The BGS Lexicon of Named Rock Units — Result Details

Lligwy Sandstone Formation

Computer Code: LGY Preferred Map Code: notEntered
Status Code: Full
Age range: Holkerian Substage (CQ) — Asbian Substage (CR)
Lithological Description: Cross-bedded sandstones, pebbly sandstones and conglomerates with subordinate siltstone and mudstone beds. Records fluvial deposition along the margin of the North Wales Dinantian platform throughout the late Asbian.
Definition of Lower Boundary: Rests unconformably on ?Devonian, Ordovician and Precambrian rocks (Mona Complex).
Definition of Upper Boundary: Overlain and passes laterally into thick-bedded limestones of the Loggerheads Limestone Formation.
Thickness: To 60m
Geographical Limits: Between Llangefni [SH4675] and Lligwy Bay, [SH5087], Anglesey, North Wales.
Parent Unit: Not Applicable (-)
Previous Name(s): Basement Conglomerate (Anglesey) [Obsolete Name And Code: Use LGY] (BCA)
Basement Beds Formation [Obsolete Name And Code: See Supplementary Information] (BED)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Northwest facing slopes, east of Afon Lligwy, Anglesey. Crags and small quarries provide intermittent exposures in the upper part of the Formation. Greenly, 1919. 
Reference(s):
Davies, J R. 1983. The stratigraphy, sedimentology and palaeontology of the Lower Carboniferous of Anglesey. Unpublished PhD thesis, University of Keele. 
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. 
Greenly, E. 1919. Geology of Anglesey. Memoir of the Geological Survey, UK. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E094