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.

Friday, 25 August 2017

"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.).".

Thanks to David for his work.

The following information is from the BGS Lexicon of Named Rock Units.
Accessed 21st August 2017

Saltford Shale Member

Computer Code:SASHPreferred Map Code:SaSh 
Status Code:Full 
Age range:Rhaetian Age (TR) — Hettangian Age (JH) 
Lithological Description:Mostly grey, fissile or blocky, fossiliferous calcareous mudstones; a few limestones. 
Definition of Lower Boundary: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). 
Definition of Upper Boundary:Placed at the base of an interbedded argillaceous limestone ('cementstone') and mudstone sequence. At base of Bed 22 at type section. (Donovan, 1956). 
Thickness:4.27m at type section, 20-30m over most of Midlands. 
Geographical Limits:Central and southern Midlands. 
Parent Unit:Blue Lias Formation (BLI)
Previous Name(s):Angulata Beds (-2408)
Psiloceras Shales (-4871) 
Alternative Name(s):none recorded or not applicable
Type Section Section at Saltford railway cutting southeast of Keynsham, Somerset (Donovan, 1956, p.182-212). 
Reference Section BGS Twyning Borehole, 82.25 to 114.80m depth. 
Reference Section BGS Stowell Park Borehole, 1932' 0" to 2028' 6" depth. 
Donovan, D T, 1956. The zonal stratigraphy of the Blue Lias around Keynsham, Somerset. Proceedings of the Geologists' Association, Vol.66, p. 182-212. 
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). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E183 E169 E199 E264

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