The Group's aim is to identify, survey, protect and promote geological and geomorphological sites in the former County of Avon - the modern unitary authorities of Bath and North East Somerset, Bristol, North Somerset and South Gloucestershire. RIGS are selected for their educational, research, historical and aesthetic value.

Wednesday, 22 February 2012

Follow us on Twitter!

To keep up to date with the latest offerings from the blog, local news and events, and links to other geological goings on in the South-West, follow us on Twitter! @AvonRIGS

Wednesday, 15 February 2012

Public lecture at the Wills Memorial Building, Bristol - 13th March

WEGA - the West of England group of the Geologists' Association

Medical origins of the Geological Society

Dr Cherry Lewis - Bristol University

Tuesday 13th March - 7.30pm

Cherry Lewis' interests lie in the history of geology and she has published a popular science book on the history of dating the age of the Earth entitled: 'The Dating Game: One Man's Search for the Age of the Earth'. Cherry’s talk will cover the origins of the Geological Society of London, which was founded on 13 November 1807 – the oldest such society in the world. Founding members include James Parkinson (1755-1824) who gave his name to Parkinson's Disease.

A journey to the centre of the Earth (in BS8)

Bristol Experimental Earth STudies (BEEST) is one of seven research groups in the Earth Sciences department at the University of Bristol. Its primary activities involve conducting experiments to probe deep into the Earth’s interior. The BEEST labs consist of a series of experimental apparata that are capable of replicating the conditions at which igneous rocks are created, from lava flows at the surface down to the core-mantle boundary and everything in between. Experiments can either be conducted on natural rocks or synthetic mixes of chemicals. The latter option has the advantage of allowing us to simplify complex natural systems and control the amount of volatiles (such as CO2 and H2O) in the sample.

  • Lava flows = 1 atmosphere furnace: This is in effect a gloried oven, though it is a little hotter than you might use for your Sunday roast! Samples are lowered on a wire into the hotspot of the furnace via a vertical pipe and are heated to temperatures of up to 1700ºC at room pressure and atmospheric conditions. It is primarily used for studying the changes in mineralogy of lava erupted onto the Earth’s surface.
Lava flows can be costly volcanic hazards, destroying property and agricultural land; however, certain types of lava can be economic assets. Dr Richard Brooker is using a 1 atmosphere furnace to look at the properties of kimberlites, lavas that are famous for their propensity to carry diamonds.

  • Shallow magma chambers = cold seal pressure vessel: This piece of equipment allows us to simulate conditions where magma is stored beneath active volcanoes. Samples are enclosed in small metal capsules and inserted into a metal tube, called a bomb. The bomb is then flooded with water which creates a pressure on the capsule corresponding to being at a depth of 1-6km below the surface of the Earth. Finally, temperatures are elevated to ≤900ºC using an electric current. The decrease of pressure and temperature can be controlled such that we can accurately simulate the eruption of a volcano.
A cold seal pressure vessel being operated by Bristol PhD student, Jenny Riker. Jenny is investigating how decompression drives crystallisation in erupting magma at Mt St Helens (pictured left).

  • Lower crust and mantle = piston cylinder and multi-anvil apparatus: As we descend deeper into the Earth, the amount of pressure we need to apply to a sample increases dramatically. These two pieces of equipment do this by squeezing the metal capsule between differently shaped blocks of metal; however, the greater the pressure needed, the smaller the sample must be. The capsules used are typically <5mm in length and must be analysed using high magnification electron microscopy. The piston cylinder can simulate up to 120km depth and 1400ºC; this makes it an excellent device for studying how magmas are generated in subduction zones. The multi-anvil can probe much deeper, up to the core-mantle boundary, and is used to investigate the state of the Earth’s molten mantle.

The piston cylinder apparatus can be used to simulate conditions where magma is generated at island arcs: pressure is applied manually using a lever. PhD student Charly Stamper is conducting experiments at lower crustal depths to gain insights into the magma chamber beneath Grenada, Lesser Antilles.

Carbonatites are carbonate-rich igneous rocks. Oldoinyo Lengai in Tanzania (above left) is currently the world's only active carbonatite volcano although pyroclastic carbonatite deposits have also been discovered in Europe. Sorcha McMahon's PhD is focussed on how these strange magmas form, using the multi-anvil apparatus (above right). High pressures are achieved placing samples within an octahedral ceramic pressure cell, at the centre of 8 carbide cubes (see inset).

  • Core = diamond anvil cell (DAC): In order to replicate conditions at the centre of the Earth, we need to employ the hardest substance known to man-kind, diamond. The most astonishing aspect of this equipment is that the DAC is small enough to fit into the palm of your hand! Sample powder is placed between two diamond tips and heated using a laser. The samples are so small that analysis must be carried out at a synchrotron, such as CERN, using the high-energy x-rays generated by particle acceleration. Applications of this technique include testing the hypothesis that the Earth’s iron core contains small amounts of a light element, such a carbon or silicon.

A diamond anvil cell (DAC) can replicate the pressures and temperatures found deep within the Earth. Andrew Thomson and others at Bristol are using a DAC to study the chemistry of the Earth’s core.
All this equipment can be found in three rooms in the basement of the Wills Memorial Building. It just goes to show you can take a journey to the centre of the Earth without leaving Bristol!

For more information:
Department of Earth Sciences at the University of Bristol - http://www.gly.bris.ac.uk

Charly Stamper, BEEST PhD student

This post also appears in http://bristoluniversityfacultyofscience.blogspot.com - University of Bristol Science Faculty blog

Tuesday, 7 February 2012

Public lecture - Friday 10th Feb - Wills Memorial Building

"Our solar system is a blend of the effluvia from many stellar explosions. By making high precision isotope ratio measurements on different meteorites we have been able to fingerprint the source of the most recently added material. We identify a supernova component from a massive star, which is in keeping with a longstanding hypothesis for triggered nebula collapse and subsequent planetary

The Bristol Dinosaur Project

Did you know, Bristol has its very own dinosaur? Thecodontosaurs antiquus (the ancient socket toothed lizard) was discovered in 1834 by Samuel Stutchbury in a quarry on Durdham Downs (now known as Quarry Steps, a SSSI that is a tiny sliver of the original quarry) and became the 5th dinosaur ever described; it has not since been found anywhere else in the world. Thecodontosaurs antiquus dates from over 200 million years ago back when Bristol was an archipeligo of islands and shallow, tropical seas. In 2011, the Bristol Dinosaur celebrated 175 years of holding its species name.

  Tooth of the Bristol dinosaur from the Tytherington fissure.  Found by one of the volunteers.

Some the specimens from quarry were housed in the Bristol Geological Museum. In November 1940, the Blitz struck Bristol hard.  Huge areas were bombed out including the strip of buildings at the top of Park Street.  Many of the collections were lost, either directly to the bombing or the clean-up crews after; fortunately some of the bones were housed in a cave in the Avon Gorge alongside some precious paintings, safely away from the threat of bombers. About half of the original Thecodontosaurus specimens were rescued and are housed in the current Bristol Museum & Art Gallery

In the 1970s more bones from the dinosaur were found at a quarry in Tytherington, South Gloucestershire when over 4 tonnes of material was collected. Remmert Schouten at the University of Bristol works a preparator thanks to funding received from the Leverhulme trust.  Since his appointment the material has been worked on for scientific purposes and teaching students about preparation techniques.  In 2009, the Heritage Lottery Fund awarded £294,000 for 3 years of funding to improve the lab facilities, hire another preparator, and pay for a learning officer to increase public knowledge of this unique specimen.  The project has been so successful since receiving the funding that over 11,000 school children have had workshops delivered by the learning officer. Many postgraduate students from the School of Earth Sciences have also been trained to deliver the workshops in schools and become STEM (Science, Technology, Engineering and Maths) Ambassadors.  It in fact the outreach work has lead to the School of Earth Sciences winning the Best STEM University Department of 2011 in the West.

Some of the primary aged students with various activities from the Bristol Dinosaur Project.  The outreach activities include are handling specimens, a life sized jigsaw puzzle with replica bones and a talk.

If you are interested in getting involved or want to know more please check us out at Bristol Dinosaur Project website (www.bristoldinosaurproject.co.uk).  We are running a competition for artists to show us what they think Thecodontosaurus looked like when it was alive.  Otherwise look out for us at various events around Bristol, be it schools, museums, Festival of Nature, dinosaur days at the Arnos Vale etc. where we will be giving workshops.

Andrew Cuff, Bristol Dinosaur Project