The BGS Lexicon of Named Rock Units — Result Details

Penbedw Formation

Computer Code: PDW Preferred Map Code: notEntered
Status Code: Full
Age range: Chadian Substage (CI) — Chadian Substage (CI)
Lithological Description: Red and green mottled mudstones, sandstones, conglomerates and basal breccias. The Penbedw Formation represents localised accumulations of terrestrial scree and alluvial deposits in palaeovalleys and embayments along the margin of the North Wales Dinantian platform
Definition of Lower Boundary: Rests unconformably on cleaved and folded Silurian mudstones,siltstones and sandstones.
Definition of Upper Boundary: Conformable contact with limestones of the Foel Formation
Thickness: To 4m
Geographical Limits: The formation comprises a series of disconnected bodies occurring beneath the Clwyd Limestone Group along the eastern side of the Clwydian Range (SJ 17 67) northeast Wales.
Parent Unit: Not Applicable (-)
Previous Name(s): Basement Beds Formation [Obsolete Name And Code: See Supplementary Information] (BED)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Alyn Valley Borehole (SJ 15 NE/8), Pistyll Gwyn Quarry. The Borehole penetrated complete 3.5m-thick sequence of reddened breccias, conglomerates and sandstones resting on weathered Silurian mudstones at a depth of 121.50m Davies et al., (in press) 
Type Area  Stream north of Penbedw Hall, Near Nannerch, in which red "shales" were formerly exposed. Davies et al., (in press) 
Reference(s):
Strahan, A, 1890. The Geology of the Neighbourhoods of Flint, Mold and Ruthin. Memoir of the Geological Survey, Sheet 79SE (England and Wales). 
Waters, C N, Barclay, W J, Davies, J R and Waters, R A. In press. Stratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/05/06. 
Davies, J R, Wilson, D and Williamson, I T. 2004. Geology of the country around Flint. Memoir for 1:50 000 Geological Sheet 108. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable