The BGS Lexicon of Named Rock Units — Result Details

Basement Beds Formation [Obsolete Name And Code: See Supplementary Information]

Computer Code: BED Preferred Map Code: Bed
Status Code: Index Level
Age range: Chadian Substage (CI) — Asbian Substage (CR)
Lithological Description: Purple and green shales, interstratified with bands of purplish or grey limestone, red, yellow and white sandstone and red marl. Conglomerates locally.
Definition of Lower Boundary: Unconformable on underlying rocks (Silurian/Ordovician).
Definition of Upper Boundary: Base of overlying dark, bedded, fine-grained limestones or sandstones (Llanarmon Limestone, Llwyn-y-Fran Sandstone, Ty-nant Limestone).
Thickness: To about 100m
Geographical Limits: See extents of replacment terms: Lligwy Sandstone; Menai Straits; Ffernant; Penbedw; Fron Fawr; Pant formations.
Parent Unit: none recorded or not applicable
Previous Name(s): Old Red Sandstone (-3838)
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Waters, C N, Waters, R A, Barclay, W J, and Davies, J R. 2009. Lithostratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/09/01. 184pp. 
Strahan, A, 1890. The Geology of the Neighbourhoods of Flint, Mold and Ruthin. Memoir of the Geological Survey, Sheet 79SE (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E121 E137