The BGS Lexicon of Named Rock Units — Result Details

WESTBURY FORMATION
Computer Code: WBY  Status Code: FORMAL ENTRY 
Preferred Map Code: Wby 
Age or Age Range: [ TR ] RHAETIAN  to [  ]  
Lithological Description:
Dark grey mudstones or shales with subordinate thin limestones, sandstones and fossiferous arenaceous units ('bone beds'). 
Definition of Lower Boundary:
Usually non-sequential with underlying Blue Anchor Formation, locally transitional. 
Definition of Upper Boundary:
Placed at locally transitional junction with overlying Cotham Member of the Lilstock Formation. 
Thickness:
5-10m 
Geographical Limits:
Present throughout United Kingdom outcrop area. 
Parent Unit: Parent Unit Code:
PENARTH GROUP  PNG
Previous Name(s): Previous Code(s):
CONTORTA SHALES   
WESTBURY BEDS   
BLACK SHALES   
LOWER RHAETIC  LRRH 
Alternative Name(s):
none recorded or not applicable
Stratotypes:
Reference Section  Coastal section, St Mary's Well Bay, Penarth, South Glamorgan. 
Reference Section  Coastal section north of Lavernock Point, south Glamorgan. 
Type Area  Village of Westbury-on-Severn, Gloucestershire. 
Reference(s):
Waters, R A and Lawrence, D J D, 1987. Geology of the South Wales Coalfield - Part III: the country around Cardiff. Memoir of the British Geological Survey, Sheet 263. (England and Wales). 
Warrington, G, Audley-Charles, M G, Elliott, R E, Evans, W B, Ivimey-Cook, H C, Kent, P E, Robinson, P L, Shotton, F W, and Taylor, F M. 1980. A correlation of the Triassic rocks in the British Isles. Special Report of the Geological Society of London, No.13. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
Map Code Sheet Name
E  183
E  127
E  72
E  199
E  202
E  141
E  142

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