The BGS Lexicon of Named Rock Units — Result Details

Clyst St Lawrence Formation

Computer Code: CLSL Preferred Map Code: CSL
Status Code: Full
Age range: Early Triassic Epoch (TE) — Early Triassic Epoch (TE)
Lithological Description: Reddish brown silt and sand, ranging from sand, through silty sand, silty clayey sand, sandy silt, clayey silt, and sandy clayey silt; the sand content is mainly fine- to very fine-grained. Probably sandstone and siltstone where unweathered.
Definition of Lower Boundary: Rests unconformably on Crackington Formation between Westwood (SY 020 990) and Clyst Hydon; elsewhere contacts faulted. Near Cullompton (in Sheet 310) apparently rests unconformably on Bude Formation and Cadbury Breccia.
Definition of Upper Boundary: Passes gradationally upwards into reddish brown silty mudstones of the undivided Aylesbeare Mudstone.
Thickness: 30-50m
Geographical Limits: Outcrop extends from Westwood (SY 020 990), northwards through Clyst St Lawrence (ST 030 001) to Langford Green (ST 030 030) and Mutterton (ST 030 050).
Parent Unit: Aylesbeare Mudstone Group (AYB)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Area  Clyst St Lawrence village. No suitable stratotype section. Sporadic small trackside and stream bank exposures across outcrop. Several small exposures in lane in Clyst St Lawrence between Town Farm and Foretown.(ST 0281 0002 - 0292 0007). 
Edwards, R A, 1988. Geology of the Clyst Hydon District (Devon). British Geological Survey Technical Report, WA/88/4. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable