The BGS Lexicon of Named Rock Units — Result Details

Stormy Limestone Formation

Computer Code: STYL Preferred Map Code: notEntered
Status Code: Full
Age range: Holkerian Substage (CQ) — Asbian Substage (CR)
Lithological Description: Interbedded cryptalgal and fenestral, calcite mudstones, coquinoid limestones, skeletal, peloid, intraclast, ooid packstone/grainstones, ooid grainstones and the characteristic oncolitic grainstones. Scattered algal bioherms. Deposited in a peritidal enviroment.
Definition of Lower Boundary: Taken at the base of the first bed of calcite mudstone occuring above the ooid grainstones and the subordinate skeletal packstones of the underlying Cornelly Oolite Formation.
Definition of Upper Boundary: In the Vale of Glamorgan the top is taken at the sharp contact, defined by a paleokarstic surface, between the heterolithic lithologies of the Formation and the overlying partially dolomitised sandy skeletal packstones and calcareous sandstones of the Pant Mawr Sandstone Member [Oxwich Head Limestone Formation]. In Gower and Pembrokeshire it is taken at the palaeokarstic surface separating the heterolithic lithologies of the Formation from the mottled and pseudobrecciated skeletal packstones of the Oxwich Head Limestone Formation.
Thickness: 55 to 65m in the central and western Vale of Glamorgan.
Geographical Limits: West and central Vale of Glamorgan [ST 00 74]. Present also in Gower [SS 50 90] and the Pembroke/Tenby [SM 99 01] area but has not been mapped. Passes laterally eastwards into the Hunts Bay Oolite Subgroup, that cannot be subdivided into Cornelly Oolite and Stormy Limestone formations.
Parent Unit: Hunts Bay Oolite Subgroup (HBO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Stormy Down Quarry, 500m southeast of Ballas Farm, South Cornelly, Vale of Glamorgan. Lower third of unit exposed, comprising heterolithic peritidal limestones. Lower contact with underlying Cornally Oolite Formation seen; upper contact with Oxwich Head Limestone Formation not seen. 
Reference(s):
Wilson, D, Davies, J R, Fletcher, C J N, and Smith, M. 1990. The Geology of the South Wales Coalfield, part VI the Country around Bridgend. Memoir of the British Geological Survey, 1:50 000 Geological Sheets 261 and 262 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E261 E262