The BGS Lexicon of Named Rock Units — Result Details

Westleigh Limestone Formation

Computer Code: WST Preferred Map Code: notEntered
Status Code: Full
Age range: Visean Stage (CV) — Visean Stage (CV)
Lithological Description: Lower part (known informally as the Lower Westleigh Limestone) comprises thin-bedded, platy, fine-grained (mud and silt grade), commonly partly silicified limestones. Shaly mudstone interbeds are sparsely developed. Upper part (known informally as the Upper Westleigh Limestone) comprises thin to massive beds of coarse, locally conglomeratic, bioclastic/ooidal/pelloidal calcarenite interbedded with subordinate mudstones and calcilutites. Silicification is locally present. The Lower Westleigh Limestone is present only around Westleigh; to the north it passes into the Upper Westleigh Limestone.
Definition of Lower Boundary: Around Westleigh the lower boundary is taken at the incoming of thin-bedded fine-grained limestones of the (lower) Westleigh Limestone Formation above the black, hard cherty mudstones of the underlying Doddiscombe Formation. To the north it is taken at the incoming of thin to thick bedded coarse calcarenites and mudstones of the (upper) Westleigh Limestone Formation above the black hard cherty mudstones of the underlying Doddiscombe Formation.
Definition of Upper Boundary: The upper boundary is taken at the incoming of dark grey unfossiliferous finely laminated silty mudstones with scattered siltstones of the overlying Dowhill Mudstone Formation above the highest limestone bed of the Westleigh Limestone Formation.
Thickness: Not known but probably c.100m.
Geographical Limits: Between Ashbrittle (ST 04 21), and Wellington (ST 13 20), Somerset.
Parent Unit: Teign Valley Group (TEVY)
Previous Name(s): Westleigh Limestones (-2540)
Upper Westleigh Limestones (-4985)
Upper Westleigh Limestone [Obsolete Name And Code: See WST] (UWST)
Lower Westleigh Limestones (-1287)
Lower Westleigh Limestone [Obsolete Name And Code: See WST] (LWST)
Westleigh Limestone Group (-3771)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Disused West Whipcott Quarry, 1.5km north of Westleigh, east Devon. Section exposes 25m of folded and faulted thin- to thick-bedded limestones and mudstones of the (Upper) Westleigh Limestone Formation. Whiteley (2004). 
Type Area  Westleigh, Devon, England. 
Reference(s):
Thomas, J M, 1962. The Culm Measures in Devon and north-west Somerset east of Bampton. PhD Thesis, University of London. 
Thomas, J M. 1963a. Sedimentation in the Lower Culm Measures round Westleigh, northeast Devon. Proceedings of the Ussher Society, Vol.1, 71-72. 
Thomas, J M, 1963b. The Culm Measures succession in northeast Devon and northwest Somerset. Proceedings of the Ussher Society, Vol.1, 63-64. 
Whiteley, M J. 2004. Culm Trough. 477-504 in British Lower Carboniferous Stratigraphy. Cossey, P J, Adams,A E, Purnell, M A, Whiteley, M J, Whyte, M A and Wright, V P (editors). Geological Conservation Review Series, No 29. (Peterborough: Joint Nature Conservation Committee). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E310 E311