The BGS Lexicon of Named Rock Units — Result Details

Sandstone And Marl Group

Computer Code: SAM Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Lochkovian Age (DO) — Pragian Age (DP)
Lithological Description: Red or green siltstones (marls). Red, sometimes nodular mudstones, very fine- to fine-grained, bright green or purple sandstones and intra-formational conglomerates. (Sandstone and Marl Group = division of Red Marls).
Definition of Lower Boundary: Drawn at base of feldspathic grits and breccias and grey shales of the Sandstone and Marl Group where they rest conformably on purple marl of the Lower Marl Group.
Definition of Upper Boundary: Drawn at conformable upward passage from red marls of the Sandstone and Marl Group to siltstones of the Upper Marl Group.
Thickness: Approx. 200 metres - 275 metres.
Geographical Limits: Southwest Wales.
Parent Unit: Not Entered (?)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  South Pembrokeshire, Dyfed, Wales. 
Reference(s):
King, W W. 1934. The Downtonian and Dittonian strata of Great Britain and north-western Europe. Quarterly Journal of the Geological Society of London, Vol. 90, 526-570. 
House, M R, Richardson, J B, Chaloner, W G, Allen, J R L, Holland, C H and Westoll, T S. 1977. A Correlation of Devonian rocks of the British Isles. Geological Society of London, Special Report No.8, Scottish Academic Press, Edinburgh. 
Dixon, E E L, 1921. The Geology of the South Wales Coalfield, Part XIII , the country around Pembroke and Tenby, being an account of the region comprised in sheets 244 and 245. Memoir of the Geological Survey of Great Britain (HMSO). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable