The BGS Lexicon of Named Rock Units — Result Details

Lilstock Formation

Computer Code: LTK Preferred Map Code: notEntered
Status Code: Full
Age range: Rhaetian Age (TR) — Rhaetian Age (TR)
Lithological Description: Includes Cotham Member (grey and grey-green shales and siltstones) and Langport Member (porcellanous limestone below, calcareous mudstone above).
Definition of Lower Boundary: Placed at base of Cotham Member, sharp, commonly channeled on the Westbury Formation.
Definition of Upper Boundary: Placed at top of Langport Member, where there is a sharp but conformable junction with the overlying 'paper shale' of the "Blue Lias".
Thickness: 1-10m
Geographical Limits: Present throughout the United Kingdom.
Parent Unit: Penarth Group (PNG)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Area  Lilstock, west Somerset. 
Reference Section  Immediately north of Lavernock Point, south Glamorgan. 
Reference Section  Lilstock, west Somerset. 
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:
E127 E142 E141 E341 E342 E264