be a part of the work: later in the year …. Watch this space! …..As we local keen geo folk : Dig for Marble ! </span></i></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">About a month back, - earliest Spring (just about!?) -, a very good and keen team spirited group of a few (human! , not JCB) diggers, joined, over a few nourishing and warming flasks of sustenance, and dug happily for several hours, from a nice relaxed 10.30 or 11 am start.</span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Good progress has now been made, over two work days, to provide a great example exposure to tell the story of Saltford Geology, in a Trail, to be set up by local man, and well known palaeo man, Simon Carpenter, as shown in the photos here. In good relaxed friendly geology keenness fashion all 5 or 6 on the team on the 2nd work day, some weeks back now, near the Bristol to Bath cycle path, gathered and dug. …..Keen to unearth more of the wonders of the special and definitely Regionally Important geology found in Saltford. </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">For more detail on the special geology of Saltford there are leads on our Avon RIGS pages & also here linked below, for e.g., you could read up within : </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">http://earthwise.bgs.ac.uk/index.php/Geology_of_the_Bath_area:_Introduction </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">http://earthwise.bgs.ac.uk/index.php/Geology_of_the_Bath_area:_Jurassic </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">https://en.wikipedia.org/wiki/Cotham_Marble </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">And page 270 in this reference, on Late Triassic – Early Jurassic strata, for more on the Cotham Marble and other strata of the area: </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">https://www.earth.ox.ac.uk/~stephess/Hesselboetal2004.pdf </span></span></div>
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<span style="font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Simon (Carpenter) leading the way from the top of the embankment, which lies to the north of the former railway cutting, digging downwards through the strata, exposing a very good section,… towards the Cotham Marble bed….. To be hit very soon now, we hope…next Work Day! </span></span></div>
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<span style="-webkit-font-kerning: none;"><span style="font-family: "arial" , "helvetica" , sans-serif;">-Do join us. The more the keen hands the better.</span></span></div>
Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-78096693377216215882016-02-19T09:12:00.003-08:002016-02-19T09:37:17.263-08:00Aust Pylon and Talus Works<div style="-webkit-text-stroke-color: rgb(0, 0, 0); -webkit-text-stroke-width: initial; font-family: Arial; font-size: 14px; line-height: normal; text-align: justify;">
With the pylon at Aust coming up close to its 50<span style="line-height: normal;"><sup>th</sup></span> anniversary it is time that National Grid and Trant Engineering Limited give the concrete pillars it is stood upon some major renovation. As part of these works, that will continue throughout 2016, the concrete causeway that leads from the old ferry crossing down to the pylon will be in constant use. </div>
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Over many years soil and clay have accumulated at the base of the adjacent cliffs forming a huge bank pushing against the causeway. It was time for the bank to be removed. </div>
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During the first two weeks of February I was on site with a watching brief both for water birds using the foreshore and for fossils as the bank (talus) was removed and laid out across the beach. Two dumper trucks and two diggers were involved in transporting the soil and clay down to the beach. It was laid in two long rows along the beach enabling me to look through it. </div>
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Although there was some rock amongst the talus it was mainly slabs of shelly limestone rock that revealed some lovely bivalve fossils but nothing more. However, time on the beach did give me the chance to find plenty of Rhaetic bonerock – mostly containing the usual mix of tiny teeth, coprolites and fish scales. A few boulders revealed larger bone and shark spines. </div>
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I will be transferring the finds to Bristol Museum & Art Gallery – hand size pieces will be used as handling objects for learning activities. The bank itself has been cut back three metres and to a 45 degree angle. This will help reduce the pressure of future soil and clay building up against the road. The recent high tides have been washing through the talus and cleaning up any remaining slabs of limestone. </div>
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Ed Drewitt. Thanks also to Joe Keating and Dave Marshall from the School of Earth Sciences, University of Bristol, who covered a day each.<br />
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Talus being cleared at Aust<br />
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Fossil shells at Aust<br />
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Bonerock at Aust<br />
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Shark spine at Aust<br />
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Fossilised bone at Aust<br />
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-41040294545458966602016-02-03T06:24:00.005-08:002016-02-03T06:27:07.229-08:00Student reports new finds of a living fossil<div style="-webkit-text-stroke-color: rgb(176, 28, 46); -webkit-text-stroke-width: initial; color: #b01c2e; font-family: Arial; font-size: 23px; line-height: normal;">
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The coelacanth fish, found today in the Indian Ocean, is often called a ‘living fossil’ because its last ancestors existed about 70 million years ago and it has survived into the present – but without leaving any fossil remains younger than that time. Now, some much older coelacanth remains have been uncovered in a fossil deposit near Bristol by a student at the University of Bristol. </div>
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<span class="Apple-tab-span" style="white-space: pre;"> </span><span style="font-size: 14px; line-height: normal;">The Jurassic coelacanth Undina, similar to the new finds from near Bristol.<span class="Apple-tab-span" style="white-space: pre;"> </span></span><span class="Apple-tab-span" style="white-space: pre;"> </span><i>Image credit<span class="Apple-tab-span" style="white-space: pre;"> </span>Harry Allard</i></div>
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While working last summer in Bristol’s <a href="http://www.bristol.ac.uk/earthsciences/"><span style="color: #0f7ca4; line-height: normal;">School of Earth Sciences</span></a>, Harry Allard, a recent graduate from the University of Exeter, found remains of coelacanth fishes, ranging in size from juveniles to adults, in a section of Late Triassic rocks, dated at about 210 million years old, at Manor Farm, Aust, close to the first Severn crossing.<br />
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He discovered the new fossils in a large collection of fish and reptile teeth and bones, representing animals that lived in the shallow seas, and on the neighbouring landmass at that time when Bristol teemed with dinosaurs, and the landscape consisted of numerous tropical islands.</div>
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Harry said: “These fossils provide an amazing glimpse of an ecosystem which is so different from the contemporary landscape of south west England. It has been fascinating to look at the changing composition of that long-lost ecosystem.”</div>
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The Manor Farm site was created 15 years ago when the second Severn crossing was under construction and contractors excavated there to obtain road-building materials. After the site was made safe, a section was dug out so geologists, and the public, could visit and learn about the local geology. One of the fossil collectors at the time, the late Mike Curtis of Gloucester, collected batches of sediment, and worked through the material to extract nearly 20,000 teeth and bones.<br />
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“Mike Curtis kept such excellent records that Harry was able to separate the collections into findings from five separate bone beds, each perhaps separated by a few hundred thousand years,” said <a href="http://www.bristol.ac.uk/earthsciences/people/mike-j-benton/"><span style="color: #0f7ca4; line-height: normal;">Professor Michael Benton</span></a>, supervisor of the project. “This provides unique insight into a turbulent time, when seas flooded across the landscape, submerging much of Europe. Dry land became shallow seas almost overnight, and the energy of the floods churned up the soil and rock below and deposited bone beds in some places.”<br />
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Tracking upwards through the five bone beds, Harry was able to show how the fish faunas changed through time, from being dominated by small sharks at first, and then switching to more thick-scaled bony fishes higher up.<br />
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“The coelacanths were smaller than the living coelacanth <i>Latimeria</i>,” said Chris Duffin, a fossil fish expert who was involved in the work, “but these fishes were quite diverse in the Triassic, and only dwindled in importance later. They are most unusual, having gills and lungs, and moving both by paddling with their gills, and stilt-walking along the seabed as well.</div>
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<b>Paper</b></div>
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‘Microvertebrates from the classic Rhaetian bone beds of Manor Farm Quarry, near Aust (Bristol, UK)’ by Harry Allard, Simon Carpenter, Chris Duffin, and Michael Benton in Proceedings of the Geologists’ Association(doi: 10.1016/j.pgeola.2015.09.002)</div>
Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-1120037358955880712015-10-18T02:02:00.002-07:002015-10-19T02:21:18.478-07:00Rock clearance day at Salford<div style="font-family: Helvetica; font-size: 12px; line-height: normal;">
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<b>Rock clearance day at Saltford</b><o:p></o:p></div>
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<b>Friday 20 November </b><o:p></o:p></div>
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<b>Meet: 10:30am</b> at the clearance site. Finish at 4pm.<o:p></o:p></div>
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Dear volunteers<o:p></o:p></div>
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<b>I am organising a rock clearance day on Friday 20 November to clean up a late Triassic/White Lias site close to the Railway Path at Saltford ST 691668 (see attached map). The site will eventually be part of a new geology trail around the village and I need your help</b><o:p></o:p></div>
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The rock outcrop occurs along the rim of the cutting and I need a team to help clear ivy and vegetation covering the current rock face as well as removing a substantial talus slope that covers and obscures the lower part of the exposure. It should be possible to complete this work in one day.<o:p></o:p></div>
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If you are interested (volunteer days can be real fun, especially if the weathers nice), please ring or email me to register your interest: 01373 474086 and/or <a href="mailto:simonccarpenter@gmail.com" style="color: purple;">simonccarpenter@gmail.com</a><o:p></o:p></div>
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You will need to bring a spade, thick work gloves, secateurs and or loppers - some extra tools will be available if you don't have any of your own. Bring packed lunch or there is the Bird in Hand pub a short distance away. Bring lots to drink and warm clothing, if its cold. <o:p></o:p></div>
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There is a regular bus service to Saltford (X39) from Bath and Bristol or the site can be reached by bicycle of walking. There is some car parking near the River Avon at 'The Shallows' and the rock exposure can be reached from here by a short walk. There will be signs placed on the railway path adjacent to the rock exposure so that you don't miss it. <o:p></o:p></div>
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With best wishes Simon Carpenter<br />
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com1tag:blogger.com,1999:blog-3978721426489298938.post-79190669066716714622015-01-15T02:45:00.002-08:002015-05-11T01:00:29.625-07:00The Geology of Clifton and Durdham Downs<div style="font-family: Helvetica; font-size: 12px; margin-bottom: 0cm;">
<strong>The Geology of Clifton and Durdham Downs by Andrew Mathieson</strong><br />
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<i>Reproduced from Nature in Avon, volume 73 (2013), with the permission of the Bristol Naturalists' Society.</i></div>
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Little has been written about the geology of the Downs, in contrast to the many accounts of that of the Avon Gorge. This is hardly surprising since the Gorge is nationally important for both the exposed rock sequence and the landform itself, but the Downs do have a number of different and special geological features. The two sites are very closely linked since most of the rocks seen in the Gorge also lie under the Downs, but there are several younger rocks on the Downs which are not found in the Gorge, and these add greatly to our understanding of the geological history of the area. </div>
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<strong>The Rock Succession</strong></div>
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The oldest group of rocks on the Downs is the Carboniferous Limestone, and this underlies most of the area. It is a thick sequence of some 760 m (2,500 ft) of rock, and is mostly made up of different types of limestone, but there are also dolomites, mudstones and sandstones. These all contain the fossil brachiopod shellfish, corals and crinoids, clearly indicating that the rocks formed beneath the sea. The presence of corals and limestone suggests that the water was shallow and warm, and this is supported by studies of palaeomagnetism, which indicate that these rocks formed close to the equator. Radiometric evidence shows that they are between 359 and 343 million years old.</div>
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The sequence of Carboniferous Limestone is divided into a series of units, which are mostly named after exposures seen along the Gorge (Kellaway and Welch, 1955). These units were created by the Geological Survey to replace a system of zones based on fossil corals and brachiopds (Vaughan, 1905) which, although revolutionary at the time, had been found to be difficult to use outside the Bristol area. The new system is based on units of types of rock which can be traced across the area from the Mendips to South Gloucestershire. The Gorge is famous as the reference site for both of these methods of dividing the limestone succession (Bradshaw and Frey, 1987; Hawkins, 1987).</div>
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The main Geological Survey units present on the Downs are:</div>
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<strong>Black Rock Limestone</strong> is the oldest unit, and it can be traced in a band across the north of the Downs from Sea Walls to Badminton School, and forms the northern edge of the high ground. It takes its name from Black Rock Quarry in the Gorge, where it is well exposed, and is a dark grey, well bedded limestone with many fossil crinoids, corals and brachiopods.</div>
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<strong>Gully Oolite</strong> outcrops across the Downs to the south and parallel to the Black Rock Limestone from near the top of the Gully. It is a light grey coloured oolitic limestone, with few fossils and little evidence of bedding. The rock is best seen in the Gully Quarry in the Gorge. Modern day oolite sediments are found in shallow seas subject to bottom currents.</div>
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<strong>Clifton Down Mudstone</strong> is a relatively softer rock and its course across the Downs runs parallel to the other older rocks, starting from where it was eroded out to form the top of the Gully. The rock is poorly exposed in the Gorge but its base can be seen at the top of the Gully Quarry. The contact with the Gully Oolite beneath is irregular, suggesting that erosion took place at that time and the junction between the units is interpreted as a fossil soil. The presence of mudstones indicates that mud was washed into the sea by rivers from nearby land, but there are also beds of limestone which show that the seawater cleared at times.</div>
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<strong>Clifton Down Limestone</strong> is found both on Durdham and Clifton Downs, since it was displaced by large scale faulting. It is rich in fossils and is sometimes oolitic. There are also some fossil algal structures which suggests an inter-tidal origin for some of the rock.</div>
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<strong>Hotwells Limestone</strong> is again found on both Durdham Down and on the south side of Clifton Down due to the action of the same faulting. It is a well bedded limestone, rich in fossil corals and shellfish, and is best exposed around the foot of the Old Zigzag and the entrance to the former Clifton Rocks Railway. The Upper Cromhall Sandstone, at the top of this unit, is not actually present on the Downs, but is well exposed at the bottom of Bridge Valley Road, and mainly consists of red sandstones and mudstones.</div>
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All these rocks in the Gorge and on the Downs were subjected to enormous forces during a major period of earth movements around the end of the Carboniferous period, about 300 million years ago. They were compressed and became part of a massive arched fold (the Westbury-on-Trym Anticline), which extended from Clifton northwards to Kingsweston and Henbury. In addition a number of faults were formed and the largest of these, the Great Fault, can be seen at the bottom of Bridge Valley Road. Here Clifton Down Limestone is pushed up over Cromhall Sandstone with the result that the upper part of the rock sequence in the Gorge (and on the Downs) is repeated to the south. The movement of this major fault is calculated as 335 m (1,100 ft), and it has had the effect of extending the length of the Downs (and the Gorge) by about a third. These earth movements also created sets of joints in the rocks and some of these have since been filled with younger rocks or mineral veins.</div>
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The fold must have also included a thick sequence of younger Carboniferous rocks which once covered the Limestone on the Downs. These Coal Measure rocks are found beneath Ashton Vale, where coal seams are found in mudstones and sandstones, and must have been deposited in the equivalent of the tropical rain forest of 315 million years ago. The local Coal Measures are some 600 m (2,000 ft) thick, but much more was probably once present and when they lay on top of the Limestone in the fold, the Downs area must have been on the southern slope of a mountain which could have been over 3,000 m (10,000 ft) high at Westbury on Trym. There followed nearly 100 million years of erosion which almost completely removed the mountain, basically leaving the Downs and Kingsweston Hill as the highest remaining stumps.</div>
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Much of the south of the Downs is covered by Dolomitic Conglomerate, a rock composed of pebbles and boulders of limestone in a matrix of sandstone and mudstone. This was created from the eroded remains of the Carboniferous Limestone. The best exposure of this rock is in a cutting on Bridge Valley Road, where it can be seen to lie in horizontal layers. This appears to represent the infill of a fossil valley cut into the relatively softer Cromhall Sandstone. The rock was formed between 250 and 200 million years ago, in the Triassic period of geological time, when the Downs are thought to have been an area of high ground in an arid desert. </div>
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There are some areas of younger Triassic rocks on the Downs. Westbury Beds are found around Clay Pit Road, where they were quarried in the 1780's (Savage, 1999), and also near the centre of Durdham Down. These black coloured mudstones contains fossils which indicate a marine origin, and provide evidence that at least some of the eroded surface of the desert landscape was covered by the sea about 200 million years ago.</div>
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<strong>The Downs Island</strong></div>
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The fossil remains of the “Bristol Dinosaur” <em><u>Thecodontosaurus antiquus </u></em>were found in a fissure in a limestone quarry on the edge of the Downs, near the top of Blackboy Hill, in 1834. A quarryman took one or two fragments of fossil bone to the Bristol Institution (which later became Bristol City Museum) where they were examined by the curator and by a number of experts. Men were employed to find more fossils and a large collection was made. This dinosaur was only the fourth named in England, and perhaps the world (Benton, 2012). Sadly some of the fossils were destroyed by bomb damage in the Second World War but 184 specimens are still safely stored in the Geology Department of the City Museum and Art Gallery. It was generally thought that the bones were preserved in Dolomitic Conglomerate which had formed in the fissure, but recent research has found evidence that the fissure fill is equivalent in age to the Westbury Beds. This is based on the presence of some fossil shark teeth and the similarity of many of the fossils to those found in South Gloucestershire where evidence of Westbury BedsS was established. The same research revealed fossil evidence for a number of other dinosaurs and terrestrial reptiles which must have lived alongside <em><u>Thecodontosaurus</u></em> on the Downs Island of the time (Foffa, 2014).</div>
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Near the Bristol entrance to the Suspension Bridge there is a small deposit of more Triassic, and possibly also Jurassic rock, which appears to have been deposited in a cave or fissure in the Carboniferous Limestone. Tawney (1875, p. 164) described this deposit as: </div>
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<em>a wide fissure (or pocket) in which blocks of Cotham-marble are found imbedded. Lias Septaria too were dug out of it in making the road to the bridge and the excavations for the bridge chains. The bulk of the infilling material seems to be greenish marl, with a little red marl such as occurs in the Rhaetics.</em></div>
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Cotham Marble is found in the Cotham Beds, which are of Triassic age, and younger than the Westbury Beds. The Marble is a well known local limestone formed by fossil algae, suggesting inter-tidal conditions. The Cotham Beds have not been recorded elsewhere on the Downs. The Lias mentioned by Tawney is the lowest division of the local Jurassic rocks. These occurences imply that the site was on the shoreline of an island, sited where the Downs are today, which existed from the time when the Cotham Beds were deposited through to the early Jurassic period. </div>
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Charles Moore (1881) later wrote about the same site:</div>
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<em>Close to the toll house, on the Clifton side, there is a deposit of considerable interest, having a face of about forty feet, in which the Rhaetic bone-bed and its asscociated remains are present. It is partly composed of irony and yellow sandy looking marl, with many free crystals of carbonate of lime .. and there are patches of finely lamintated rock, similar to the Rhaetic “White Lias”.... The bone-bed is two inches thick, with teeth of <u>Saurichthys apicalis</u>, <u>Lophodus minimus</u>, and many fish scales, and the clay on either side contains fish-remains of the same age.</em></div>
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The Bone Bed with its various fossil fish remains is found in the Westbury Beds, which suggests that the coast existed from before the Cotham Beds were formed. </div>
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It is thought that the Island was completely drowned by the sea later in the Jurassic period, since pieces of Lias limestone with fossil <em><u>Gryphaea</u></em> and <em><u>Spiriferina</u></em> have been found on the Downs (Donovan and Kellaway, 1984, p. 20). These are presumably derived from Jurassic deposits hidden beneath the soil.</div>
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<strong>Durdham Down Bone Cave</strong></div>
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The youngest deposits on the Downs were found in the famous Durdham Down Bone Cave. According to Latimer (1887, pp 265-266):</div>
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<em>An interesting geological discovery was made in November 1842, in one of the quarries which then worked in the middle of Durdham Down, the workmen having found an opening into a cavern containing a quantity of the remains of animals for ages extinct in this country. The cavity though narrow, was of some extent, being traceable to a depth of ninety feet. The bones had belonged to about twelve hyenas, a bear, two rhinoceros, several hippopotami, numerous examples of wild bulls, about five deer, and five or six elephants, besides the relics of animals of later date. The bones were nearly all fractured into small pieces, and the proportion of teeth and horns to other parts of the body greatly preponderated. Taking this fact into consideration, together with the marks of gnawing on the bones, and the certainty that the cave could not have accommodated more than a small fraction of the animals represented by the vestiges, scientific observers concluded that the den had been the retreat of hyenas, which had carried to it portions of their prey.</em></div>
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The fauna mainly represents animals which lived in the last warm phase of the Ice Ages (Ipswichian interglacial, between 128,000 and 116,000 years ago). Much of the material was acquired by the Bristol Institution, which later became Bristol Museum, and some was lost in the Blitz of 1940. <span style="font-family: 'Times New Roman', serif;">D</span><span style="font-family: 'Times New Roman', serif;">espite reports that this entire collection had been lost from the Museum as a result of the event, on the contrary, there is a significant collection present today, including:</span></div>
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Spotted Hyaena <em><u>Crocuta crocuta</u></em> <span style="font-family: 'Times New Roman', serif;">(including a specimen on display)</span></div>
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<span style="font-family: 'Times New Roman', serif;">Cave Bear <em></em><em><u>Ursus spelaeus</u></em><em></em></span></div>
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<span style="font-family: 'Times New Roman', serif;">Brown Bear <em><u>Ursus arctos</u></em></span></div>
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<span style="font-family: 'Times New Roman', serif;">Small-nosed Rhinoceros <em><u>Rhinoceros leptorhinus</u></em></span></div>
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<span style="font-family: 'Times New Roman', serif;">Hippopotamus <em></em><em><u>Hippopotamus amphibius</u></em><em></em></span></div>
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‘<span style="font-family: 'Times New Roman', serif;">Cattle’ or Bison<em> </em><em><u>Bos sp</u></em><em> </em>or<em><u> Bison sp</u></em><em></em></span></div>
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<span style="font-family: 'Times New Roman', serif;">Deer<em> </em><em><u>Cervus </u></em><em></em></span></div>
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<span style="font-family: 'Times New Roman', serif;">Straight-Tusked Elephant<em> </em><em><u>Palaeoloxodon antiquus </u></em>(including a specimen on display)<em></em></span></div>
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<span style="font-family: 'Times New Roman', serif;">Red Fox<em> </em><em><u>Vulpes vulpes</u></em><em></em></span></div>
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A model of the cave is also preserved in the Geology Department of the City Museum and Art Gallery.</div>
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<strong>Natural Landscape</strong></div>
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The Downs plateau is a remarkable feature which extends across the area at a hieght of around 100m (330 ft) above sea level, and can be seen to continue across the other side of the Gorge. Most geologists have concluded that it is an ancient surface formed following the very long period of erosion after the late Carboniferous earth movements. They consider that it was planed off at the end of the Triassic and beginning of the Jurassic periods, as the sea advanced across the area. There is certainly evidence for marine sediments of this age on and around the edge of the Downs. The area is then thought to have been covered with a very thick sequence of younger Jurassic and possibly Cretaceous rocks, which would have completely buried the erosion surface. These would have been affected by earth movements in the Tertiary period, with the result that they dip at a low angle towards the south east. Subsequent erosion has removed most of these rocks and exhumed the buried Triassic landscape. </div>
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It is likely that this long period of erosion had some effect on the Downs plateau, and also possible that the postulated presence of an ice sheet during the Ice Ages made further changes. The erosion of the Gully and the New Zigzag valleys must have taken place when the Gorge was created. Given that these are now dry valleys, and that any rainwater that falls on the Downs sinks down through the limestone, it probably required the ground to be frozen to allow water to run across the land surface to erode the features. This could have happened during any of the cold phases of the Ice Ages, but the present shape of the valleys was no doubt completed in the last, the Devensian, between 116,000 and 11,000 years ago. </div>
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There are a number of caves in the area but most are found in the sides of the Gorge. However, the Observatory Hill Cave entrance is on Clifton Down, to the east of Observatory Hill. Its entrance has been blocked up, but it was reported to be 9 m (30 ft) long, 1.5 m (5 ft) high and 3 m (10 ft) wide. There is no known evidence of when it was formed. The Durdham Down Bone Cave was discovered in a quarry but must have once had an entrance on the Downs. There may well be more undiscovered caves and solution cavities on the Downs which were formed as rainwater found its way down through joints and other openings in the limestone. There are several small depressions on the Downs which could be sink holes, but which may turn out to be unrecorded mineral workings. One pit is thought to be a Second World War bomb crater.</div>
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It has been suggested that much of the surface of the Downs was formerly covered by limestone boulders and griked bedrock, and that this was mostly removed by lime burners or as ornamental stone for use in rockeries (Kellaway and Welch, 1993, p. 48). Clearly the natural landscape has been considerably altered by quarrying and mining. </div>
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<strong>Quarrying</strong></div>
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<span style="font-family: arial, helvetica, sans-serif;"><span style="font-size: x-small;">Quarry thought to be to the west of the junction of Ladies Mile and Stoke Road</span></span></div>
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<span style="font-family: arial, helvetica, sans-serif;"><span style="font-size: x-small;">Watercolour by William Arnee Frank, c.1862 </span></span></div>
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<span style="font-family: arial, helvetica, sans-serif;"><span style="font-size: x-small;">©Bristol Museums, Galleries and Archives</span></span></div>
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There have been many quarries which extracted Carboniferous Limestone on the Downs (see the map in Greenacre, The Downs History Trails No. 1). In 1754 it was reported that locals were permitted to take what stone they required from the Downs, and that much was burnt in kilns to make lime for mortar (Savage, 1999). Some was also used as building stone, with the Observatory, for example, almost entirely built of this rock. The only two quarries which have survived are around Observatory Hill. </div>
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In addition to the many small quarries there were four much larger:</div>
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Quarry north of Westbury Road and marked by the Seven Sisters pine trees</div>
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Quarry to the north west of the junction of Stoke Road and Ladies Mile</div>
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Chain Quarry, north of Belgrave Road</div>
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Pembroke Road Quarry, north of Clifton Down</div>
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Quarry 1 was reported as being nearly 1.2 hectares (3 acres) in area with an average depth of 9 m (30 ft). Quarry 2 is thought to be the site of the Durdham Down Bone Cave, and had an area of nearly 1.6 hectares (4 acres) and also an average depth of 9 m (30 ft). This appears to be the quarry depicted in a watercolour by William Arnee Frank (1862), and, if so, seems to have been much deeper in part. The Clifton and Durdham Downs (Bristol) Act of 1861 established a number of duties, including the closure and infilling of existing quarries. One of the Downs Committee's first actions was to give notice to all quarry users to quit by October 1862. In 1866 the Docks Engineer proposed to the Downs Committee that these now disused quarries should be infilled with the material to be excavated when straightening the course of the River Avon and constructing a new lock at the entrance to Cumberland Basin. This was agreed and the Dock Spoil Tramway was built to carry the excavated material up onto the Downs.</div>
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By October 1871 Quarries 1 and 2 were filled and landfill began at the Chain Quarry. The clump of pines known as the Seven Sisters was planted at the site of Quarry 1 in 1872, and the tramway track was removed in 1873, after the completion of the new Cumberland Basin lock. Chain Quarry was finally filled by 1879. In 1890 Pembroke Road Quarry was identified as a landfill site for the material to be excavated during the construction of the Frome Culvert and this was completed in about 1907 (Nichols, 2005). The boundaries of some of these former quarries can be traced due to some settlement of the infill, and no doubt 9 m of river sediment and assorted rocks will have had a significant effect on the type of soil which has developed on these sites.</div>
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<strong>Minerals and Mining</strong></div>
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There is an area of disturbed ground known as the Dumps beween Upper Belgrave Road and Ladies Mile. This is unlike any other feature on the Downs and its origin is unknown. It has been suggested that it was a former lead mining area, but the alignment of the workings are quite different from that of the known lead veins nearby. It has also been suggested that it was a former limestone quarry but it does not have the appearance of any other quarry on the Downs. Other suggestions are that the mineral celestite was worked here, or that the trenches were lead workings which were later enlarged by quarrying to supply limestone (Kellaway and Welch 1993, p. 50).</div>
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Several minerals have been found on the Downs. Galena was worked as lead ore, and several veins run north westwards from opposite the Zoo. The remains of some of the “grooves” dug by lead miners as they followed the lines of the mineral veins are still visible.The mineral has been recorded at several other sites on the Downs, including in old workings north and south of the White Tree, in the highly mineralised belt at the northern end of Durdham Down (Kellaway and Welch, 1993). The Romans are commonly thought to have worked lead and there is a reference that the mineral was dug on the Downs in the Anglo-Saxon Charter of 883. The first clearly documented record is for 1611 when the Lord of the Manor of Henbury granted a licence to dig for lead on Durdham Down. In 1712 another lease was granted to mine lead ore as well as iron, manganese and calamine on the Downs (Micklewright and Frost, 1988).</div>
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Iron ore was extracted in Clifton, but there is no definite evidence that it was worked on the Downs. In 1872 an iron mine was opened below Royal York Crescent in Clifton and it produced 3,000 tonnes (3,800 tons) of ore in that year. Two beds of hematite, goethite and limonite were worked in red sandstone and shale (Savage, 1999). </div>
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The mineral Calamine (now called Smithsonite) was said to be the <em>“most important mineral in point of frequency and value that the limestone yields. “</em> (Bright, 1817, p.200). It was a valuable source of zinc which was amalgamated with copper to form brass in local mills. The mineral was found in veins cutting the limestone, together with calcite, barite and galena. Bright records that: <em>“The calamine has hitherto been worked in a very imperfect manner: the vein is broken into, when it meets the surface; a rough windlass is placed over the hole, and a bucket is attached to a few fathoms of rope; two or three men work at the vein as long as the ore is found in abundance, or until the water impedes their progress. The mine is then deserted, but the heaps of rubbish at the mouth of the pit are often so rich in ore that considerable sums are paid for the privilege of washing them.”</em></div>
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Quartz geodes were once extracted from the rocks around Observatory Hill and sold to visitors as “Bristol Diamonds”. Also more prosaically known as Potato Stones, these nodules of quartz are thought to have replaced the mineral anhydrite. The most prized form was a hollow geode with quartz crystals growing in towards the centre. These were very popular with people who came to visit the Hotwells Spa, and could be purchased from shops in the Colonnade. References to Bristol Diamonds go back to 1540 when Camden wrote: <em>in hills about Bristow be found little stones of divers colours counterfeiting precious stones</em>. Probably the largest collection of Bristol Diamonds is in the grotto in the garden of Goldney House in Clifton, which was built in the 1740's. The geodes were found in both the Dolomitic Conglomerate and in iron ore veins cutting through the Carboniferous Limestone (Savage, 1999).</div>
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Lead veins found on Clifton Down beneath the Triassic Westbury Beds consist of galena, sphalerite and marcasite, with barite and calcite. Elsewhere the veins in the Carboniferous Limestone show two generations of mineralisation. The first consists of hematite and quartz, followed by galena, barite and calcite, which may be deposited in a central infilling of the vein (Kellaway and Welch, 1993, p. 143). </div>
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Celestite has been recorded found in the local Triassic rocks, but there is no evidence that it was worked on the Downs. However on the other side of the Gorge, in Abbots Leigh, there were extensive workings for the mineral in the late nineteenth and early twentieth centuries. These were considered to be among the richest worked in the Bristol district, with some boulder sized masses weighing up to half a ton (Kellaway and Welch, 1993, p.134).</div>
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<strong>Conclusion</strong></div>
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The 1861 Downs Act certainly preserved a green open space for the citizens of Bristol, but it also unfortunately led to the infilling of most of the quarries which once provided information about the geology of the area. Sadly the Bone Cave is completely buried but at least many of the fossils excavated from the site have survived in the City Museum and Art Gallery. The two remaining quarries on Observatory Hill very clearly display the dip of the rocks and this is much appreciated by the younger generation as a slide. The road cutting leading to the Suspension Bridge exposes a splendid array of fossils and mineral veins, as well as a rock which probably once filled a cave on the coast of the Downs Island of just over 200 million years ago. Hopefully these special places will be conserved for future generations to appreciate.</div>
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Andrew Mathieson</div>
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<strong>References</strong></div>
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Benton, M.J., 2012, Proceedings of the Geologists' Association, 123, pp. 766-778</div>
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Bradshaw, R. and Frey, A.E., 1987, Proceedings of the Bristol Naturalists' Society, 47, pp. 45-64</div>
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Bright, R., 1817, Transactions of the Geological Society, pp. 193-205</div>
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Donovan, D.T. and Kellaway, G.A., 1984, Geology of the Bristol District: the Lower Jurassic Rocks, British Geological Survey, 69 pp.</div>
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Foffa, D., 2014, Proceedings of the Geologists' Association. (<em>in press</em>)</div>
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Greenacre, F.,The Downs History Trails No. 1, Durdham Down</div>
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Hawkins, A.B., 1987, Proceedings of the Bristol Naturalists' Society, 47, pp. 65-78</div>
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Kellaway, G.A. and Welch F.B.A., 1955, The Bulletin of the Geological Survey of Great Britain, 9, pp. 1-21</div>
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Kellaway, G.A. and Welch F.B.A, 1993, The Geology of the Bristol District, British Geological Survey, 200 pp.</div>
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Latimer, J., 1887, The Annals of Bristol in the Nineteenth Century, W and F Morgan, Bristol, 552 pp.</div>
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Micklewright, S.D. and Frost, L.C., 1988, University of Bristol Avon Gorge Project Report No. 10</div>
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Moore, C. 1881, Quarterly Journal of the Geological Society of London, 37, pp. 67-82</div>
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Nichols, G., 2005, To Keep Open and Unenclosed: The Management of Durdham Down Since 1861, Bristol Branch of the Historical Association, Pamphlet No. 116, 40 pp. </div>
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<span style="font-family: arial, helvetica, sans-serif;">Savage, R.J.G.,1999, Proceedings of the Bristol Naturalists' Society, 59, pp. 65-76</span></div>
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<span style="font-family: arial, helvetica, sans-serif; font-size: x-small;">Tawney, E.B., 1875, Proceedings of the Bristol Naturalists' Society, pp. 162-166</span></div>
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<span style="font-family: arial, helvetica, sans-serif; font-size: x-small;">Vaughan, A., 1905, Quarterly Journal of the Geological Society of London, 61, pp. 181-307</span></div>
Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-40908732677158904202013-10-14T03:59:00.002-07:002013-10-14T04:03:14.956-07:00The Avon Gorge: Thrusting under our noses<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="font-family: Verdana,sans-serif;"><em><span style="font-size: x-small;">This post was originally featured on the University of Bristol Earth Sciences PhD blog "Between a rock and a hard place" <a href="http://betweenarock.co.uk/fieldwork/science-snap-7-thrusting-under-our-noses/">http://betweenarock.co.uk/fieldwork/science-snap-7-thrusting-under-our-noses/</a></span><a href="http://blogs.egu.eu/bar/?p=203" target="_blank"></a></em></span><br />
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</span><span style="font-family: Verdana,sans-serif;">As Earth Science researchers, we are extremely fortunate that fieldwork often necessitates trips to <a href="http://betweenarock.co.uk/where-in-the-world/" target="_blank" title="Where in the world?">exotic and far-flung places</a>. But sometimes we are guilty of ignoring the riches right on our doorstep.</span><br />
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</span><span style="font-family: Verdana,sans-serif;">In Bristol, perhaps our greatest geological asset is the <a href="http://en.wikipedia.org/wiki/Avon_Gorge" target="_blank">Avon Gorge</a>.
At the end of the Last Glacial Maximum, torrents of icy meltwater
scoured out a 2.5km long gouge through a series of Devonian and
Carboniferous limestones and sandstones. The bottom of the 90m deep
gorge is now filled with the River Avon and the sheer cliffs of the
north side are home to fossil corals, <a href="http://www.avongorge.org.uk/wildlife.php?ContentID=8" target="_blank">rare plants</a> and challenging <a href="http://www.ukclimbing.com/logbook/crag.php?id=31" target="_blank">climbing routes</a>; they also expose an excellent thrust fault.</span><br />
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</span><span style="font-family: Verdana,sans-serif;">This particular example lies at the intersection between Bridge
Valley Road and the Portway, just underneath the Clifton Suspension
Bridge (<a href="https://mapsengine.google.com/map/edit?mid=zmwwmvCNZz9U.kS04lPoj4cD8" target="_blank">see here for map</a>). Compressional forces associated with the formation of the supercontinent <a href="http://geology.com/pangea.htm" target="_blank">Pangea</a>
(~290 Ma) caused the the older Clifton Down Limestone to be thrust over
the younger Upper Cromhill Sandstone. Friction along the overhanging
fault plane deformed the younger sediments, and the resulting
instability of the rock face has caused <a href="http://www.bbc.co.uk/news/uk-england-bristol-12303255" target="_blank">major issues for the adjacent roads</a>.</span><br />
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<tr><td style="text-align: center;"><a href="http://betweenarock.co.uk/wp-content/uploads/2013/09/IMG_0399-1024x768.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://betweenarock.co.uk/wp-content/uploads/2013/09/IMG_0399-1024x768.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Verdana,sans-serif;"><b><span style="font-size: x-small;">Thrust fault in the north side of the Avon Gorge where the older grey
Clifton Down Limestone (right) has been thrust over the younger red
Upper Cromhall Sandstone (left); the intensity and friction of the
thrusting is manifest in the deformation of the younger sediments. The
fault outcrops at the intersection between Bridge Valley Road the
Portway (A4) and is conveniently located adjacent to set of traffic
lights and a cycle path – look out for it next time you’re stuck on a
red light or peddling past.</span></b></span></td></tr>
</tbody></table>
<span style="font-family: Verdana,sans-serif;"><span style="font-family: "Courier New",Courier,monospace;"><span style="font-size: xx-small;">Charly Stamper </span></span></span><br /><span style="font-family: Verdana,sans-serif;"></span><br />
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Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-7459453030776237732013-09-27T03:01:00.001-07:002013-09-27T03:04:17.660-07:00Free public lecture on Stromboli Volcano - 17th October 6pm<div dir="ltr" style="text-align: left;" trbidi="on">
<div>
<span style="font-family: Verdana,sans-serif;"><b>Thursday 17 October at 6 pm</b></span></div>
<span style="font-family: Verdana,sans-serif;">
</span>
<div>
<span style="font-family: Verdana,sans-serif;"><b>Reception Room, Wills Memorial Building, Queen's Road, BS8 1RJ</b></span></div>
<br />
<div style="text-align: center;">
<span style="font-family: Verdana,sans-serif;"><span style="color: blue;"><i>Free entry, booking not required</i></span></span></div>
<div style="text-align: center;">
<a href="http://bristol.ac.uk/pace/public-events/inaugural/2013/mader.html"><span style="font-family: Verdana,sans-serif;">http://bristol.ac.uk/pace/public-events/inaugural/2013/mader.html</span></a></div>
<div style="text-align: center;">
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<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXJjaulXPIyt3BmecZ7divBbQyAl4CpvpIjsj9lWZXRytL3PvfYX3i2hrIpioZxMMxzKQGid92iOZVHNGvK6khq7ZO3UX1l5Lw0XDyQWrGyMTXcGk4ljViaRj4nbuWdIxMOQ24FcXsybWY/s1600/Heidy+Mader+poster+copy.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXJjaulXPIyt3BmecZ7divBbQyAl4CpvpIjsj9lWZXRytL3PvfYX3i2hrIpioZxMMxzKQGid92iOZVHNGvK6khq7ZO3UX1l5Lw0XDyQWrGyMTXcGk4ljViaRj4nbuWdIxMOQ24FcXsybWY/s400/Heidy+Mader+poster+copy.jpg" width="282" /></a></div>
<div style="text-align: center;">
<br /></div>
<span style="font-family: Verdana,sans-serif;"><br /></span>
<span style="font-size: x-small;"><b><span style="font-family: Verdana,sans-serif;">ABSTRACT:</span></b></span><br />
<span style="font-family: Verdana,sans-serif;">Stromboli volcano (Italy) belongs to a class of volcanoes that explode
frequently against a background of substantial continuous gas emissions.
The explosions are spectacular and the continuous gas emissions have a
significant effect on the Earth’s atmosphere. This lecture will consider
the processes involved that allow these two modes of behaviour
(explosions and gas emissions) to co-exist. In particular, I will show
how we can combine results from laboratory flow experiments and computer
models with field observations and petrological and textural data from
rock samples to advance our understanding of this style of eruptive
behaviour.</span></div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-76899987608183231462013-07-10T13:52:00.000-07:002013-07-10T13:53:20.963-07:00The Bristol 'tsunami': Flood or fallacy?<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: center;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><span style="color: #134f5c;"><i><span style="font-size: x-small;">This post was originally featured on http://betweenarock.co.uk/</span></i></span><b> </b></span></span></div>
<br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><b>30<sup>th</sup> January 1607*</b>.</span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><i>The day
dawns sunny and bright. You are ploughing a field in your smallholding
deep in the Somerset Levels. As the sweat drips down your back, you hear
a distant rumbling sound but think nothing of it; the wind has been
blowing a gale all night. Suddenly, a shout from a neighbour makes you
look up in alarm. At the end of the far field you see a great cloud
hugging the ground, light dazzling off the whiteness. At first you are
confused: is it fog, or smoke from a fire? But then you realise, it's
water. Within ten seconds, the tumbling, roaring mass has advanced the
length of the paddock. You try to run but it's too late. Knocked off
your feet by the force of the wave, your head dips below the surface and
you inhale a lungful of salty water...</i></span></span> <span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><b><img alt="" class="mceWPmore mceItemNoResize" data-mce-src="http://betweenarock.co.uk/wp-includes/js/tinymce/plugins/wordpress/img/trans.gif" src="http://betweenarock.co.uk/wp-includes/js/tinymce/plugins/wordpress/img/trans.gif" title="More..." /></b></span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><i><sup>*The exact date depends on whether you have a preference for the Julian or Gregorian calendar</sup></i></span></span><br />
<br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">From
eyewitness reports, this is what it felt like to be caught up in the
most catastrophic flood ever to hit western Britain. Striking in January
1607*, its effects were felt all over the south-west of England,
extending over 570 km of coastline from Barnstaple to south Wales and as
far inland as Glastonbury (approximately 22km). Contemporary sources
put the death toll at over 2,000, though modern estimates have revised
this to 500 - 1000<sup>1</sup>. The water flow is said to have been so
fast "... that no gray-hounde could have escaped by running before
them." But what was the cause?</span></span><br />
<div class="mceTemp mceIEcenter">
<dl class="wp-caption aligncenter" data-mce-style="width: 310px;" id="attachment_1373" style="width: 310px;">
<dt class="wp-caption-dt"><br data-mce-bogus="1" /></dt>
</dl>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img alt="monwoodcut" class="size-medium wp-image-1373 " data-mce-src="http://betweenarock.co.uk/wp-content/uploads/2013/06/monwoodcut-300x194.gif" height="258" src="http://betweenarock.co.uk/wp-content/uploads/2013/06/monwoodcut-300x194.gif" width="400" /></td></tr>
<tr align="center"><td class="tr-caption"><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><span style="font-size: x-small;"><b>Contemporary woodcut depicting the scene in Monmouthshire on 30th January 1607.</b></span></span></span></td></tr>
</tbody></table>
<dl class="wp-caption aligncenter" data-mce-style="width: 310px;" id="attachment_1373" style="width: 310px;"><dd class="wp-caption-dd"><span style="font-family: Verdana,sans-serif;"></span><br /></dd></dl>
</div>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Prior
to a modern-day brush with fame, the Bristol Channel Floods were
variously attributed an extreme spring tide (the maximum extent of a
tidal range that occurs when the Earth, Moon and Sun are in alignment,
roughly every fortnight), a storm surge (high water levels associated
with a low pressure weather system) or a combination of both. This type
of coastal flooding is relatively common in the UK; a particularly
deadly occurrence in <a data-mce-href="https://en.wikipedia.org/wiki/North_Sea_flood_of_1953" href="https://en.wikipedia.org/wiki/North_Sea_flood_of_1953" target="_blank">1953 killed 307 people in East Anglia</a>.</span></span><br />
<br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">The
tsunami hypothesis was first proposed in 2002 by two academics (Haslett
& Bryant - see references 2,3 and 4), and followed up in a series
of subsequent papers by the same authors. Their re-interpretation of the
events unintentionally coincided with the devastating <a data-mce-href="http://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami" href="http://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami" target="_blank">Boxing Day tsunami of 2004</a>,
and so was perfectly poised to percolate the national consciousness.
Numerous media articles publicised the theory, and the floods were
featured in two BBC2 TV programmes (<a data-mce-href="http://www.youtube.com/watch?v=JtXJ6qNkic4" href="http://www.youtube.com/watch?v=JtXJ6qNkic4" target="_blank">Timewatch - "The Killer Wave of 1607"</a> and <a data-mce-href="http://www.bbc.co.uk/timewatch/britains-forgotten-floods.shtml" href="http://www.bbc.co.uk/timewatch/britains-forgotten-floods.shtml" target="_blank">"</a><a data-mce-href="http://www.bbc.co.uk/timewatch/britains-forgotten-floods.shtml" href="http://www.bbc.co.uk/timewatch/britains-forgotten-floods.shtml">Britain's Forgotten Floods"</a>).</span></span><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img alt="754586_a96910f6" class="size-medium wp-image-1433 " data-mce-src="http://betweenarock.co.uk/wp-content/uploads/2013/06/754586_a96910f6-300x225.jpg" height="225" src="http://betweenarock.co.uk/wp-content/uploads/2013/06/754586_a96910f6-300x225.jpg" style="margin-left: auto; margin-right: auto;" width="300" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">Flood
plaque in Goldcliff parish church, Newport. Reads "1606. On the XX day
of January even as it cames to pass it pleased God the flud did flow to
the edge of this same bras [brass], and in this parish theare was lost
5000 and od pownds besides xxii [22] people was in this parrish drown.".
Photo credit: Robin Drayton.</span></span></b></td></tr>
</tbody></table>
<dl class="wp-caption aligncenter" data-mce-style="width: 310px;" id="attachment_1433" style="width: 310px;">
<dt class="wp-caption-dt"><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"></span></span><br /></dt>
<dd class="wp-caption-dd"><b><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"></span></span></b><br /></dd></dl>
</div>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Of course, publicity is
not the mark of whether a theory is right or wrong, but proving this
particular watery dispute one way or the other has been hindered by a
couple of confounding conundrums: the subjectivity of historical sources
and the ambiguous nature of tsunami deposits.</span></span><br />
<br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">At the turn of the 17<sup>th</sup>
century, literacy levels in the UK were still relatively low. There
were no newspapers (or Twitter!), thus first-hand accounts are mostly
limited to privately printed pamphlets which tend to offer contrasting
reports. For example, the weather on the day in question is
conflictingly described as being "most fayrely and brightly spred",
"tempestuously moved by the windes" and in the grip of "a mightie
storm". The most supportive evidence for a tsunami comes from <i>"<a data-mce-href="http://website.lineone.net/~mike.kohnstamm/flood/jonespamphlet/godswarning.html" href="http://website.lineone.net/%7Emike.kohnstamm/flood/jonespamphlet/godswarning.html" target="_blank">Gods [sic] warning to the people of England</a>"</i>
, a publication funded by the Church. Its coverage of the event is
predictably zealous, describing the flood as a "universal, punishment by
Water."</span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">As geologists, the obvious solution would be to look to the rock record; however, tsunami deposits are <a data-mce-href="http://databases.eucc-d.de/files/documents/00001105_The%20identification%20of%20palaeo-tsunami%20deposits%20-%20a%20major%20challenge%20in%20coastal%20sedimentary%20research.pdf" href="http://databases.eucc-d.de/files/documents/00001105_The%20identification%20of%20palaeo-tsunami%20deposits%20-%20a%20major%20challenge%20in%20coastal%20sedimentary%20research.pdf" target="_blank">notoriously tricky to identify</a>
because their physical markers are incredibly hard to distinguish from
other sources of coastal flooding. Pro-tsunami authors Haslett &
Bryantt cite sand "storm" layers in sediments, erosion of salt marshes,
vortex pools, and imbricated boulder dumps as supporting evidence for a
'killer wave'; all features imply rapid deposition from a forceful flow
of water. Their proposed mechanism for the tsunami is either a submarine
landslide or earthquake in the sea between Ireland and Cornwall.</span></span><br />
<span style="font-family: Verdana,sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img alt="Imbricated boulders" class="size-medium wp-image-1430 " data-mce-src="http://betweenarock.co.uk/wp-content/uploads/2013/06/Simon-boulders-300x225.png" height="225" src="http://betweenarock.co.uk/wp-content/uploads/2013/06/Simon-boulders-300x225.png" style="margin-left: auto; margin-right: auto;" width="300" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><b>Prof. Simon Haslett atop imbricated boulders in the Severn Estuary.
Photo was taken during filming of the BBC2 programme “The Killer Wave”.
Source: http://profsimonhaslett.blogspot.co.uk</b></span></span></td></tr>
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<span style="font-family: Verdana,sans-serif;"></span><br />
<span style="font-family: Verdana,sans-serif;"><br /></span>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Perhaps the
most compelling evidence against the tsunami hypothesis is that severe
flooding in Norfolk is documented on the same day. Most tsunami models
agree that it is geometrically impossible for the effects of a tsunami
to wrap around the entire coast of England. It seems like the most
plausible cause of the floods is a storm surge imposed on an unusually
high spring tide. Indeed, the Severn Estuary has the <a data-mce-href="http://jncc.defra.gov.uk/default.aspx?page=2066" href="http://jncc.defra.gov.uk/default.aspx?page=2066">second highest tidal range in the world</a>. The contemporary reports of windstorms driving up the seas is reminiscent of <a data-mce-href="https://www.youtube.com/watch?v=1nBoU_YqpaE" href="https://www.youtube.com/watch?v=1nBoU_YqpaE">storm surges in New Orléans</a> during Hurricane Katrina in 2005.</span></span><br />
<br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Regardless
of the cause, it is important to consider the impact that a repeat of
the 1607 floods would have today, in order to mitigate against future
disasters. The Severn estuary is home to the (active) Hinkley Point and
(closed) Oldbury nuclear power stations, and is the proposed site of the
<a data-mce-href="http://www.guardian.co.uk/business/2013/jun/10/severn-tidal-power-barrage-plans-mps" href="http://www.guardian.co.uk/business/2013/jun/10/severn-tidal-power-barrage-plans-mps" target="_blank">controversial Severn Tidal Barrage</a>.
Other notable infrastructure includes two motorway bridges, a working
port (Avonmouth) and half a million people living in Bristol alone! One
risk assessment puts the cost of such an event at £7 - 13 billion<sup>1</sup>.</span></span><br />
<br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">In
the wake of the 2004 Boxing Day tsunami, the UK government recognised
they did not have a quantitative assessment of threat to the UK. This
was despite another infamous tsunami study<sup>5</sup> (the results of
which are now viewed with scepticism) which predicted that a landslide
off La Palma would generate waves "higher than Nelson's column" and
smash into the west coast of Britain - <a data-mce-href="http://www.dailymail.co.uk/news/article-69105/Britain-faces-tidal-wave-threat.html" href="http://www.dailymail.co.uk/news/article-69105/Britain-faces-tidal-wave-threat.html" target="_blank">mass media loved it</a>. Happily for us, the <a data-mce-href="http://archive.defra.gov.uk/environment/flooding/risk/tsunami.htm" href="http://archive.defra.gov.uk/environment/flooding/risk/tsunami.htm" target="_blank">government reports</a>
conclude "tsunami-type events [affecting the UK] are unlikely to exceed
those anticipated for major storm surges", and "all major centres of
development on coasts and estuaries have defences that have been
designed to withstand such surge waves."</span></span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img alt="hazards6" class="size-full wp-image-1439 " data-mce-src="http://betweenarock.co.uk/wp-content/uploads/2013/06/hazards6.jpg" height="204" src="http://betweenarock.co.uk/wp-content/uploads/2013/06/hazards6.jpg" width="252" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><b>Should we have these in Bristol City Centre?</b></span></span></td></tr>
</tbody></table>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"></span></span> </span></span><br />
<br />
<div data-mce-style="text-align: left;" style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Despite their assurances, a small part of me feels pretty smug about a living and working a good 50 metres above sea level!</span></span><br />
<br />
<span style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;">Charly Stamper </span></span></div>
<div data-mce-style="text-align: left;" style="text-align: left;">
<br /></div>
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><b>References</b></span></span><br />
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">[1]<a data-mce-href="https://support.rms.com/Publications/1607_Bristol_Flood.pdf" href="https://support.rms.com/Publications/1607_Bristol_Flood.pdf" target="_blank"> "1607 Bristol Channel Floods: A 400-Year Retrospective" - Online publication by Risk Management Solutions. </a></span></span><br />
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">[2]
Bryant EA & Haslett SK (2007) Catastrophic Wave Erosion, Bristol
Channel, United Kingson: Impact of Tsunami? The Journal of Geology: 115,
p. 253-269.</span></span><br />
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">[3] Bryant EA & Haslett SK (2002) Was the AD 1607
coastal flooding event in the Severn Estuary and Bristol Channel (UK)
due to a tsunami? Archaeology in the Severn Estuary. 13: 163 - 167.</span></span><br />
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">[4]
Haslett & Bryant (2004) The AD 1607 coastal flood in the Bristol
Channel and Severn Estuary: historical records from Devon and Cornwall
(UK). Archaeology in the Severn Estuary. 13: 81 - 89.</span></span><br />
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">[5] Ward, SN
& Day, SJ (2001) Cumbre Vieja Volcano; potential collapse and
tsunami at La Palma, Canary Islands. Geophys. Res. Lett. 28-17,
3397-3400.</span></span></div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-25683867132363307012013-06-04T11:40:00.002-07:002013-06-04T11:40:42.317-07:00The building stones of Clifton - a walking trail<div dir="ltr" style="text-align: left;" trbidi="on">
<div dir="ltr" style="text-align: left;" trbidi="on">
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<div class="column" style="text-align: center;">
<span style="font-size: large;"><span style="font-family: Verdana,sans-serif;"><b> Building Stones of Clifton
- <span style="font-size: large;">A</span> Walking Trail</b></span></span></div>
<div class="column" style="text-align: center;">
<span style="font-size: large;"><span style="font-family: Verdana,sans-serif;"><b> </b></span></span><span style="font-size: large;"><span style="font-family: Verdana,sans-serif;"><span style="color: #45818e;"><span style="font-size: small;"><b><span style="font-style: italic;">A thirty-minute ramble through 350 million years of</span></b></span></span></span><span style="color: #45818e;"><span style="font-size: small;"><b><span style="font-family: Verdana,sans-serif;"><span style="font-style: italic;"> geological time
</span></span> </b></span></span></span></div>
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<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj29zNAfx-aeFD2qNAte9DRGvxpjGZTQFDPnpbF2qzxisLj2yMFstXWmPTY7D-pal1hQ5yj2saExftiVNRI7qnmEmp7uzCRJzVtDOFC3XN1WCPmwTgtExqVWXZVzfurI4RAYKQDzxu2iByT/s1600/CBS_map_CCS2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="283" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj29zNAfx-aeFD2qNAte9DRGvxpjGZTQFDPnpbF2qzxisLj2yMFstXWmPTY7D-pal1hQ5yj2saExftiVNRI7qnmEmp7uzCRJzVtDOFC3XN1WCPmwTgtExqVWXZVzfurI4RAYKQDzxu2iByT/s320/CBS_map_CCS2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: 'IwonaMedium'; font-size: 8.000000pt;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><b>The trail includes five stops within Clifton and is approximately
1.5km long (blue trail).<br />
Optional sixth stop is an additional 1 km (pink trail).
Begin at Clifton Hill House, Lower Clifton Hill, BS8 1BX</b></span></span>.
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<b><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Bedrock geology
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglZbOSQ1hRQTEl8_mthZuZj7EvW7XZ9iatOn0W7SDjAF3-JvURe-iID6X7q7aiLf0Ul9OalDbb-kbNUg1eyNvKKFsEWGjJNz2AatHetIhtakFtUoalKlOs44pg0vncCCNyfuz-76i7MP5W/s1600/bristol_log.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglZbOSQ1hRQTEl8_mthZuZj7EvW7XZ9iatOn0W7SDjAF3-JvURe-iID6X7q7aiLf0Ul9OalDbb-kbNUg1eyNvKKFsEWGjJNz2AatHetIhtakFtUoalKlOs44pg0vncCCNyfuz-76i7MP5W/s320/bristol_log.jpg" width="117" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b>Bedrock geology of Clifton</b></td></tr>
</tbody></table>
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<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">The oldest rocks beneath
Clifton are Devonian Old Red
Sandstone, lower Carboniferous
limestones and sandstones,
and Upper Carboniferous Coal
Measures. These are sediments
deposited during a long period
of fluctuating sea level. In the
Permian period, formation of the
supercontinent <span style="font-style: italic;">Pangaea </span>caused
uplift of existing landmasses
which were consequently subject
to strong erosional forces. The
resulting detritus created the next
generation of bedrock, and so the
older sediments are unconformably
overlain by Triassic conglomerates
and sandstones, and Rhaetic
limestones.
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<b><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Site 1 - Clifton Hill House</span></span></b> </div>
<div class="column" style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"></span></span><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Bath Stone (oolitic limestone) - Jurassic
</span></span>
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<span style="color: blue;"><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><span style="font-style: italic;">Start the trail at Clifton Hill House at the top of Lower Clifton Hill </span></span></span></span><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgynHm0csFm-cHwYXhY_EenOv9Wpe8I61Fj1auGxc5Yt3kY-KrBckk92BO9MyqYw_cJL-ea2LbVk_WyIk3XqFQEOQgpPKbXJG2eYV9mlpeZw5CW-k2xKiYRLp_l2h8EIkRIVvbuBv4wWwU4/s1600/CHH.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="151" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgynHm0csFm-cHwYXhY_EenOv9Wpe8I61Fj1auGxc5Yt3kY-KrBckk92BO9MyqYw_cJL-ea2LbVk_WyIk3XqFQEOQgpPKbXJG2eYV9mlpeZw5CW-k2xKiYRLp_l2h8EIkRIVvbuBv4wWwU4/s400/CHH.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><b>Clifton Hill House - Jurassic oolitic limestone
</b></span></span></td></tr>
</tbody></table>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Built in the 1740s, this former merchant’s mansion is now
part of a hall of residence for the University of Bristol. The
front of the building is faced with cream-coloured oolitic
limestone, a rock not native to Clifton; it was extensively
quarried in (and is eponymous to) Bath when it became
fashionable in the 18th century. Bath Stone was deposited
in a tropical shallow marine environment, similar to that of
the Bahamas today. The rock comprises millimetre-sized
‘ooids’, small lithic grains coated in concentric rings of
aragonite (preserved as calcite) mud. Other features, such
as cross-bedding and calcite veining, are neatly captured
in the end stone.
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<b><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Site 2 - Goldney House
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<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Brandon Hill Grit - Upper Carboniferous
</span></span></div>
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<span style="font-size: x-small;"><span style="color: blue;"><span style="font-family: Verdana,sans-serif;"><span style="font-style: italic;">Continue Clifton Hill and cross the road at Constitution Hill [150m] </span></span></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><span style="font-style: italic;"> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgup8MaC6mhtKruYsz_tE25aXyYipYI0rpOr4nuIYsikt3Kcih76ErRpSwDMDnIQ2Tf42ieJge9_0ssgevfdfKSGeKmGJiKySudbuTDIjxL-WFcHX7CGDYJheInhXN0k-eBQes1cvXlAwPx/s1600/Goldney_BHG.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgup8MaC6mhtKruYsz_tE25aXyYipYI0rpOr4nuIYsikt3Kcih76ErRpSwDMDnIQ2Tf42ieJge9_0ssgevfdfKSGeKmGJiKySudbuTDIjxL-WFcHX7CGDYJheInhXN0k-eBQes1cvXlAwPx/s400/Goldney_BHG.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: x-small;">Goldney House coach house - Brandon Hill Grit
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<div style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Goldney House is also part of a university hall of resi-
dence, although the main building is a modern addition to
the early 18th century coach house and other outbuildings.
The coach house wall is accessible from the pavement
and is an irregular patchwork of Brandon Hill Grit, a
coarse Upper Carboniferous quartzite sourced from nearby
Brandon Hill. The rock was laid down as a deltaic sand
coevally to the limestones of the Avon Gorge; coarser
horizons in some blocks are evidence for ephemeral stream
channels. Its distinctive pink-red colouration is staining
from the overlying Triassic sediments. </span></span></div>
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<b><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Site 3 - Caledonia Place
</span></span></b><br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Pennant Sandstone - Upper Carboniferous
</span></span><br />
<span style="font-size: x-small;"><span style="color: blue;"><span style="font-family: Verdana,sans-serif;"><span style="font-style: italic;">Continue on Lower Clifton Hill as it becomes Regent Street. Walk into
Clifton Village and turn left along Royal York Crescent. To the south is
Dundry Hill [600m]. Walk all the way along the terrace, turn right at
the end into Wellington Terrace, and then second right into Caledonia
Place [500m].</span></span></span></span><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhrceKHxF0zsvfzQ-ZGGJwZlhsb0WwpHCPBp5xMKBHXHK_jK9VTIOSel-xT27NC-1pXzsUAWcwWwO2zHZ4oaOVSJngF8nStZMrO3oyNb76Hul0np_BA_xrT8LHW6FNO-krzBbALtK4TUKr/s1600/pennant.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhrceKHxF0zsvfzQ-ZGGJwZlhsb0WwpHCPBp5xMKBHXHK_jK9VTIOSel-xT27NC-1pXzsUAWcwWwO2zHZ4oaOVSJngF8nStZMrO3oyNb76Hul0np_BA_xrT8LHW6FNO-krzBbALtK4TUKr/s400/pennant.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><b>Caledonia Place - Pennant Sandstone mounting blocks
</b></span></span></td></tr>
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<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Though prevalent as a building stone in the city centre of
Bristol, Pennant Sandstone is not as common in Clifton.
This grey-coloured sandstone is rich in feldspar and
micas, and was deposited in shallow waters in the Coal
Measures. The poor cementation between individual
grains made the sandstone easy to quarry; however, this is
counterbalanced by its relative fragility and vulnerability
to weathering. In Caledonia Place it has been employed
as mounting blocks (to aid Victorian residents’ ascent into
horse-drawn carriages). </span></span><br />
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<b><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Site 4 - Clifton Suspension Bridge
</span></span></b><br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">New Red Sandstone - Triassic
</span></span><br />
<span style="font-size: x-small;"><span style="color: blue;"><span style="font-family: Verdana,sans-serif;"><span style="font-style: italic;">Retrace your steps out of Caledonia Place and continue along Wellington
Terrace, then Sion Hill [300m] </span></span></span></span><br />
<span style="font-size: x-small;"><span style="color: blue;"><span style="font-family: Verdana,sans-serif;"><span style="font-style: italic;"> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0ZIOSu8u233KlHR0qoZeTyumjVAv33KGuWFj28UYXxGg1AdyhjtZ3vC7KSoqVS08ycb_A1YypjHGMcQp27Wg6Mu8d73cJA36BIixIN4xWqnV8jU1KIC3_vWbnt1bdncs56SUfx-TkDAv4/s1600/bridge.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="183" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0ZIOSu8u233KlHR0qoZeTyumjVAv33KGuWFj28UYXxGg1AdyhjtZ3vC7KSoqVS08ycb_A1YypjHGMcQp27Wg6Mu8d73cJA36BIixIN4xWqnV8jU1KIC3_vWbnt1bdncs56SUfx-TkDAv4/s400/bridge.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: x-small;">New Red Sandstone facings at the Clifton Suspension Bridge
</span></b></td></tr>
</tbody></table>
</span></span></span></span><br />
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<br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Clifton Suspension Bridge is Bristol’s most iconic land-
mark and was designed by Isambard Kingdom Brunel
in 1831 (but completed posthumously in 1864) to span
the chasm between the Carboniferous limestone cliffs of
the Avon Gorge. The base of the gothic towers are
attractively faced with New Red Sandstone. Its distinctive
red colouration reveals its subaerial formation in the
deserts of Pangaea and layering from ancient sand dunes
is preserved as cross-bedding.
</span></span></div>
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<b><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Site 5 - The Observatory
</span></span></b></div>
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<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Carboniferous Limestone - Lower Carboniferous
</span></span></div>
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</span></span><br />
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<span style="font-size: x-small;"><span style="color: blue;"><span style="font-family: Verdana,sans-serif;"><span style="font-style: italic;">Follow the short footpath up the hill from the Bristol-side toll booth
[200m] </span></span></span></span></div>
<div style="text-align: left;">
<span style="font-size: x-small;"><span style="color: blue;"><span style="font-family: Verdana,sans-serif;"><span style="font-style: italic;"> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhT7hyphenhyphenvly4GiaAaAMyH5nHbr0xw_7xRpWwIBZ2vQwdwIRYIY3lsWlaWHeYGCt2PmascsW15inXbQ9Cd6azXhBpl8kbYVyJ8IzryQsJ0fU-DqP6OPtj4uysT_zESJFZCEWxCnZNQtKhiPmsr/s1600/Observatory.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="175" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhT7hyphenhyphenvly4GiaAaAMyH5nHbr0xw_7xRpWwIBZ2vQwdwIRYIY3lsWlaWHeYGCt2PmascsW15inXbQ9Cd6azXhBpl8kbYVyJ8IzryQsJ0fU-DqP6OPtj4uysT_zESJFZCEWxCnZNQtKhiPmsr/s400/Observatory.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b>The Observatory - Carboniferous Limestone
</b></span></td></tr>
</tbody></table>
</span></span></span></span></div>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">
</span></span><br />
<div style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Originally built as a mill in the late 18th century,
Observatory Tower was purchased over fifty years later
by a local artist who installed a telescope and camera
obscura (to project panoramic exterior views onto a screen).
The rounded rubble walls comprise fossiliferous blocks of
Carboniferous Limestone hued from the gorge, and provide
a reminder of a time when the Avon region was submerged
beneath a balmy tropical ocean. Descend to ‘Giant’s Cave’
beneath The Observatory to further explore the strata of
the Gorge. </span></span></div>
<div style="text-align: left;">
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<div class="column">
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<b><span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Site 6 [optional] - The Cumberland Basin
</span></span></b></div>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">
</span></span><br />
<div style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">Cornish granite - Lower Permian
</span></span></div>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">
</span></span><br />
<div style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><span style="font-style: italic;"><span style="color: blue;"><span style="font-size: x-small;">For a longer addition to your excursion, retrace your steps towards the
Avon Gorge Hotel and take the Zig Zag footpath down to The Portway.
Turn left and walk towards Bristol City Centre. Take care when crossing
the busy road - it is best to walk over the pedestrian footbridge which
begins in Granby Hill [∼1km]</span></span>. </span></span></span></div>
<div style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><span style="font-style: italic;"> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiK8nJyzl6U5PF5n7KM_buGiFrv0dDmPRvry3SVvrPWK6gFwOgVh6DXdNu8YXwZM7NvpCuSaNe63HpYgL66po1TlFpU5hLgjVAr6Aj5XmEBsSyKHnOgl1EHDVo583-F-9UkXWQFbk-esBP_/s1600/Cumb_basin.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiK8nJyzl6U5PF5n7KM_buGiFrv0dDmPRvry3SVvrPWK6gFwOgVh6DXdNu8YXwZM7NvpCuSaNe63HpYgL66po1TlFpU5hLgjVAr6Aj5XmEBsSyKHnOgl1EHDVo583-F-9UkXWQFbk-esBP_/s400/Cumb_basin.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b>Cumberland Basin - Bodmin Granite
</b></span></td></tr>
</tbody></table>
</span></span></span></div>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">
</span></span><br />
<div style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;">The Cumberland Basin was excavated in 1809 when
the River Avon was diverted to form a floating harbour
and granite is used as capping material on the channel
walls. Petrolographic analysis has shown it to be Bodmin
Granite, part of the <a href="http://en.wikipedia.org/wiki/Cornubian_batholith">Cornubian batholith</a> that is exposed
throughout Cornwall and the Channel Island. This igneous
rock formed a result of a huge mass of magma intruding
into the crust during Variscan orogeny (∼275Ma). Though
the surface has weathered to a smooth finish, individual
crystals of grey quartz, white plagioclase and pinky-
orange orthoclase feldspars, and dark-coloured biotite
mica can still be identified. </span></span></div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: small;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">Charly Stamper </span></span></span></span></div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
<b><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">References</span></span></b></div>
<div style="text-align: left;">
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">
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<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">- Jones D (1992) A History of Clifton. Phillimore, Chichester.</span></span><br />
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">- Mowl T (1991) To build the second city: Arcitects and craftsmen of Georgian Bristol. Redcliffe Press Ltd, UK. </span></span><br />
<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">- Savage RJG (1988) Buildling Stones of Clifton. Proceedings
of the Bristol Naturalists’ Society, 48: 85-104.</span></span></div>
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Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-88106054292008853962013-05-23T03:09:00.000-07:002013-05-26T10:43:33.611-07:00Box Rock Circus - official opening<div class="separator" style="clear: both; text-align: center;">
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<span style="font-family: Verdana, sans-serif;"><b><span style="line-height: 115%;">BOX ROCK CIRCUS
OFFICIALLY OPENED BY PROFESSOR IAIN STEWART</span></b><span style="line-height: 115%;"><o:p></o:p></span></span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjltATSn4xNxFhCVViSvyccC7AFERVU4NDn7VEYUabqfXj0uNDDlYGv6HpSf4o7z3yhLWz9wNiME4Rp71NrCd3GtljBDGDpjkiffVX6pwPrKv_biVZuVpVnKic3nKZbDq_AiS-BuKTiPqvv/s1600/25+With+the+BBC%252C+Pauline+Lyons+and+Elizabeth+Devon.+%25282%2529.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjltATSn4xNxFhCVViSvyccC7AFERVU4NDn7VEYUabqfXj0uNDDlYGv6HpSf4o7z3yhLWz9wNiME4Rp71NrCd3GtljBDGDpjkiffVX6pwPrKv_biVZuVpVnKic3nKZbDq_AiS-BuKTiPqvv/s400/25+With+the+BBC%252C+Pauline+Lyons+and+Elizabeth+Devon.+%25282%2529.JPG" width="400" /></a></div>
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<span style="font-family: Verdana, sans-serif; font-size: x-small;">Photo credits Charles Hiscock</span></div>
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<span style="font-family: Verdana, sans-serif; line-height: 115%;">On a rather
damp Tuesday May 14<sup>th</sup> 2013 a large number of people from the village of
Box, near Corsham, Wiltshire, pupils from the local schools, members of the
Bath Geological Society, and many other interested folk gathered at the Selwyn
Hall recreation field for the official opening of the Box Rock Circus. The
Circus, the brainchild of local geologist and Earth Science Educator Elizabeth
Devon, which had been unofficially unveiled on its completion on the 9<sup>th</sup>
August 2012, has since received an interpretation board entitled ‘Box Rock
Circus - A magical circle of rocks, fossils and minerals’ and the fossil moulds
inserted into a different position, making them more accessible to the smallest
child. <o:p></o:p></span><br />
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<span style="font-family: Verdana, sans-serif; line-height: 115%;"> Amongst a
colourful array of umbrellas, Elizabeth Devon and the Chairman of the Parish
Council welcomed everyone to the event after which Professor Iain Stewart,
Professor of Geoscience Communications at the University of Plymouth and well
known television presenter officially opened the Box Rock Circus. He
enthusiastically praised all those who had the foresight to plan and carry out
the project and the referred to the ages and conditions of formation of the
rock monoliths. He also suggested that other towns and villages should follow
the example of Box. BBC Wiltshire Sound was present to record the event,
interviewing the enthusiastic pupils of Box Primary School. Following the opening
of the Circus by Professor Stewart, a buffet lunch had been prepared for
invited guests in the Box Pavilion.<o:p></o:p></span><br />
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<span style="font-family: Verdana, sans-serif;"><span style="line-height: 115%;">A full description of the rocks and specimens can be found in
the Avon RIGS blog for 2012 - </span><a href="http://avonrigsoutcrop.blogspot.co.uk/2012/08/box-rock-circus.html">http://avonrigsoutcrop.blogspot.co.uk/2012/08/box-rock-circus.html</a>
<span style="line-height: 115%;">when the Circus was unveiled
following its completion. For more information go the website - <a href="http://www.boxrockcircus.org.uk/">www.boxrockcircus.org.uk</a></span></span><br />
<span style="color: #0000ee; font-family: Verdana, sans-serif;"><u><br /></u></span><span style="font-family: Verdana, sans-serif;"><span style="line-height: 115%;"><a href="http://www.boxrockcircus.org.uk/"></a></span></span>
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<span style="line-height: 115%;"><span style="font-family: Courier New, Courier, monospace;">Charles Hiscock </span><span style="font-family: Verdana, sans-serif;"><o:p></o:p></span></span></div>
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-91674465839722439892013-05-14T12:28:00.001-07:002016-12-24T03:35:21.286-08:00RIGS of the month [May] - Troopers Hill, Bristol<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="font-size: x-large;"><b>RIGS of the Month - May</b></span><br />
<span style="font-size: x-large;"><b><span style="color: #0c343d;"><span style="font-size: x-large;">Troopers Hill, Bristol</span></span></b></span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM2A-F2VV08fs53jtc8bo2Mz9DcSwV6klSzL4_EFQUuBCzdGlprYCjtQskzaseiDv1m_RqhUPnWIQLCVtPXTMOouE7OeU2Hsi22B-c2JekXWjyUwHOdhvyW9ZP6PXye8eAFcgSM3_Vw7O0/s1600/Screen+Shot+2013-05-14+at+20.04.00.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="257" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM2A-F2VV08fs53jtc8bo2Mz9DcSwV6klSzL4_EFQUuBCzdGlprYCjtQskzaseiDv1m_RqhUPnWIQLCVtPXTMOouE7OeU2Hsi22B-c2JekXWjyUwHOdhvyW9ZP6PXye8eAFcgSM3_Vw7O0/s400/Screen+Shot+2013-05-14+at+20.04.00.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;"><b>Fig. 1: Location of Troopers Hill, St George, Bristol. Postcode BS5 8BL.</b></span></span></td></tr>
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: x-small;"><i><a href="http://www.troopers-hill.org.uk/directions.pdf">Click here for directions and publ<span style="font-size: x-small;">ic transport options (external website)</span></a></i></span></span></div>
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<span style="font-size: small;"><b>SITE SPECIFIC INFORMATION </b></span><br />
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<span style="font-size: small;"><b>Location: </b></span><span style="font-size: small;"><span class="pp-headline-item pp-headline-address" dir="ltr">BS5 <span style="font-size: small;">8B<span style="font-size: small;">L</span></span></span><b> </b></span></div>
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<span style="font-size: small;"><b>Accessibility:</b><span style="font-size: small;"> </span></span>The entrance at Malvern Road provides the easiest access for those with limited mobility<span style="font-family: sans-serif;">.</span> Some of the slopes on this path may mean that some wheelchair users need assistance. The remainder of the paths on the hill are unsurfaced.</div>
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<span style="font-size: small;"><b>Topography:</b> Hilly,<span style="font-size: small;"> <span style="font-size: small;">gra<span style="font-size: small;">ssed foo<span style="font-size: small;">tpaths</span></span></span></span></span><br />
<span style="font-size: small;"><b>Restr<span style="font-size: small;">ictio<span style="font-size: small;">ns</span></span>:</b> </span>Troopers Hill is owned and managed by Bristol City Council, there is free unrestricted access.</div>
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<i><span style="font-family: "verdana" , sans-serif;"><span style="font-size: x-small;">This article has been adapted from Andrew's post on the <a href="http://www.troopers-hill.org.uk/">Friends of Troopers Hill website</a> - the original version <a href="http://www.troopers-hill.org.uk/geology/RocksTroopersHill.pdf">can be accessed here</a> and includes a detailed strati<span style="font-size: x-small;">graphic log</span>. Eil<span style="font-size: x-small;">ene Stonebri<span style="font-size: x-small;">d<span style="font-size: x-small;">ge also contr<span style="font-size: x-small;">i<span style="font-size: x-small;">buted a great deal <span style="font-size: x-small;">of material to the site<span style="font-size: x-small;"> (<a href="http://www.troopers-hill.org.uk/geology.htm">see section on </a><span style="font-size: x-small;"><a href="http://www.troopers-hill.org.uk/geology.htm">g</a><span style="font-size: x-small;"><a href="http://www.troopers-hill.org.uk/geology.htm">eology</a>) and <span style="font-size: x-small;">w<span style="font-size: x-small;">rote an accompanying leaf<span style="font-size: x-small;">let which can be <span style="font-size: x-small;">downloaded for free - link at the bottom of this post.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></i></div>
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<span style="font-family: "verdana" , sans-serif;">Troopers Hill’s geology is unusual in Bristol. Much of the city lies on
Carboniferous Limestone, but Troopers Hill is dominated by sandstone of
the Pennant Measures which are sedimentary rocks formed in tropical
swamps some 300 million years ago. In places, the sandstone can be seen
on the surface, both as natural outcrops and old quarry faces.
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The combination of sandstone and local industry has resulted in acid
soils, which are rare in Bristol. This has encouraged a wealth of plants
to flourish, that are found nowhere else in the City. <br /><br />Much of
the shape of the hill is the result of quarrying for the sandstone which
was used as building stone throughout Bristol. The largest quarry was
the gully in the centre of the hill which was worked until the end of
the nineteenth centuary. The humps and bumps above Troopers Hill Rd are
where the unsuitable stone was tipped.<br /><br />As well as sandstones the
Pennant Measures include mudstones, shales, clay and coal seams. In the
past coal has been dug where it outcroped on the hill and both fireclay
and coal have been taken from deep mines under the hill.
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">Troopers Hill is made up of a thick pile of layers of rock which must have been<br />
well known to the generations of miners and quarrymen who extracted coal, fireclay and sandstone from them for centuries. However, much of that knowledge has been lost and no one now is quite sure what lies under the hill.</span></span></div>
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">There are at least 9 coal seams there and some of these were exposed at the surface. Local geologist Tom Fry recalled one seam 5-6ft. thick revealed on the west side of the hill in 1968, but all the other seams are probably much thinner. He also remembered that a very thin seam was worked by unemployed<br />
men in 1913 on the hill near the bottom of Troopers Hill Road, where sadly a friend of his died after the shaft collapsed.</span></span><span style="font-family: "verdana" , sans-serif;"></span><span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;"> </span></span></div>
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">The rocks are sandstone, mudstone, coal and clay, and they all dip to the south at between 25 and 45
degrees. They belong to the Upper Carboniferous Coal Measures, and are near the base of the
Pennant Sandstone. The rock types, structures and fossils suggest that they were formed when the
area was covered by a forested swamp. At this time (about 300 million years ago) the area is thought
to have been near the equator with a tropical climate. The rocks were next squeezed by huge forces,
which crumpled them into a large arched fold that runs east-west through Kingswood. The Trooper's
Hill rocks lie on the south side of this structure. </span></span></div>
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">The sandstone at Troopers Hill is called Pennant, since the early geologists took the name traditionally used by miners and quarrymen. The Pennant forms a thick mass of sandstone in the middle of the local Coal Measures around Bristol, as well as in the Forest of Dean and South Wales. The name is thought to have been derived from the Welsh words <i>penn</i> and <i>nant</i>, meaning head of the valley.The rock is well exposed in the Gully Quarry, just south of Trooper's Hill chimney.</span></span><br />
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">The sandstones exposed on the north side of the Gully display cross bedding, indicating that the original sand grains were carried by running water in rivers. </span></span><br />
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">On the south of the Gully the rocks are coarser grained with coal pebbles and fossil imprints of tree trunks, suggesting that at times the water was flowing fast enough to erode
sediment and move large pieces of wood.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9U4s7jXEZk6gyI7XtHfAzQhBaOJqTdUnyH29GYHlQ65tfo3qw4IASmpFFVOIt99yfvCf3PjA1-BDAPEaoOPpMjswdOW2mRl9RLH1r7X7aPhW8pbcwT6T3_WFcaaOk0in1glbvExUYXcLA/s1600/Screen+Shot+2013-05-14+at+20.16.36.png" style="margin-left: auto; margin-right: auto;"><img border="0" height="228" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9U4s7jXEZk6gyI7XtHfAzQhBaOJqTdUnyH29GYHlQ65tfo3qw4IASmpFFVOIt99yfvCf3PjA1-BDAPEaoOPpMjswdOW2mRl9RLH1r7X7aPhW8pbcwT6T3_WFcaaOk0in1glbvExUYXcLA/s320/Screen+Shot+2013-05-14+at+20.16.36.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-family: "verdana" , sans-serif;">Fossilised wood in Pennant Sandstone. Photo credit: Steve England</span></b></td></tr>
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">Pennant was quarried at many sites in the local coalfields and provided stone for thousands of
buildings, including the chimney at the top of Trooper's Hill. It sometimes splits into thin slabs which
were much used for paving, kerbs, steps, gravestones, and, in earlier times, for roofing.
</span></span><span style="font-family: "verdana" , sans-serif;"></span>
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<b><span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">
</span></span></b></div>
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<b><span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">Mudstone
</span></span></b><br />
<span style="font-family: "verdana" , sans-serif;">
</span><span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">The mudstones were known as duns by the miners. They are less well exposed but can be seen in the
paths to the south of Troopers Hill, and they indicate a period when the waters in the swamps must
have been still. They had no commercial value. </span></span><br />
<br />
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;"><b>Coal</b> </span></span><br />
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">The miners called the coal
</span><span style="font-size: 12pt;">seams “veins” and gave them
</span><span style="font-size: 12pt;">names which were used at each
pit in the area where they were
found, from Newton St Loe,
near Bath, to St Phillips Marsh,
in Bristol. Some seams thinned
to nothing and others split,
which made the naming
uncertain in places. Each seam
is thought to be the compressed
remains of deposits of peat,
built up from the remains of the
trees of the forest.</span> </span><br />
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<br />
<span style="font-family: "verdana" , sans-serif;">Crewe's Hole Pit was sited at<span style="font-size: 12pt;"> the south end of Troopers Hill, and is marked by the remains of he chimney of the mine engine house. Air Balloon Pit was next to Air Balloon Road, about half a
mile north of the Hill. The mining geologist John Anstie was employed to gather information on all
the local coal mines for the Royal Commission on Coal. He collected some details of what had been
found in these pits, although both were disused when he visited the area in about 1870 and he was
concerned that the information might not be completely reliable. </span><span style="font-size: 12pt;">He also observed that “the outcrops
</span><span style="font-size: 12pt;">of the Devil's seam, Buff and Parrot seams, follow parallel lines about 500 yards to the north of those
</span><span style="font-size: 12pt;">of the Millgrit and Rag seams ... (and at) ..Trooper's Hill .. the shallow works on all of them are
clearly traceable.” He noted that the Air Balloon Pit only worked for three </span><span style="font-size: 12pt;">or four years as the seams
were too variable to be worked economically.</span><span style="font-size: 12pt;"> </span></span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeFU32YArYT6GAmmubfPFBEpFUKrllj60JQlNSpQ2J7rmyNGpQZdugS-ZdEo3VsY2T1QBjt0UIl9zkwXfD1C8GLWk5CTXb7IJoRrMiv_6xKqgOrxhb55lSPCh2ey21DsLRXO6dNo5xxXFL/s1600/Screen+Shot+2013-05-14+at+20.19.56.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="208" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeFU32YArYT6GAmmubfPFBEpFUKrllj60JQlNSpQ2J7rmyNGpQZdugS-ZdEo3VsY2T1QBjt0UIl9zkwXfD1C8GLWk5CTXb7IJoRrMiv_6xKqgOrxhb55lSPCh2ey21DsLRXO6dNo5xxXFL/s320/Screen+Shot+2013-05-14+at+20.19.56.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b><span style="font-family: "verdana" , sans-serif;">The engine house in Troopers Hill Rd, c. 1914. <span style="font-size: x-small;">Rep<span style="font-size: x-small;">roduced by kind permission of the Bristol Reference Library.</span></span></span></b></span></td></tr>
</tbody></table>
<br />
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">Tom Fry was brought up near Troopers Hill and knew the area very well. He recalled one seam 5-6ft.
thick revealed on the west side of the hill in 1968 before the council used the area as a rubbish tip.
Tom recalled that in around 1910, his father used to warn him of the dangers of the hill, telling him
that it was all undermined. His father worked in the Fireclay Mine. Tom also recalled the collapse of
an old sloping shaft in the floor of the main quarry, the sides of which had been walled with mortared
stone, and that he could trace the sites of at least six shallow mines on the Hill.
</span></span>
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<b><span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">Fireclay</span></span></b><span style="font-family: "verdana" , sans-serif;"> </span></div>
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<span style="font-family: "verdana" , sans-serif;">
</span><span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">Fireclay is usually found beneath a coal seam and is basically the clay soil where the trees grew
which provided the peat deposits. Fireclay is rich in clay minerals which means that when fired into
bricks or tiles, they can withstand high heat. Tom Fry noted that the Troopers Hill fireclay was used
to produce high quality terra cotta tiles that were used in many local buildings. </span></span></div>
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<span style="font-family: "verdana" , sans-serif;">
</span><span style="font-family: "verdana" , sans-serif;"><span style="font-size: 12pt;">Three fireclay beds are known to have been worked beneath Trooper's Hill. </span></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSvGL_87bjVt1unCwOXfoaACx47WLvUZHLC22EBFPUf6cFxugWTRJixqOs-pg0kdyqNEsLb67ahTJEhQ4QecJU-h1PzWQc6syg_ivLG-5BKZolV6c9brWYmVKRb-Ngf3THjTzhUw7pLSOr/s1600/Screen+Shot+2013-05-14+at+20.22.41.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="243" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSvGL_87bjVt1unCwOXfoaACx47WLvUZHLC22EBFPUf6cFxugWTRJixqOs-pg0kdyqNEsLb67ahTJEhQ4QecJU-h1PzWQc6syg_ivLG-5BKZolV6c9brWYmVKRb-Ngf3THjTzhUw7pLSOr/s320/Screen+Shot+2013-05-14+at+20.22.41.png" width="320" /></a></div>
<div style="font-family: 'courier new', courier, monospace;">
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<div style="font-family: 'courier new', courier, monospace;">
Andrew Mathieson</div>
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<span style="font-family: "verdana" , sans-serif;"><b>Further reading</b></span></div>
<div class="separator" style="clear: both; font-family: 'courier new', courier, monospace; text-align: center;">
<a href="http://www.troopers-hill.org.uk/leaflets/index.htm"><img alt="" border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3-UmYW6QWyhFywhx02bXmwETEXZ94XUaIBK_auwEXOwMgqmWCGPYbeyP70boylBNRL_59-hA0MGdFVXyqzqT-G_96G6QrkUR6YyOsL-hUkTpKgip4-2ZNSs2mEYIqZv-yvF0xryuVDElf/s320/Screen+Shot+2013-05-15+at+13.47.45.png" title="" width="146" /></a></div>
<div style="text-align: center;">
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: x-small;">Download<span style="font-size: x-small;">able leaflets on <span style="font-size: x-small;">the geology, wildlife and history of Troopers Hill are available <span style="font-size: x-small;">at <a href="http://www.troopers-hill.org.uk/leaflets/index.htm">http://www.troopers-hill.org.uk/leaflets/index.htm</a></span></span></span></span></span><b> </b><br />
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: x-small;"><span style="font-size: x-small;"><span style="font-size: x-small;"><br /></span></span></span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: x-small;"><span style="font-size: x-small;"><span style="font-size: x-small;"><br /></span></span></span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: xx-small;"><span style="font-size: xx-small;"><span style="color: red; font-size: x-large;">December 2016 Update.</span></span></span></span><br />
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: xx-small;"><span style="font-size: xx-small;"><span style="font-size: large;"><br /></span></span></span></span></div>
<div style="font-family: 'courier new', courier, monospace; text-align: left;">
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: xx-small;"><span style="font-size: xx-small;"><span style="font-size: large;">Eileen Stonebridge and Andrew Mathieson, of The Avon RIGS Group, have been working for some time with The Friends of Troopers Hill on the interpretation boards in general and the Geological interpretation board in particular. This new board can be seen near the Upper Chimney.</span></span></span></span><br />
<span style="font-family: "verdana" , sans-serif;"><span style="font-size: xx-small;"><span style="font-size: xx-small;"><span style="font-size: large;"><br /></span></span></span></span></div>
<div style="text-align: left;">
<span style="font-family: "verdana" , sans-serif; font-size: large;">The four boards can be seen on this page of the Troopers Hill web site:-</span></div>
<div style="text-align: left;">
<span style="font-family: "verdana" , sans-serif; font-size: x-small;"><br /></span></div>
<div style="text-align: left;">
<div style="text-align: center;">
<span style="background-color: white;"><span style="color: blue;"><a href="http://www.troopers-hill.org.uk/sundry/board.htm#geology">Troopers Hill Interpretation Boards</a></span></span></div>
</div>
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<span style="font-family: "verdana" , sans-serif;"><span style="font-size: x-small;"><span style="font-size: x-small;"><span style="font-size: x-small;"><br /></span></span></span></span></div>
</div>
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<b><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">References
</span></span></b></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">
</span></span><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">Anstie, 1873, The Coalfields of Gloucestershire and Somersetshire, London
</span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">
</span></span><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">Bristol Fireclay Company Co Ltd, 1911, Section of the Mines at Troopers Hill
</span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">
</span></span><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">British Geological Survey 6 inch map Sheet ST 67 SW
</span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">
</span></span><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">Buckland and Conybeare, 1824, Transactions of the Geological Society of London (available online
through Google Books)
</span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">
</span></span><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">Cornwell, 2003, The Bristol Coalfield, Landmark Publishing
</span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">
</span></span><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">Fry, Accounts of my Earliest Years (up to 1922) www.troopers-hill.org.uk/memories
</span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">
</span></span><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">Kellaway and Welch, 1993, Geology of the Bristol District, HMSO
</span></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">
</span></span><span style="font-size: x-small;"><span style="font-family: "verdana" , sans-serif;">Prestwich, 1871, Report of the Royal Commission on Coal (in) Gloucestershire and Somersetshire,
HMSO (available online through Google Books)
</span></span></div>
</div>
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<br /></div>
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<span style="font-size: x-small;"><i><span style="font-family: "verdana" , sans-serif;">
</span></i></span></div>
<div style="font-family: 'courier new', courier, monospace;">
<span style="font-size: x-small;"><i><span style="font-family: "verdana" , sans-serif;">The original walk was funded by our Stepping Forward Sustainability Grant, through the BIG Lottery Community
Spaces Programme <span style="color: blue;">www.troopers-hill.org.uk/steppingforward
</span></span></i></span></div>
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Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-56112612090086878172013-03-29T05:20:00.002-07:002013-03-31T02:17:00.088-07:00RIGS of the month [March] - Middle Hope<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="font-family: Verdana,sans-serif; text-align: center;">
<br />
<span style="font-size: x-large;"><b>RIGS of the Month - March</b></span><br />
<span style="font-size: x-large;"><b><span style="color: #0c343d;"><span style="font-size: x-large;">Middle Hope</span>, Kewstoke, Somerset </span></b></span></div>
<div style="text-align: center;">
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<div style="text-align: center;">
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjG0zJnWE8wufEfL9u4lFB-BQU1GN0bvEjjay1Zia3cIz_Ue5wwKbKnOewoHRr_AQl-zdgJ9n18dpWgpsMQG69FILwhQl9A8GZDta0lVF_JUBmnmZ59yXvqDNqlAe91Ad1n_KvCDnSnTaQz/s1600/Screen+Shot+2013-03-20+at+10.32.02.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="252" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjG0zJnWE8wufEfL9u4lFB-BQU1GN0bvEjjay1Zia3cIz_Ue5wwKbKnOewoHRr_AQl-zdgJ9n18dpWgpsMQG69FILwhQl9A8GZDta0lVF_JUBmnmZ59yXvqDNqlAe91Ad1n_KvCDnSnTaQz/s400/Screen+Shot+2013-03-20+at+10.32.02.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">Fig 1: <span style="font-size: x-small;">Locality map<span style="font-size: x-small;">. </span></span>Blue arrow shows location of RIGS on OS <span style="font-size: x-small;">m</span>ap (original scale = 1:25,000). </span></span></b></td></tr>
</tbody></table>
<div style="text-align: left;">
<span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><i>Directions: After parking at the end of Beach Road,
take the steps up to the top of the headland and keep right, away from
the trig point. Go through the kissing gate in the wall and immediately
turn left. Head down the bank and turn left again (heading east),
keeping parallel with the coastline. Proceed for ~300m until you read a
small pebbled beach.</i></span></span></div>
</div>
<div style="font-family: "Courier New",Courier,monospace; text-align: center;">
<br />
<span style="font-size: small;"><b>SITE SPECIFIC INFORMATION </b></span><br />
<div style="text-align: left;">
<span style="font-size: small;"><b>Location: </b></span><span style="font-size: small;"><span class="pp-headline-item pp-headline-address" dir="ltr">Roughly BS22 9UR</span> (GR = ST 324661<span style="font-size: small;">. Marked as <span style="font-size: small;">"Swallow Cliff<span style="font-size: small;">" on <span style="font-size: small;">1:50,000 OS Map<span style="font-size: small;">)</span></span></span></span></span><b> </b></span></div>
</div>
<div style="font-family: "Courier New",Courier,monospace;">
<span style="font-size: small;"><b>Accessibility:</b><span style="font-size: small;"> Car pa<span style="font-size: small;">r<span style="font-size: small;">k at the end of <span style="font-size: small;">Beach Road. Footpath with st<span style="font-size: small;">eep steps.</span></span></span></span></span></span></div>
</div>
<div style="font-family: "Courier New",Courier,monospace; text-align: left;">
<span style="font-size: small;"><b>Risks: </b><span style="font-size: small;">C<span style="font-size: small;">heck tides before heading down onto<span style="font-size: small;"> t<span style="font-size: small;">he b<span style="font-size: small;">each. Beware of falling rocks be<span style="font-size: small;">neath cliff <span style="font-size: small;">faces</span></span></span></span></span></span></span></span><br />
<span style="font-size: small;"><b>Topography:</b> Hilly,<span style="font-size: small;"> <span style="font-size: small;">gra<span style="font-size: small;">ssed foo<span style="font-size: small;">tpaths</span></span></span></span></span><br />
<span style="font-size: small;"><b>Restr<span style="font-size: small;">ictio<span style="font-size: small;">ns</span></span>:</b> The site is a<span style="font-size: small;"> designated a<span style="font-size: small;">s a</span></span> <a href="http://www.sssi.naturalengland.org.uk/Special/sssi/index.cfm">SSSI</a><span style="font-size: small;"><span style="font-size: small;"><span style="font-size: small;"><span style="font-size: small;"> so please do not hammer or sample from the <span style="font-size: small;">ex<span style="font-size: small;">posures</span></span></span></span></span></span></span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYZyFLV6rXtflb2qXHPHRVheBexoWB0ndtyDafpF7LZztIsJHeHo1CZMDf3fxsxpetL-3zKTl3s-21nVUxCzdvqS-kUyatvVJ3NZgnkyNJtK47oibDojB-NCD031oHKj_nxd42cr8s5-zd/s1600/middle+hope.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYZyFLV6rXtflb2qXHPHRVheBexoWB0ndtyDafpF7LZztIsJHeHo1CZMDf3fxsxpetL-3zKTl3s-21nVUxCzdvqS-kUyatvVJ3NZgnkyNJtK47oibDojB-NCD031oHKj_nxd42cr8s5-zd/s400/middle+hope.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><b>Fig. 2: View of exposures looking directly west from ST 32466. The oldest Black Rock Limestone unit <span style="font-size: x-small;">lies</span> to the north (out of the field of view <span style="font-size: x-small;">- </span>see fig. 3).</b></span></span></td></tr>
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<b>Introduction</b> <br />
The <a href="http://avonrigsoutcrop.blogspot.co.uk/p/geology-of-avon-region.html" target="_blank">geology of Avon</a> is dominated by sedimentary rocks, but the coastal exposure at Middle Hope offers the chance to see volcanic deposits intercalated with Carboniferous Limestone. The mix of sediments and volcanic deposits allows accurate reconstruction of the sequence of events that took place in this area some 350 million years ago (Ma). Ash layers within fossiliferous sediments record the onset of volcanic activity in a shallow sub-marine setting, before proceedings culminated in an extrusive pillow basalt (fig. 3). Such volcanism is typical of the early Carboniferous in the UK; most vents were small and short-lived, having only a localised impact on their surroundings.<br />
<br />
<b>Outcrop description</b><br />
The younging direction is roughly north-south. Carboniferous Limestone is gradually disturbed and then overwhelmed by volcanic deposits before reappearing at the top of the sequence. The entire succession has been tilted due to the huge compressive forces associated with formation of Pangea during the <a href="http://www.geolsoc.org.uk/en/Plate-Tectonics/Chap4-Plate-Tectonics-of-the-UK/Variscan-Orogeny">Variscan Orogeny</a> at the
end of the Carboniferous period.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmEZPUdGvRiyEjknHHWjdLkpW2-tDyyTpir4jp2S78OkeuU77uBO679ICPs3yRXK034MLpEBbq1JE46WEPIbPCPV9UtsUXsl4KytwxE_KOPhkInNtbPJ8xSesJanw67e8I41tG4w4RagVX/s1600/geologic+setting+middle+hope.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" height="244" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmEZPUdGvRiyEjknHHWjdLkpW2-tDyyTpir4jp2S78OkeuU77uBO679ICPs3yRXK034MLpEBbq1JE46WEPIbPCPV9UtsUXsl4KytwxE_KOPhkInNtbPJ8xSesJanw67e8I41tG4w4RagVX/s320/geologic+setting+middle+hope.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b>Fig.3: Schematic
representation of Middle Hope geological setting. Outcrop is located
below the storm wave base (SWB) on a carbonate platform. FWB =
Fair-weather wave base. After Faulkner (1989).</b></td></tr>
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<br />
<div style="text-align: center;">
<i><span style="font-size: x-small;">Unit name colours correspond to <span style="font-size: x-small;">labelling on fig.<span style="font-size: x-small;">2</span></span></span></i></div>
<br />
<span style="color: magenta;"><b>Limestone (pre-volcanic)</b></span><br />
The oldest unit at this exposure dates from the early Carboniferous (~355 Ma), and forms part of the Black Rock Limestone group. Bedded at roughly 20cm intervals, it is fine-grained and highly fossiliferous, containing abundant crinoid ossicles, brachiopods and corals<b> </b>fragments (fig.4). In places the sediments have been bioturbated by ancient burrowing organisms and yield a variety of trace fossils. The preservation of these delicate structures indicates these sediments were deposited in a low energy sub-marine environment, below the storm wave base of an offshore carbonate ramp (fig. 3).<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7db_7uk5F4KX0q9pzL5dNR01CfXrAwRsn8FWnInE2satvg12E68z3q7JdqgF-NmCF6PqF24HH1Tr9VGFvkO32VoA5LdBP0B8pBIxUCPD0elHZNunrOhApJ0EYynR0ejqzMZWTqFFvrbVA/s1600/limestone+1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7db_7uk5F4KX0q9pzL5dNR01CfXrAwRsn8FWnInE2satvg12E68z3q7JdqgF-NmCF6PqF24HH1Tr9VGFvkO32VoA5LdBP0B8pBIxUCPD0elHZNunrOhApJ0EYynR0ejqzMZWTqFFvrbVA/s400/limestone+1.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b>Fig. 4: The oldest limestone unit at Middle Hope dips 30º to the south and contains abundant fossils. Image on right shows close up of crinoid ossicles in long and cross section. </b></td></tr>
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<span style="color: magenta;"><b><span style="color: #38761d;">Interbedded tuffs and limestones </span> </b></span><br />
About 10m to the south, more tilted beds appear out of the shingle. This part of the outcrop consists of interbedded limestones and tuffs, the latter heralding the onset of volcanism in the area. In general, the grain size of the tuffs increases up-section, corresponding to increasing intensity of volcanic activity. The first beds are red in colour and are rich in bioclastic material. The alternating thin-bedded
limestones, some of which have ripples and cross-bedding, show that the volcanic outbursts were sporadic and of limited duration. Small lapilli-rich layers can be found in the tuff and conglomeritic deposits indicating there may have been pyroclastic currents or debris avalanches flowing down the carbonate ramp.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7rERNpD996YJwb7OkeCcmFy7NLl6o0rxfRY62xX1rY6_nLphPaq9pGMvrMWsfAJcnQ8MHBzOE7WnGV3NjKxx8bBsX62P9qANAC9j3ysUQtcC5EmSA9bJ8jemKDgfst6LZdUzvZsMKFUoz/s1600/bedded+tuff.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="191" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7rERNpD996YJwb7OkeCcmFy7NLl6o0rxfRY62xX1rY6_nLphPaq9pGMvrMWsfAJcnQ8MHBzOE7WnGV3NjKxx8bBsX62P9qANAC9j3ysUQtcC5EmSA9bJ8jemKDgfst6LZdUzvZsMKFUoz/s400/bedded+tuff.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b>Fig. <span style="font-size: x-small;">5</span>: </b></span><span style="font-size: x-small;"><b><span style="font-size: x-small;"><b><span style="font-size: x-small;">Image on left <span style="font-size: x-small;">shows </span></span>i</b></span>nterbedded limestone and tuff. <span style="font-size: x-small;">V<span style="font-size: x-small;">olcanic ac<span style="font-size: x-small;">t<span style="font-size: x-small;">ivity was im<span style="font-size: x-small;">persist<span style="font-size: x-small;">e</span>nt, allowing re<span style="font-size: x-small;">establ<span style="font-size: x-small;">ishment <span style="font-size: x-small;">of the carbonat<span style="font-size: x-small;">e <span style="font-size: x-small;">pla<span style="font-size: x-small;">tform in between eruptive epi<span style="font-size: x-small;">sodes.<span style="font-size: x-small;"> <span style="font-size: x-small;">Image on right <span style="font-size: x-small;">is a cong<span style="font-size: x-small;">lomeritic <span style="font-size: x-small;">sub-la<span style="font-size: x-small;">yer, p<span style="font-size: x-small;">ossibly <span style="font-size: x-small;">res<span style="font-size: x-small;">ulting f<span style="font-size: x-small;">rom pyroclastic or debris <span style="font-size: x-small;">flows.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span> </span></span></span></span></span></span></span> </span></b></span></td></tr>
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<b><span style="color: #660000;">Massive tuff (Middle Hope Volcanic Member)</span></b><br />
<span style="color: #660000;"><span style="color: black;">Above the bedded units lies the Middle Hope Volcanic Member. Greeny-black in appearance, this massive unit varies between 5-10m in thickness. Lapilli-rich zones appear in places and calcite veining associated with late Carboniferous tectonics is prominent. Near to the basal contact with the interbedded tuff there is evidence for metasomatism (chemical alteration by hydrothermal fluid); here, brown patches contain highly altered fossil fragments which have a distinctive green colouration.</span></span><br />
<span style="color: #660000;"><span style="color: black;"> </span></span><b><span style="color: #660000;"> </span></b><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8CJwAFg-wrUHV2qax9D_54ItVwmX6vEUGBBTrAy4KqVdjXu62WuvsZ6D6Xhpgf2VzRRe6GYw6bLVlGXSuz18r9ShdFs2GgvRFmyrrCP6QwlBGqkxUNXVmneJs1HvWdjsPIm8x3WuthkiS/s1600/tuff.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="151" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8CJwAFg-wrUHV2qax9D_54ItVwmX6vEUGBBTrAy4KqVdjXu62WuvsZ6D6Xhpgf2VzRRe6GYw6bLVlGXSuz18r9ShdFs2GgvRFmyrrCP6QwlBGqkxUNXVmneJs1HvWdjsPIm8x3WuthkiS/s400/tuff.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b>Fig. <span style="font-size: x-small;">4</span>: Middle Hope Volcanic Member. Massive<span style="font-size: x-small;"> green-black tuff de<span style="font-size: x-small;">posit with extensive ca<span style="font-size: x-small;">lcite veining. <span style="font-size: x-small;">Close up shows <span style="font-size: x-small;">metasomatise<span style="font-size: x-small;">d basal contact <span style="font-size: x-small;">with underlying limestone.</span></span></span></span></span></span></span> </b></span></td></tr>
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<b><span style="color: #b45f06;">Pillow basalt</span></b><br />
<span style="color: #b45f06;"><span style="color: black;">Immediately above the tuff is <span style="font-size: small;">a fine-grained </span>pillow basalt, the result of an extrusive sub-marine lava flow. It varies in thickness up to 4.5m and good pillow shapes can be made out towards the base. The upper surface of the basalt is full of voids (</span></span><span style="color: #b45f06;"><span style="color: black;"><span style="color: #b45f06;"><span style="color: black;">amygdales)</span></span> up to 10cm in diameter; when the lava was molten, these would have been filled with gas. Some have been stretched parallel to the flow direction of the lava. Later alteration has infilled the amygdales with calcite. </span></span><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqVHGxej4Gw1Etjktjzvvo7YbIPb6lpSf-B3HwlLXt0wy-kUAOoX3909TIfBNR_yrrcm-Ctde02130gdGtmCPHvfXJJFTiVg8HAUDE99qoBEpH5_As4F_k-irv6TSnIThjPTJmbRGSHq38/s1600/pillow+basalt.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="193" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqVHGxej4Gw1Etjktjzvvo7YbIPb6lpSf-B3HwlLXt0wy-kUAOoX3909TIfBNR_yrrcm-Ctde02130gdGtmCPHvfXJJFTiVg8HAUDE99qoBEpH5_As4F_k-irv6TSnIThjPTJmbRGSHq38/s400/pillow+basalt.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b>Fig<span style="font-size: x-small;">. <span style="font-size: x-small;">6</span></span>: Pillow basalt. Outcrop in left image is about 3m in height. Close up on left shows amygdales (voids left by gas bubbles) <span style="font-size: x-small;">elongated pa<span style="font-size: x-small;">rallel to flow <span style="font-size: x-small;">direction </span></span></span>which have been infilled later by calcite.</b></span><br />
<div style="text-align: left;">
<span style="font-size: x-small;"><b> <span style="font-size: small;"><span style="color: #0b5394;"> </span></span></b></span></div>
<div style="text-align: left;">
<span style="font-size: small;"><b><span style="color: #0b5394;">Limestone (post-volcanic)</span></b></span></div>
<div style="text-align: left;">
<span style="font-size: small;">After the extrusion of the basalt, the intensity of volcanic activity receded and is again recorded in gradually fining tuff layers interbedded with fossilerous limestone. The cliff deposits then grade into Black Rock Limestone, and finally Gully Oolite (which can also be found in the Avon Gorge). </span><br />
<span style="font-size: small;"><b><br /></b></span>
<br />
<span style="font-family: "Courier New",Courier,monospace; font-size: x-small;">Charly Stamper</span><b><br /></b></div>
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<span style="font-size: x-small;"><i><b>Quaternary geology</b></i></span><br />
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<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><i>The capping<span style="font-size: x-small;"> deposits on the cliff are a</span> Pleistocene aged fossil cliff and shore platform. The raised-beach deposits have been correlated with the last interglacial, and this is the only Pleistocene raised-beach site where such a sequence can be demonstrated and as such is of fundamental importance to quaternary geology.</i></span></span></div>
<span style="font-size: x-small;"><i><b> </b></i></span><i><b><span style="font-size: x-small;"> </span></b></i><br />
<i><b><span style="font-size: x-small;">Biological</span></b></i><br />
<i><span style="font-size: x-small;">Middle Hope is designated as an SSSI for both its geological and biological features<span style="font-size: x-small;">. The headland </span>supports a calcareous grassland community with a restricted British distribution<span style="font-size: x-small;"> <span style="font-size: x-small;">(</span></span></span><span style="font-size: x-small;">Festuca species and Dactylis glomerata).</span></i><br />
<br />
<b><span style="font-size: x-small;"><span style="font-size: x-small;">Referenc<span style="font-size: x-small;">es:</span></span></span></b><span style="font-size: x-small;"><span style="font-size: x-small;"><span style="font-size: x-small;"> </span></span></span><br />
<span style="font-size: x-small;"><span style="font-size: x-small;"><span style="font-size: x-small;">
</span></span></span><br />
<span style="font-family: 'Times'; font-size: 14.000000pt; font-weight: 700;"> </span><span style="font-family: 'Times'; font-size: 14pt;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;">- Faulkner<span style="font-size: x-small;"> TJ (1989) </span>The early Carboniferous (Courceyan) Middle Hope volcanics </span></span></span><span style="font-size: x-small;">of
Weston-super-Mare: development and demise of an
offshore volcanic hig<span style="font-size: x-small;">h.</span></span><span style="font-family: 'Times'; font-size: 8.000000pt; font-style: italic;"> </span><span style="font-family: 'Times'; font-size: 8pt;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;">Proc. Geol. Ass.,
</span></span></span><span style="font-size: x-small;">100(1), 93-106.</span><br />
<br />
<span style="font-size: x-small;"><span style="font-size: x-small;"><span style="font-size: x-small;"><span style="font-size: x-small;">- Volcanic rocks of the Bristol region<span style="font-size: x-small;"><span style="font-size: x-small;">,</span> S<span style="font-size: x-small;">peedyman DL. in </span></span>Geological excursions in the Bristol District. <span style="font-size: x-small;">Savage RJG (1977). <span style="font-size: x-small;">University of Bristol. </span></span> </span></span></span> </span></div>
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Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-65193890924440126402013-02-25T01:58:00.000-08:002013-02-25T02:02:24.622-08:00The Hot Well, Bristol<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="color: #134f5c;"><span style="font-size: large;"><span style="font-family: Verdana,sans-serif;"><b>The Hot Well spring, Bristol</b></span></span></span><br />
<span style="color: #134f5c;"><span style="font-size: large;"><span style="font-family: Verdana,sans-serif;"><i><span style="color: black;">From rags to riches and back aga<span style="font-size: large;">in - </span></span></i></span></span></span><br />
<span style="color: #134f5c;"><span style="font-size: large;"><span style="font-family: Verdana,sans-serif;"><i><span style="color: black;"><span style="font-size: large;">the s<span style="font-size: large;">tor<span style="font-size: large;">y of the Hotwe<span style="font-size: large;">lls spa</span></span></span></span></span></i></span></span></span><br />
<span style="color: #134f5c;"><span style="font-size: large;"><span style="font-family: Verdana,sans-serif;"><i><span style="color: black;"><span style="font-size: large;"><span style="font-size: large;"><span style="font-size: large;"><span style="font-size: large;"> </span></span></span></span></span></i></span></span></span><b> </b></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhL7wO1GqY4CsnsIMCzozGy8I3TKWYMsVYMqJtMGLfT2vV_luBeukJNhv-_f3uaIeps6t_loO4ibY1bkxg016GpjeMpODpt1hykTvALQve-y6BuRtVBjQqu8VXZw759v1pdAjPz6eCCwZBy/s1600/IMG_0378.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhL7wO1GqY4CsnsIMCzozGy8I3TKWYMsVYMqJtMGLfT2vV_luBeukJNhv-_f3uaIeps6t_loO4ibY1bkxg016GpjeMpODpt1hykTvALQve-y6BuRtVBjQqu8VXZw759v1pdAjPz6eCCwZBy/s320/IMG_0378.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b><span style="font-family: Verdana,sans-serif;">The old Hotwell House on the banks of the Avon. Built in 1696, it held a pump rooms and lodgings for visitors. After the terminal decline of the Hot Wells spa, i</span><span style="font-family: Verdana,sans-serif;">t was demolished in 1822<span style="font-size: x-small;"> and</span> no remnants of its former glories remain, the site being adjacent to The Portway.</span></b></span></td></tr>
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<span style="font-family: Verdana,sans-serif;"><b style="mso-bidi-font-weight: normal;"><span lang="EN-US">INTRODUCTION</span></b></span><br />
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</span><br />
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<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">The King’s Spring in Bath has been exploited
by humans since 836BC, most famously by the Romans who built the first baths,
and then later during the spa age of the 18<sup>th</sup> century. Less renowned
is the eponymous spring of Hotwells in Bristol. At its peak in the Georgian
era, the “Hot Well” served a fully functioning pump room and hot baths, and
provided the catalyst for much of the development in Clifton. Today, the spring
has diminished in flow and is only visible at low tide as a trickle emanating
from the banks of the River Avon.</span></span></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFY3j5pepGY5lDWFTxQKx4OUoY0gGBkabiC5iPVoRkEPrHTrhcJdV6kYGu8ncH8CdqLn-CxyR2T3pcLgvUS2R_7NZkiekAesbwm3bvqrymtCz4TukCVQXJS37WjZEf_j_TKbzwbIm2Zoi4/s1600/IMG_0362.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFY3j5pepGY5lDWFTxQKx4OUoY0gGBkabiC5iPVoRkEPrHTrhcJdV6kYGu8ncH8CdqLn-CxyR2T3pcLgvUS2R_7NZkiekAesbwm3bvqrymtCz4TukCVQXJS37WjZEf_j_TKbzwbIm2Zoi4/s400/IMG_0362.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;">The modern<span style="font-size: x-small;">-day </span>resurgence of the Hot Well from the banks of the Avon as visible at low tide. All photo credits: Charly Stamper </span></span></b></td></tr>
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<span style="font-family: Verdana,sans-serif;"><b style="mso-bidi-font-weight: normal;"><span lang="EN-US">HISTORICAL
BACKGROUND</span></b></span></div>
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<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">The spring was first mentioned in 15<sup>th</sup>
century historical records, and by the 1630s it was being regularly visited by
society. The thermal water emerged on both sides of the Avon, roughly opposite
the intersection the The Portway and Bridge Valley Road. It was contemporarily
described as being "milky white" and was thought to have restorative properties,
particularly for "hot livers, feeble brains and red pimply faces". During the
17<sup>th</sup> century the spring was relatively inaccessible, for there was no
formal path and a descent from Clifton involved “200 slippery steps”. </span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">As the popularity of spas increased in the
Georgian era, so did the number of visitors to Lower Clifton. Initially, development
focused on the area adjacent to the natural resurgence, with the building of a
spa (old Hotwell House), entertainment complexes (Jacob Wells theatre) and genteel housing (eg. Dowry Square). In the 18<sup>th</sup>
century the spring’s reputed curing powers extended to venereal disease,
tuberculosis and cancer.</span></span></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjABjRZRon-2yAq3LA0Njh66Va3ialZQfyngDSbFIhLg-pxEIpMDj0e_cL6HzhOrf5RtQI3z-HGZwxpmi56hl9sgm5sgFkywOtJfMR26UhYS4bIeneSZQYieRNmBWq7iS3ygejoh9wLzfmi/s1600/IMG_0371.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjABjRZRon-2yAq3LA0Njh66Va3ialZQfyngDSbFIhLg-pxEIpMDj0e_cL6HzhOrf5RtQI3z-HGZwxpmi56hl9sgm5sgFkywOtJfMR26UhYS4bIeneSZQYieRNmBWq7iS3ygejoh9wLzfmi/s320/IMG_0371.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><b>Strangers' Burial Ground, Lower Clifton Hil<span style="font-size: x-small;">l.<span style="font-size: x-small;"> <span style="font-size: x-small;">By th<span style="font-size: x-small;">e 1750s, </span>t</span>he Hot Well acquired a reputation for curing tuberc<span style="font-size: x-small;">ulosis; <span style="font-size: x-small;">however, these c<span style="font-size: x-small;">laims were unfounded and an <span style="font-size: x-small;">overflow burial ground w<span style="font-size: x-small;">as in<span style="font-size: x-small;">stat<span style="font-size: x-small;">ed to cater for<span style="font-size: x-small;"> unfortunate commoners <span style="font-size: x-small;">who came from ou<span style="font-size: x-small;">tside of the parish.</span></span></span></span></span></span></span></span></span></span></span></span></b></span></span></td></tr>
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<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">The main dent in the Hot Well's popularity remained
the distance and difficulty of access down the steep sides of the Avon Gorge, and in the mid 1780s Thomas Morgan embarked on an ambitious engineering project
to bring the waters to the heart of Clifton. From Sion Row he drilled a shaft some
250ft through the Carboniferous limestone to tap the hot waters, supplying
water to a new pump room with hot baths and a reading room, later to become
the St Vincent Rocks Hotel (now Avon Gorge Hotel). By 1793, this diversion had
become known as the “New Hot Well”.</span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">In the following years, both springs began
to cool, almost certainly as result of increased groundwater mixing. This
coincided with a nationwide decline in spa popularity in favour of sea bathing,
increase in subscription charges and end of the Napoleonic Wars, meaning
British people were free to travel abroad. Several revival attempts in the 19<sup>th</sup>
century failed to capture former glories, and the spring is no longer
commercially exploited. </span></span><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOUeC8nVay7SNfNZ_pfXofAlogu2vLoIz0o9rzsIWgviFMeeeTmQBGtQQins4olb5FwfNYjtYphkT4AmJH0F1iLHL0Dw00Cs4ilHNVhHzC1XrTnf10ZTDoIGka6S4tR-bfnOIRrVfeCheL/s1600/IMG_0360.JPG" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOUeC8nVay7SNfNZ_pfXofAlogu2vLoIz0o9rzsIWgviFMeeeTmQBGtQQins4olb5FwfNYjtYphkT4AmJH0F1iLHL0Dw00Cs4ilHNVhHzC1XrTnf10ZTDoIGka6S4tR-bfnOIRrVfeCheL/s320/IMG_0360.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><b>The Colonnad<span style="font-size: x-small;">e, Hotwells Road. Originally </span></b></span><span style="font-family: Verdana,sans-serif;"><b><b>a shopping arcade</b>, it was built in 1786 as an</b></span></span><b><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"> attempt at reviving the failing fortunes of the Hot Wells spa</span></span>.</b></td></tr>
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<span style="font-family: Verdana,sans-serif;"><b style="mso-bidi-font-weight: normal;"><span lang="EN-US">GEOCHEMISTRY
AND HYDROGEOLOGY</span></b></span>
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<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">Modern day studies of the hot springs of
the Avon area have tried to shed some light on the source and science behind
their existence. In 1993, the yield of the Hot Well was measured at 0.41 x 10^6
litres a day, about a third of the present-day flow recorded at the
King’s Spring in Bath and enough to fill an Olympic-sized swimming pool in a
week. Compositionally, the two springs are very similar, being rich in calcium
and sulphates, though 25% of the Hot Well volume is cold groundwater,
reflected in the relatively low average temperature of 24ºC.</span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">The source of the two springs is thought to
be rainfall in the Mendip Hills, some 15km to the south-west. <span style="mso-spacerun: yes;"> </span>Measured carbon isotopes (∂<sup>13</sup>C)
are consistent with storage in Carboniferous Limestone, and hydrogen and oxygen
isotopes provide evidence that most of the water is <a href="http://en.wikipedia.org/wiki/Meteoric_water" target="_blank">meteoric</a> in origin. The head
at this elevated topography is high enough to force the water down beneath the
Coal Measures to a depth of around 2.7km in the Bristol-Bath basin and heat
the groundwater; silica geothermometers indicate the thermal component of the
springs reaches a maximum temperature of 72ºC. </span></span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDSvVlA39XuJJLDLiqTzpRIT9GpRHKJsqCF8DVs-3LksVvvTtPhnCJoFfnibxjxL1gr62NZv1tb6Xm6d1S_6ztZ_RFfqLoScA_YJAcL-TYw58-Us35hs4GjEo-oxxGgJg_-AlO9VkHZgTY/s1600/cross+section.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDSvVlA39XuJJLDLiqTzpRIT9GpRHKJsqCF8DVs-3LksVvvTtPhnCJoFfnibxjxL1gr62NZv1tb6Xm6d1S_6ztZ_RFfqLoScA_YJAcL-TYw58-Us35hs4GjEo-oxxGgJg_-AlO9VkHZgTY/s400/cross+section.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Verdana,sans-serif;"><b><span style="font-size: x-small;">Cross section showing flow of groundwater through Carboniferous Limestone from source in the Mendip Hills to resurgence in Bath and Hotwells (Andrews et al., 1982).</span></b></span></td></tr>
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</div>
<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">The overlying stratum of the Coal Measures
is a proven <a href="http://or.water.usgs.gov/projs_dir/willgw/glossary.html" target="_blank">aquiclude</a>, so no upward migration can take place. The area north of
the Mendips is heavily faulted and folded from both Mesozoic and Tertiary
tectonics, so the water migration is unlikely to be direct. Tritium (<sup>3</sup>H)
was produced by thermonuclear weapons testing in the 1950s and is used to
identify any modern-day recharge in groundwater. Low tritium levels in the Hot
Wells indicate only minor amount of mixing with of ‘recent’ waters, and the
majority is likely to be up to 10,000 years old. At the end of its journey, the
Hot Well resurges directly from Carboniferous Limestone into the channel of the
Avon river.</span></span><br />
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<span style="font-family: Verdana,sans-serif;"><b style="mso-bidi-font-weight: normal;"><span lang="EN-US">THE
FUTURE</span></b></span></div>
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</span><br />
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<span style="font-family: Verdana,sans-serif;"><span lang="EN-US">Although the Hot Well spring has had its </span></span><span style="font-family: Verdana,sans-serif;"><span lang="EN-US"><span style="font-family: Verdana,sans-serif;"><span lang="EN-US">heyday</span></span>, the King’s Spring at Bath remains at the heart of the city’s tourist trade.
In 2011, two companies (Eden Energy and UK Methane Ltd) were given licenses by
Mendip district council to begin a feasibility study for the controversial
practice known as “fracking”. Concerns were immediately raised by </span><span lang="EN-US" style="mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">councilors </span><span lang="EN-US">in Bath and led to a subsequent
uproar in the <a href="http://www.thisisbath.co.uk/New-fears-Bath-s-hot-springs-David-Cameron-backs/story-17638422-detail/story.html#axzz2LFywPccq" target="_blank">local</a> (<a href="http://www.guardian.co.uk/environment/2011/sep/28/shale-gas-threaten-bath-springs" target="_blank">and further afield</a>) media. A specially commissioned
British Geological Survey report concluded that the risk to the Bath springs
was no higher than any other part of the UK, although critics point out that
relatively little is still known about the subterranean flow of the groundwater. The energy companies are a long way off
obtaining the planning permission needed to begin exploratory drilling, but the
authorities would to well to bear in mind the role that human intervention had
in the decline of the Hot Well spring.</span></span><br />
<br />
<span style="font-family: Verdana,sans-serif;"><span lang="EN-US"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">Charly Stamper</span></span> </span></span></div>
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<span style="font-family: Verdana,sans-serif;"><b style="mso-bidi-font-weight: normal;"><span lang="EN-US">REFERENCES
AND FURTHER READING</span></b></span></div>
<span style="font-family: Verdana,sans-serif;">
</span><br />
<div class="MsoNormal">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><span lang="EN-US">Andrews JN, Burgess WG, Edmunds WM, Kay RLF
& Lee DJ (1982) The thermal springs of Bath. Nature 298: 339-343.</span></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
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<span style="font-size: x-small;"><br /></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
<div class="MsoNormal">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><span lang="EN-US">Atkinson TC & Davison RM (2002) Is the
water still hot? Sustainability and the thermal springs at Bath, England.
Geological Society, London, Special Publications, 193: 15-40.</span></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
<div class="MsoNormal">
<br />
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><span lang="EN-US">Clifton and
Hotwells Conservation Area
Character Appraisal (2010) Bristol City Council
http://www.bristol.gov.uk/sites/default/files/assets/documents/clifton-and-hotwells-character-appraisal.pdf</span></span><br />
<span style="font-size: x-small;"><br /></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
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<span style="font-family: Verdana,sans-serif; font-size: x-small;"><span lang="EN-US">Gallois RW (2007) The formation of the hot
springs at Bath Spa, U.K. Geol. Mag. Vol. 144, 741-747</span></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
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<span style="font-size: x-small;"><br /></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
<div class="MsoNormal">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><span lang="EN-US">Jones, D <span style="font-size: x-small;">(1992)</span> <i>History of Clifton. </i>Phillimore<i>.</i></span></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
<div class="MsoNormal">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><span lang="EN-US">Kellaway, GA (1993) The hot springs of
Bristol and Bath. Proceedings of the Ussher Society, 8, 83-88.</span></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
<div class="MsoNormal">
<span style="font-size: x-small;"><br /></span></div>
<span style="font-family: Verdana,sans-serif; font-size: x-small;"></span><span style="font-weight: normal;"><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><span id="btAsinTitle">Mow<span style="font-size: x-small;">l, T (1991) </span><i>To Build the Second City: Architects and Craftsmen of Georgian Bristol.<span style="font-size: x-small;"> </span></i></span></span></span></span><span style="font-weight: normal;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;">Redcliffe Press Ltd.</span></span></span><br />
<br />
<span style="font-family: Verdana,sans-serif; font-size: x-small;">
</span><br />
<div class="MsoNormal">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><span lang="EN-US">Smith NJP & Darling WG (2012) Potential
problems within the Bath and North East Somerset Council and surrounding area
with respect to hydrocarbon and other exploration and production. British
Geological Survey Commissioned Report CR/12/055, 26 pp.</span></span></div>
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Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-3978721426489298938.post-3451566570790446572013-02-18T05:31:00.003-08:002013-02-18T05:31:43.100-08:00Baryte (BaSO4)<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: center;">
<span style="color: #134f5c;"><b><span style="font-family: "Verdana","sans-serif"; font-size: 18.0pt;"><span style="color: black;">Minerals of the Avon region</span><o:p></o:p></span></b></span></div>
<div class="MsoNormalCxSpMiddle" style="text-align: center;">
<span style="color: #134f5c;"></span><b><span style="font-family: "Verdana","sans-serif"; font-size: 18.0pt;"><span style="color: #134f5c;">Baryte (Barium
Sulphate – BaSO<sub>4</sub>)</span><o:p></o:p></span></b></div>
<div align="center" class="MsoNormalCxSpMiddle" style="text-align: center;">
<br /></div>
<div class="MsoNormalCxSpMiddle">
<br /></div>
<div class="MsoNormalCxSpMiddle">
<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Colour:</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"><span style="font-size: x-small;"><b> </b></span>White
but is often coloured by other minerals to a pink or pale brown<o:p></o:p></span></div>
<div class="MsoNormalCxSpMiddle">
<br /></div>
<div class="MsoNormalCxSpMiddle">
<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Polymorphism:</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"><b> </b>Forms a series with Selestine<o:p></o:p></span></div>
<div class="MsoNormalCxSpMiddle">
<br /></div>
<div class="MsoNormalCxSpMiddle">
<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Name:</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"> From the Greek for <i>weight</i> due to it’s high specific <span style="color: #134f5c;"><b></b></span>gravity <o:p></o:p></span></div>
<div class="MsoNormalCxSpMiddle">
<br /></div>
<div class="MsoNormalCxSpMiddle">
<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Crystal
system:</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"> Orthorhombic with up to 70 forms<o:p></o:p></span></div>
<div class="MsoNormalCxSpMiddle">
<br /></div>
<div class="MsoNormalCxSpMiddle">
<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Specific
gravity</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">: 4.5 measured (</span><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">4.47 calculated)</span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"> <o:p></o:p></span></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Hardness:</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"> 2.5 – 3.5<o:p></o:p></span></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Group:</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"> Barite Group<o:p></o:p></span></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Association:</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"> Fluorite, calcite, dolomite,
rhodochrosite, gypsum, sphalerite, galena, stibnite.<o:p></o:p></span></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Occurrence:</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;"> A gangue mineral in low-temperature hydrothermal veins; in residual deposits<o:p></o:p> from
weathered barite-bearing limestones.<o:p></o:p></span></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">Local location</span></b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 13.5pt;">: Stancombe Quarry</span><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">, Flax Bourton</span><span class="apple-converted-space"><span style="font-family: Verdana, sans-serif; font-size: 9pt;"> </span></span><span class="apple-converted-space"><span style="font-family: Verdana, sans-serif;">(Working limestone quarry)<o:p></o:p></span></span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8i6P6WowE5x4FmnsDYBRcUeZPLrpXBXprhrAWkJ3bWbKUSyQIx67dnkefFeovowwncT5kbvlfEMqSqoTlxIC740I2hLt7ONStxeAZ_QC6Olq8UO9WNzrMdg-uTV-PPlnSRZhBnnMlqBRv/s1600/DSC07725.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8i6P6WowE5x4FmnsDYBRcUeZPLrpXBXprhrAWkJ3bWbKUSyQIx67dnkefFeovowwncT5kbvlfEMqSqoTlxIC740I2hLt7ONStxeAZ_QC6Olq8UO9WNzrMdg-uTV-PPlnSRZhBnnMlqBRv/s400/DSC07725.JPG" width="400" /></a></td></tr>
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><span style="font-size: x-small;"><b>Cross section of Baryte vein -Stancombe Quarry</b></span></span></div>
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><span style="font-size: x-small;">Picture credits Richard Kefford</span></span></div>
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><span style="font-size: x-small;">Larger pictures can be seen <a href="https://plus.google.com/photos/116847800033838242899/albums/5846250995830362961?banner=pwa">here</a></span></span></div>
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><span style="font-size: x-small;"><br /></span></span></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">Paragenesis
#1 - Bilbao supergene type<o:p></o:p></span></b></div>
<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">During the Late Triassic, iron rich
saline oxidising water leached through the rift basins formed during the early
Permian (~290 Ma) to the late Jurassic (~150 Ma).<o:p></o:p></span><br />
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">Paragenesis
#2 - Mississippi Valley Type ( MVT )<o:p></o:p></span></b></div>
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">In the Mendip
– Bristol<sub> </sub>vein field, baryte has been deposited by hydrothermal fluids in
tension cracks and fissures in the Carboniferous Limestone. The primary
minerals in these fissures are Galena and Sphalerite. <a href="http://en.wikipedia.org/wiki/Gangue">Gangue</a> minerals such as
Baryte and Calcite occur in banded formations where the veins pinch out. This
is known as the Mississippi Valley Type (MVT) and took place during the
Middle Jurassic (~170Ma).<sub> </sub><o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWaz17LHV1Glk959ABj8d7qNv2ncOQI7kotwO1FG_DeqpXYXEpJwZ35e9y0ejiVUS2BvCBd1qSt0f8Apet26FsJwxwXO1Zehw0_8LsTPCB6-et_kcqXZrR7uhhw7A2-YvI8A8nT5KbCjG7/s1600/DSC07726.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWaz17LHV1Glk959ABj8d7qNv2ncOQI7kotwO1FG_DeqpXYXEpJwZ35e9y0ejiVUS2BvCBd1qSt0f8Apet26FsJwxwXO1Zehw0_8LsTPCB6-et_kcqXZrR7uhhw7A2-YvI8A8nT5KbCjG7/s400/DSC07726.JPG" width="400" /></a></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><span style="font-size: x-small;">Baryte with associated galena and calcite - Stancombe Quarry</span></span></b></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><br /></span></b></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">Uses:</span></b></div>
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">By far the
greatest use of this mineral ~80%, is for the production of drilling mud for
use in oil exploration. The main reason for this is that it is very heavy and so helps to prevent blow
outs in the drilling stage of the exploitation of an oil reservoir. It is also
chemically inert. The specification for drilling mud includes a requirement
that the specific gravity should be 4.2 or greater.<o:p></o:p></span></div>
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">Non drilling
applications of barytes are comparatively small, although still important
because of their higher value. High purity grades of barytes with fine and
controlled particles sizes are used as fillers in marine and industrial paints,
in brake lining/ friction materials and in plastics. A specialised use of
barytes based on its high density and ability to absorb radiation, is as an
aggregate in dense concrete for shielding applications in the nuclear industry
and hospital radiation departments.</span><br />
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"></span><br />
<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><o:p></o:p></span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSlbwlFZNteFcEwDNF7SVDIus40ma7YhjQlAQm4Qob3QL0K-C-sKxO00Y4PHhYBe4nkdKFkctZmiEF13A2FJQJjid6oMYYiTmwH7S2JLJSFACbu-SSy199hwEoMVnx4_Hm5noqs1sBOzYo/s1600/DSC07632.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSlbwlFZNteFcEwDNF7SVDIus40ma7YhjQlAQm4Qob3QL0K-C-sKxO00Y4PHhYBe4nkdKFkctZmiEF13A2FJQJjid6oMYYiTmwH7S2JLJSFACbu-SSy199hwEoMVnx4_Hm5noqs1sBOzYo/s400/DSC07632.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><span style="font-size: x-small;"><b><span style="font-size: x-small;">B</span>laded rosettes of Baryte on associated red ochre</b></span></span><div class="MsoNormalCxSpMiddle" style="text-align: center;">
<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><span style="font-size: x-small;">Sample found by Leon Sparrow at Winford</span></span></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">Sources:<o:p></o:p></span></b></div>
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<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">Barytes is produced in England and Scotland. In England
it is now only produced as a by product of fluorspar mining and processing. In
Scotland, barytes is extracted as the sole mineral from the Foss Mine near
Aberfeldy. </span><br />
<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"></span><br />
<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"></span><br />
<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><o:p><br /></o:p></span>
<span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;"><o:p><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">Richard Kefford</span></span></o:p></span></div>
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<b><span style="font-family: "Verdana","sans-serif"; mso-bidi-font-size: 12.0pt;">References:<o:p></o:p></span></b></div>
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<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><span style="background-color: white; color: #17365d;"><a href="http://www.bgs.ac.uk/downloads/start.cfm?id=1349">www.bgs.ac.<b>uk</b>/downloads/start.cfm?id=1349</a> </span></span></span></div>
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<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><br /></span></span></div>
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<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><a href="http://www.aditnow.co.uk/documents/Bridford-Baryte-Mine/BARYTES-MINE.pdf">http://www.aditnow.co.uk/documents/Bridford-Baryte-Mine/BARYTES-MINE.pdf</a><o:p></o:p></span></span></div>
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<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><br /></span></span></div>
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<span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">Chidlaw, N. (2012) Metamorphism and Mineralisation in the Bristol - Mendip area</span></span></div>
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-69949413459839790082013-02-05T05:49:00.003-08:002013-02-07T03:57:31.380-08:00Geo-gardening at Trendlewood Quarry, Nailsea<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="color: #134f5c;"><span style="font-size: large;"><b><span style="font-family: Verdana,sans-serif;"><br /></span></b></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="color: #134f5c;"><span style="font-size: large;"><b>Geo-gardening - Sunday 3rd February 2013</b></span></span></span></div>
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<span style="font-family: Verdana,sans-serif; font-size: small;"><span style="line-height: 115%;">On Sunday 3<sup>rd</sup> February 2013 a Joint Gardening Force (JGF) from Friends
of Trendlewood Park (FoTP) and Avon RIGS Group descended on Trendlewood Quarry in
Nailsea and proceeded to spend a few hours clearing ivy and other encroaching
vegetation from the lower parts of the quarry face in three areas.</span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: 14.0pt; line-height: 115%; mso-ascii-theme-font: minor-latin; mso-bidi-font-size: 11.0pt; mso-hansi-theme-font: minor-latin;"></span></span><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGGL31EdJkbsX9NJGxLhMI4uaZ3VVnFMhlYaMZLqDjol6P4RttVixCINHPdBJCKb_2lq179ZpSSi4Mkici9wH0zbIJqJlSrEfp_FC0j-qjdvcJ-vxVIrmUxxh4GnxlhlfnxO2PAIDkNJjH/s1600/DSC07710.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGGL31EdJkbsX9NJGxLhMI4uaZ3VVnFMhlYaMZLqDjol6P4RttVixCINHPdBJCKb_2lq179ZpSSi4Mkici9wH0zbIJqJlSrEfp_FC0j-qjdvcJ-vxVIrmUxxh4GnxlhlfnxO2PAIDkNJjH/s400/DSC07710.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;">Before worked started. Photo credits: Richard Kefford. More photos at </span></span></b><br />
<div style="text-align: center;">
<b><span style="font-family: Verdana,sans-serif;"><span style="background-color: white; color: #222222; font-size: x-small; line-height: normal; text-align: left;"><a href="http://tinyurl.com/bwd6shw" style="color: #1155cc;" target="_blank">http://tinyurl.com/<wbr></wbr>bwd6shw</a></span></span></b></div>
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<span style="font-family: Verdana,sans-serif; font-size: small;"><span style="line-height: 115%;">These three areas were selected to
demonstrate the differing bedding types – from varves to massive - in this Pennant Sandstone of the Downend
Formation and the differing types of deposition – point bars and channel deposits.</span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="font-size: 14.0pt; line-height: 115%; mso-ascii-theme-font: minor-latin; mso-bidi-font-size: 11.0pt; mso-hansi-theme-font: minor-latin;"><br /></span></span>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGniV4fnjNgBgl5tjbbj0Khk7He_PSVun9Wx7pC5GFVMxg48xwFHuOQE4XrpCO38_cWCRiYbYTBu8Ib99JGn-fdJra3LgRMNht-zy3TU4yr-DaeFKVKAV2gYbpRNbx6cF1GxzaIhS-dKEG/s1600/DSC07713.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGniV4fnjNgBgl5tjbbj0Khk7He_PSVun9Wx7pC5GFVMxg48xwFHuOQE4XrpCO38_cWCRiYbYTBu8Ib99JGn-fdJra3LgRMNht-zy3TU4yr-DaeFKVKAV2gYbpRNbx6cF1GxzaIhS-dKEG/s400/DSC07713.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><b>Geo-gardeners at work</b></span></span></td></tr>
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<br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: 14.0pt; line-height: 115%; mso-ascii-theme-font: minor-latin; mso-bidi-font-size: 11.0pt; mso-hansi-theme-font: minor-latin;"><span style="font-size: small;">This is the first part of the implementation
of the quarry management plan that was agreed at a site meeting between N
Somerset Council, Friends of Trendlewood Park and Avon RIGS Group. The second
part which will be carried out by the N Somerset Green Team will consist of
clearing the upper levels of the face and removing a few selected trees that
are in danger of falling and have extended their roots into the joints and
fissures rock close to the face and so are damaging the exposure.</span><o:p></o:p></span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: 14.0pt; line-height: 115%; mso-ascii-theme-font: minor-latin; mso-bidi-font-size: 11.0pt; mso-hansi-theme-font: minor-latin;"><br /></span></span>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuuz1XyAtMAwpPRsfG1_Fu0nZ5-hI5TJhknx8yFAfD9tk4VLePLmGiSuDoJihs6RjYpTxtsZ1AAIwnJt8HLpI35bmN2zf_yobre6yr9BwItOgXVY-XsF9pmVlgbu48joTDVvH-3rOvKs5b/s1600/DSC07712.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuuz1XyAtMAwpPRsfG1_Fu0nZ5-hI5TJhknx8yFAfD9tk4VLePLmGiSuDoJihs6RjYpTxtsZ1AAIwnJt8HLpI35bmN2zf_yobre6yr9BwItOgXVY-XsF9pmVlgbu48joTDVvH-3rOvKs5b/s400/DSC07712.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><b>Meeting one of the site natives</b></span></span></td></tr>
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<span style="font-size: small;"><br /></span>
<br />
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<span style="font-family: Verdana,sans-serif;"><span style="font-size: 14pt; line-height: 21px;"><span style="font-size: small;">See <a href="http://avonrigsoutcrop.blogspot.co.uk/2013/01/trendlewood-quarry-nailsea.html">here</a> for details of the geology of this site and its location.</span><o:p></o:p></span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="font-size: 14pt; line-height: 21px;"><br /></span></span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFiAB9Xq5jxMuhMrpo4A4uxLU-zkh9vjKDUTj1X8BqymV-dKYTBPjrzs1lgaUCCBS4lRs8l1vAIlJsPBrLfhRQObS3bF-MO4lonBRm-9s7H6HwKlIykZaazAiW0PD3s1AKcI5TSN-OWD_E/s1600/DSC07715.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFiAB9Xq5jxMuhMrpo4A4uxLU-zkh9vjKDUTj1X8BqymV-dKYTBPjrzs1lgaUCCBS4lRs8l1vAIlJsPBrLfhRQObS3bF-MO4lonBRm-9s7H6HwKlIykZaazAiW0PD3s1AKcI5TSN-OWD_E/s400/DSC07715.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;"><b>A cleared area on one face</b></span></span></td></tr>
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<span style="font-family: "Courier New",Courier,monospace;">Richard Kefford</span><br />
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-90999619775447533212013-02-04T15:11:00.000-08:002013-02-04T15:18:28.149-08:00Earth Heritage magazine<div dir="ltr" style="text-align: left;" trbidi="on">
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<b><span style="color: #134f5c;"><span style="font-family: Verdana,sans-serif;"><span style="font-size: large;">Earth Heritage magazine - free download</span></span></span></b></div>
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<span style="font-family: Verdana,sans-serif;">Earth Heritage is a magazine produced twice yearly to stimulate interest
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Heritage, Countryside Council for Wales and the Geologists' Association. </span><br />
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<b><span style="font-family: Verdana,sans-serif;">You can download the latest issue for free <a href="http://www.earthheritage.org.uk/ehpdf/EH39_01-13F.pdf">here</a>. </span></b><br />
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Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-41417782128786845662013-01-24T01:02:00.000-08:002013-08-20T07:13:01.684-07:00Trendlewood Quarry Nailsea<div dir="ltr" style="text-align: left;" trbidi="on">
<a href="http://www.blogger.com/blogger.g?blogID=3978721426489298938" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><span style="font-family: Verdana,sans-serif;"><br /></span>
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<span style="font-family: Verdana,sans-serif;"><b><span style="font-size: 18.0pt; mso-bidi-font-size: 11.0pt;">RIGS of the Month – January 2013<o:p></o:p></span></b></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="font-size: 18.0pt; mso-bidi-font-size: 11.0pt;"><span style="color: #0c343d;"><i>Trendlewood Quarry, Nailsea</i></span><o:p></o:p></span></b></span></div>
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id="_x0000_t75" coordsize="21600,21600" o:spt="75" o:preferrelative="t"
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height:312pt'>
<v:imagedata src="file:///C:\Users\Kefford\AppData\Local\Temp\msohtmlclip1\01\clip_image001.jpg"
o:title="DSC04784"/>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUd1Wlle4WAyjRhsY3Rni11OapnVZhLByAwY-1omQFwfMahBb234xopO9dTKdQmsIKE3wY6Ec8Id6O8sVKjjd4MGMSFwzWITa5BLo_IpwnLRr5vY9xnRdQm6RtV_sXTjVFBhDxhFRMaA21/s1600/DSC04784.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUd1Wlle4WAyjRhsY3Rni11OapnVZhLByAwY-1omQFwfMahBb234xopO9dTKdQmsIKE3wY6Ec8Id6O8sVKjjd4MGMSFwzWITa5BLo_IpwnLRr5vY9xnRdQm6RtV_sXTjVFBhDxhFRMaA21/s400/DSC04784.JPG" width="400" /></a></div>
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<span style="font-family: Verdana,sans-serif;"><span style="mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><span style="font-size: x-small;"><b>Pennant Sandstone quarry face in
Nowhere Wood</b></span><o:p></o:p></span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><span style="font-size: x-small;">( Double click on picture for larger view )</span></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">More photos at </span><b><span style="background-color: white; background-position: initial initial; background-repeat: initial initial; font-size: 10pt;"><a href="http://tinyurl.com/b7k53sy">http://tinyurl.com/b7k53sy</a> </span></b><span style="background-color: white; font-size: 8pt;">Photo credits Richard Kefford</span><b><span style="background-color: white; background-position: initial initial; background-repeat: initial initial; font-size: 10pt;"><o:p></o:p></span></b></span></div>
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<span style="font-family: Verdana,sans-serif;"></span><br />
<span style="font-family: Verdana,sans-serif;"></span></div>
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<span style="font-family: Verdana,sans-serif;"></span><br />
<span style="font-family: Verdana,sans-serif;"></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Location</span></b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">: Trendlewood
Park, Nailsea ST 479 702<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"></span><br />
<span style="font-family: Verdana,sans-serif;"></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">RIGS citation: </span></b></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">‘</span></b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Best
surviving exposure of Carboniferous Pennant Sandstone in the Nailsea Coalfield.’<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"> </span></b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">It is designated
as a RIGS because of its aesthetic and education value<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><br /></span></div>
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<span style="font-family: Verdana,sans-serif;"><br /></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Access: </span></b></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Head
North<b> </b>from Nailsea and Backwell
railway station, passing St
Francis school on the right. Turn right along a public footpath just after the
crescent to enter Tendlewood Park. Follow the path
through the wood then take a path to the right that slopes down on to the
quarry floor. Follow
the path until the quarry faces can be seen ahead and to the right.
Some parking is available in the crescent road.<o:p></o:p></span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><br /></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Risks:</span></b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"> </span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Keep
away from steep rock faces with loose material that can result
in rock falls. Hard hats should be worn when approaching the face.<o:p></o:p></span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><br /></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Topography:</span></b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"> </span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Path
through woodland, unstable rock faces.<o:p></o:p></span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><br /></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">General description:<o:p></o:p></span></b></span></div>
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<span class="Apple-style-span" style="font-family: Verdana, sans-serif;">This
is a disused quarry that was used to supply building stone to the local area.
It was in use until 1930.</span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span>
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">It
is located in Nowhere Wood which is part of Trendlewood Park. This park is
owned by North Somerset Council and managed jointly by the owners and a local
group of volunteers known as Friends of Trendlewood Park.<o:p></o:p></span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<a href="http://www.friendsoftrendlewoodpark.org.uk/">http://www.friendsoftrendlewoodpark.org.uk</a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9Ox9h2V88uDxBK01Pnb_6SzAGDvN4TDJabnAuJUJypbNOwASf6bmRlZC8kDowUMrZIaJKv27WDWcnZT8LcJB-_HlNU4aOhIbFeLNX9Fmk4GOZrnTcPMFmgR_iTPNOdrHBWaGD1Y1H6Lgf/s1600/DSC07688.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9Ox9h2V88uDxBK01Pnb_6SzAGDvN4TDJabnAuJUJypbNOwASf6bmRlZC8kDowUMrZIaJKv27WDWcnZT8LcJB-_HlNU4aOhIbFeLNX9Fmk4GOZrnTcPMFmgR_iTPNOdrHBWaGD1Y1H6Lgf/s400/DSC07688.JPG" width="400" /></a></div>
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<span style="font-family: Verdana,sans-serif;"><br /></span>
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><b>Entrance to Trendlewood Community Park</b></span><br />
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><b><br /></b></span></div>
</div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Geological history<o:p></o:p></span></b></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">The
closure of the Rheic Ocean by the end of the Carboniferous Period (~300 million years ago) caused the Variscan
Orogeny, resulting in folding of the strata in our area when ‘Nailsea’ was
just north of the equator. This produced high mountains which were then quickly
eroded, with the detrital material transported north to be laid down as Pennant
Sandstone in deltaic environments.<o:p></o:p></span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKccmTq_i5BeKZZKYpkxP4QQggM68MpFjFRhV4gGuddUOLRUWKSFqZGvGLaxQ_oGBiLvbOlTBIVWB1NQ8hXidfFCYPbR2s3kQTx9jw6FoGK6eGYgU11242xB3Yw3cB78L3zLZQIuxsWneT/s1600/ChronostratChart2012.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="282" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKccmTq_i5BeKZZKYpkxP4QQggM68MpFjFRhV4gGuddUOLRUWKSFqZGvGLaxQ_oGBiLvbOlTBIVWB1NQ8hXidfFCYPbR2s3kQTx9jw6FoGK6eGYgU11242xB3Yw3cB78L3zLZQIuxsWneT/s400/ChronostratChart2012.jpg" width="400" /></a></div>
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<b>Geological chronostratigraphic chart</b></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><br /></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Geological context<o:p></o:p></span></b></span></div>
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<span class="Apple-style-span" style="font-family: Verdana, sans-serif;">The
quarry is cut into Pennant Sandstone, a lithology that was deposited in a river system with point bar and channel deposits. The cross bedding directions
show that the provenance of the material was from the SSE. The rivers carried
eroded material from high ground that was upthrust during the Variscan Orogeny
that occurred during the late Carboniferous period.</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh93nS7VVUJfhyphenhyphen23bc7qmKFzBMdlZbI3QfA_bSQ3TOW65eQtcM_qCV9N5cU0f7CCJQ7t9t_Fy-hzENTs2FFlCxYScqM-N9xnvFFSPREA41ZIhn-jd4zoKdVFa-N0Dom4Qxzm9wwYkr0zlPq/s1600/cross_bed_formation.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="190" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh93nS7VVUJfhyphenhyphen23bc7qmKFzBMdlZbI3QfA_bSQ3TOW65eQtcM_qCV9N5cU0f7CCJQ7t9t_Fy-hzENTs2FFlCxYScqM-N9xnvFFSPREA41ZIhn-jd4zoKdVFa-N0Dom4Qxzm9wwYkr0zlPq/s400/cross_bed_formation.jpg" width="400" /></a></div>
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<span class="Apple-style-span" style="font-family: Verdana, sans-serif; font-size: x-small;"><b>Formation of cross bedding dune structures</b></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span>
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">The
Sandstone is part of the Downend Formation which is up to 660m thick in the
Somerset Coalfield. It consists mainly of sandstone with some mudstone. Some
coals appear in the lower part; Graces seam in the Nailsea Coalfield for
example.<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span>
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">The
Pennant deposition took place during the Bolsovian (Westphalian C) time which
is 308 – 311 million years ago.<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span>
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">The
Downend Formation is part of the Pennant Sandstone Group and is also known as
part of the Upper Coal Measures Group. It is exposed as the uppermost strata in
the Nailsea syncline. </span></span><span class="Apple-style-span" style="font-family: Verdana, sans-serif;">There
is also a small exposure at the road cutting at Bucklands batch, which is
passed on the road down the hill to the station. This exposure clearly shows
the dip of the strata forming the southern leg of the Nailsea syncline.</span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span>
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Other
exposures of Pennant Sandstone in the area occur at Conygar Quarry, Clevedon (private land), at a disused quarry, now Cloud Hill Industrial Estate and at
Highbury Hill, near the waterfall. Both are near Temple Cloud. There is also a
disused quarry where building stone for Bristol was extracted, at Troopers Hill
in St George. <o:p></o:p></span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><a href="http://www.troopers-hill.org.uk/">http://www.troopers-hill.org.uk/</a><o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><br /></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Lithological description<o:p></o:p></span></b></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Green-grey and blue-grey,
feldspathic, micaceous. Lithic arenites ( “Pennant “Sandstones ) of southerly
provenance, with thin mudstone/siltstone and seatearth interbeds and mainly
thin coals; the lithologies are commonly arranged in fining upwards channel-fill
sequences.<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><br /></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Thickness<o:p></o:p></span></b></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">c. 275m in the east of the
coalfield [c. SO 25 03 ] to c. 1350m in
the Swansea area [SS 73 94]<o:p></o:p></span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">330m maximum in the Nailsea area.<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Geographical limits<o:p></o:p></span></b></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Outcrops widely in the South
Wales Coalfield, from near Llanelly [SN
40 00] in the west to Pontypool [SO 25
03] in the east. It is also present in the Forest of Dean and Bristol
coalfields, and in the subsurface in the Oxfordshire and Berkshire coalfields.<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Type area<o:p></o:p></span></b></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Formation named after the
predominant “Pennant” sandstone facies of the South Wales coalfield, which provides
a “type area”.<o:p></o:p></span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><br /></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Lithology of Pennant Sandstone<o:p></o:p></span></b></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">It
is classified as a sandstone or arenite which means that the grains are
0.0625mm – 2mm in size. </span></span><span class="Apple-style-span" style="font-family: Verdana, sans-serif;">It
is feldspathic which means it contains clasts ( grains) of feldspar, an aluminosilicate mineral which makes up some 60% of the Earth’s crust. </span><span class="Apple-style-span" style="font-family: Verdana, sans-serif;">It
is also micaceous, meaning it contains a small proportion of clasts of biotite or
muscovite mica which is a hydrated aluminosilicate mineral.</span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Quartz makes up the majority of
the grains, which are cemented by silica.<o:p></o:p></span></span><br />
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span></div>
<div class="MsoNormalCxSpMiddle" style="line-height: 115%;">
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">This
composition suggests that Pennant sandstone is composed of the detrital remains
of granitic rocks. Granites are igneous
rocks which form volcanic plutons below the surface which may later be upthrust
or exposed by erosion of their roof. </span></span><span class="Apple-style-span" style="font-family: Verdana, sans-serif;">The
grains have polished surfaces which shows that they were transported by water (airborne grains have a ‘frosted’ surfaced). </span><span class="Apple-style-span" style="font-family: Verdana, sans-serif;">The
quartz grains survived the transport because they are very hard, being composed
of silicon dioxide. The rock itself is fairly soft.</span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><br /></span></span>
<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">In
some areas the grains are covered with different iron oxides which accounts for
the different colours seen. Red colouration is from iron whereas purple is indicative of managanese.<o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><br /></span></div>
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<span style="font-family: Verdana,sans-serif;"><b><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">Uses of Pennant sandstone<o:p></o:p></span></b></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="line-height: 115%; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;">It
has a long history of use as a building stone. </span></span><span class="Apple-style-span" style="font-family: Verdana, sans-serif;">As the grains are very hard and resistant to wear it is used as a high skid
resistant road material, especially at bends, traffic lights etc.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Richard Kefford</span><span class="Apple-style-span" style="font-family: Verdana, sans-serif;"><o:p></o:p></span></div>
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<span style="font-family: Verdana,sans-serif;"><span style="mso-bidi-font-size: 10.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-GB;"><b>References</b><o:p></o:p></span></span></div>
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<span style="font-family: Verdana,sans-serif;"><br /></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><a href="http://en.wikipedia.org/wiki/Pennant_sandstone">http://en.wikipedia.org/wiki/Pennant_sandstone</a><o:p></o:p></span></div>
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<span style="font-family: Verdana,sans-serif; font-size: x-small;"><br /></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><a href="http://en.wikipedia.org/wiki/Sandstone">http://en.wikipedia.org/wiki/Sandstone</a><o:p></o:p></span></div>
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<span style="font-family: Verdana,sans-serif; font-size: x-small;"><br /></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><a href="http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=PES">http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=PES</a><o:p></o:p></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif; font-size: x-small;"><br /></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif; font-size: x-small;">Green, GW. (1992) British
Regional Geology. Bristol and Gloucester region. BGS.<o:p></o:p></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif; font-size: x-small;">Published by NERC. ISBN 0 11
884482 2<o:p></o:p></span></div>
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<span style="font-family: Verdana,sans-serif; font-size: x-small;"><br /></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif; font-size: x-small;">BGS. England and Wales Sheet 264.
Solid and Drift Geology Map. 1:50 000 series.<o:p></o:p></span></div>
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<span style="font-family: Verdana,sans-serif; font-size: x-small;"><br /></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif; font-size: x-small;">BGS. Classical areas of British
Geology. Geological sheet ST 47 Solid and Drift.<o:p></o:p></span></div>
<div class="MsoNormalCxSpMiddle">
<span style="font-family: Verdana,sans-serif;"><span class="Apple-style-span" style="font-size: x-small;">Clevedon and Portishead. 1:25 000
series.</span><o:p></o:p></span></div>
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-34846819313096868072013-01-05T09:51:00.001-08:002013-01-05T09:51:41.578-08:00Free public lecture - 8th January<div dir="ltr" style="text-align: left;" trbidi="on">
<h1 style="text-align: center;">
<span style="font-family: Verdana,sans-serif;">Mapping of Volcanic Terrains across the Solar System</span></h1>
<h1 style="text-align: center;">
<span style="font-family: Verdana,sans-serif;"><i><span style="font-size: large;">Dr Ellen Stofan</span></i></span></h1>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtY53uisOvv-06D3nEwsGs5PNA4d4Y4aFRiKY4jAGJH3r8aDN3gzEuMIsG4dK4LAboz_iEhyphenhyphensSLWe2TlJo-JjGlZSQJ2yZfx8EbBIUwknnNPANpPUAT3kF5GEqKo7fwnObB92NOTmzO-km/s1600/Mars-Olympus_MOLA_MOC.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="161" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtY53uisOvv-06D3nEwsGs5PNA4d4Y4aFRiKY4jAGJH3r8aDN3gzEuMIsG4dK4LAboz_iEhyphenhyphensSLWe2TlJo-JjGlZSQJ2yZfx8EbBIUwknnNPANpPUAT3kF5GEqKo7fwnObB92NOTmzO-km/s320/Mars-Olympus_MOLA_MOC.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b><span style="font-family: Verdana,sans-serif;">Olympus Mons, Mars. Standing at 22km high (three times the height of Earth's own Mt Everest), it is the tallest volcano in the Solar System. Photo credit: European Space Agency</span></b></span></td></tr>
</tbody></table>
<br />
<span style="font-family: Verdana,sans-serif;"><strong>Venue: </strong>@Bristol (Anchor Road, Harbourside, Bristol, BS1 5DB - <a href="https://maps.google.co.uk/maps?q=At-Bristol,+Anchor+Road,+Bristol&hl=en&sll=51.454513,-2.58791&sspn=0.216931,0.605621&oq=at+bristol&hq=At-Bristol,+Anchor+Road,+Bristol&t=m&z=14">view map</a>) </span><br />
<span style="font-family: Verdana,sans-serif;"><strong>Date: </strong>8th January, 18.30 - 19.30<strong><br /></strong></span><br />
<span style="font-family: Verdana,sans-serif;"><strong>Location: </strong>Rosalind Franklin Room, At-Bristol<strong><br /></strong></span><br />
<span style="font-family: Verdana,sans-serif;"><strong>Admission: </strong>Free, lecture suitable over 12s - <span style="color: #cc0000;"><b>booking necessary</b></span> (</span><span style="font-family: Verdana,sans-serif;"><a href="http://solarvolcanos.eventbrite.co.uk/" target="_blank">Book Online </a></span><br />
<span style="font-family: Verdana,sans-serif;">Or phone 0845 4586499 [Monday - Friday, 9am - 5pm excluding Bank Holidays])</span><br />
<br />
<span style="font-family: Verdana,sans-serif;">Many planets and moons of our solar system show evidence of volcanic eruptions. </span><br />
<br />
<span style="font-family: Verdana,sans-serif;">The early missions to the Moon, Mars, Venus and Mercury were truly
missions of discovery, with great debates in the scientific community on
the roles of impacts and volcanic eruptions in shaping their surfaces.<br /><br />Join Dr.
Ellen Stofan to discuss how these alien volcanic features are mapped
and interpreted with knowledge and techniques developed from studies of
volcanoes on Earth. A perfect way to celebrate BBC Stargazing Live. <br /><br />This is a free lecture and is supported by the <a href="http://www.bristol.ac.uk/">University of Bristol</a>.</span><br />
<span style="font-family: Verdana,sans-serif;"><strong><br /></strong></span>
<span style="font-family: Verdana,sans-serif;"><span style="font-size: x-small;"><i>Original article: <a href="http://www.at-bristol.org.uk/1647.html">http://www.at-bristol.org.uk/1647.html</a></i></span><strong><br /></strong></span></div>
Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-38840154780654791632012-12-22T07:15:00.001-08:002013-02-04T15:14:43.275-08:00Merry Christmas from Avon RIGS<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="font-size: small;">Season's greetings to all of our readers. Outcrop is having a festive break but will be back in 2013 with some exciting new features.</span></div>
<div style="font-family: Verdana,sans-serif; text-align: center;">
<span style="font-size: small;"><br /></span></div>
<div style="text-align: center;">
<span style="color: #cc0000; font-size: large;"><span style="font-family: Verdana,sans-serif;">Merry <span style="color: #38761d;">Christmas</span> from <span style="color: #38761d;">Avon</span> RIGS</span></span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcJxqCCjHhmN7yyFyp4z6YF5UBsBEiyNf1i4XcOUSuJ8uNit8HgojIvanJBK1N4EVpN991DgHYJtFtTOrvmzOlmY2Y8bNZV18fv00G-FQBa08VVFIEjyCbNUlGN-QJJvLp5Cr9Vj6zlaPQ/s1600/Blaise+snow+walk+024.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcJxqCCjHhmN7yyFyp4z6YF5UBsBEiyNf1i4XcOUSuJ8uNit8HgojIvanJBK1N4EVpN991DgHYJtFtTOrvmzOlmY2Y8bNZV18fv00G-FQBa08VVFIEjyCbNUlGN-QJJvLp5Cr9Vj6zlaPQ/s320/Blaise+snow+walk+024.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: x-small;"><span style="font-family: Verdana,sans-serif;">Blaise Castle Estate in snow - from </span><a href="http://avonrigsoutcrop.blogspot.co.uk/2012/08/rigs-of-month-august-blaise-castle.html" style="font-family: Verdana,sans-serif;">August RIGS of the Month</a></span></b></td></tr>
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Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-3978721426489298938.post-11447973307894507252012-11-04T12:02:00.000-08:002012-11-06T19:08:43.738-08:00Geo-gardening - Sunday 21st October 2012<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="color: #222222;"><span style="font-family: Verdana, sans-serif;">John Toller was
joined by a very small group from <a href="http://www.wega.org.uk/">WEGA</a> to clean up the RIG site at Itchington
which the group had agreed to maintain. The site demonstrates a small but
excellent exposure of the "Bristol Time Gap". This shows the <a href="http://en.wikipedia.org/wiki/Unconformity#Angular_unconformity">angular unconformity</a> which separates the almost horizontal Triassic Mercian Mudstone
Group, locally Dolomitic Conglomerate, from the older, underlying and tilted
Carboniferous Limestone, which is known locally as Clifton Down Limestone. This was formed</span></span><span style="color: #666666; font-family: 'Arial Unicode MS', Arial, sans-serif; font-size: 11px;"> </span><span style="font-family: Verdana, sans-serif;">approximately 334 to 341 million years ago in the Carboniferous Period. </span><br />
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<span style="color: #222222;"><span style="font-family: Verdana, sans-serif;">The Carboniferous
Limestone was deposited in warm shallow seas covering much of the country. This
was followed by the Coal Measures and then thick layers of sandstone lain down
by river deltas until the start of the Permian Period. No Permian rocks are
present here, but during that period the continents were all brought together
to form one huge landmass, called Pangaea.</span></span></div>
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<span style="color: #222222;"><span style="font-family: Verdana, sans-serif;">The Carboniferous rocks here were folded and
compressed to form mountains, then weathered and eroded down to produce more
sediments. The layers overlying the limestone here are products of that
erosion during the Triassic Period, resting on the worn down limestone surface. The environment by then
had changed to mainly desert, resulting in characteristic reddish sands, clays
and debris as seen here, contrasting with the hard grey limestone. The time gap
between the two layers is at least 50 million years, enough time for a whole
mountain range to be created and worn down. <o:p></o:p></span></span></div>
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<span style="color: #222222;"><span style="font-family: Verdana, sans-serif;">The rock face had
become covered in a fine variety of plants and saplings which were threatening
to completely engulf it. The many ash sapling were especially unwelcome as the
strong roots can quickly penetrate the joints and fissures in the rock to break
down the exposure. After a couple of hours determined clearance the
unconformity was looking very much more obvious, as John is pointing out in the
photo. Next year it will all need doing again or the ash will take hold, so
keep the clippers handy! <o:p></o:p></span></span></div>
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<span style="color: #222222;"><span style="font-family: Verdana, sans-serif;">To admire this
site, take the turning from the A38 at the Grovesend road
junction near Thornbury signposted to The Slad and Itchington. Keep travelling
until you are about to go under the M5 and see the exposure on the right. Close
by you can also see a beautifully flat natural bedding plane of limestone
forming a bank. The exposures are fenced off and there is always a danger of
falling rocks, so keep at a safe distance. </span></span><br />
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><b><span style="color: #222222;"><span style="font-family: Verdana, sans-serif;">Photo credit: Sandi Shallcross</span></span></b></span></td></tr>
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<span style="color: #222222; font-family: Courier New, Courier, monospace;">Sandi Shallcross</span></div>
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Richardhttp://www.blogger.com/profile/03202231236602018956noreply@blogger.com0