The BGS Lexicon of Named Rock Units — Result Details

Pant Mawr Sandstone Member

Computer Code: PMSA Preferred Map Code: notEntered
Status Code: Full
Age range: Asbian Substage (CR) — Asbian Substage (CR)
Lithological Description: Partially dolomitised, sandy,skeletal packstone in lower part, and thin-bedded, cross bedded fine-grained calcareous sandstone in upper part. Represents transgressive shoreface deposits.
Definition of Lower Boundary: Taken at the sharp contact, defined by a palaeokarstic surface, between the calcite mudstones and skeletal/peloidal/ooid packstone/grainstones of the underlying Stormy Limestone Formation and the overlying, partially dolomitised, sandy skeletal packstones and calcareous sandstones of the Member.
Definition of Upper Boundary: Taken at the sharp junction at the top of the calcareous sandstones of the Member and the overlying thick-bedded, fine- to coarse-grained , mottled and pseudobrecciated skeletal packstones of the remainder of the Oxwich Head Limestone Formation.
Thickness: 1.5 to 4m
Geographical Limits: Western Vale of Glamorgan [ST 00 74]. May pass north into the coeval Honeycombed Sandstone Member on the north crop of the South Wales Coalfield [SN 97 13].
Parent Unit: Oxwich Head Limestone Formation (OHL)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Section  Pant Mawr Quarry, 1km northwest of Mount Pleasant Farm, South Cornelly, Vale of Glamorgan. Entire unit present, comprising dolomitised sandy limestone passing up into calcareous sandstone. Lower contact with underlying Stormy Limestone Formation seen; upper contact with overlying undivided Oxwich Head Limestone Formation also exposed. 
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