The BGS Lexicon of Named Rock Units — Result Details

Telpyn Point Sandstone Formation

Computer Code: TELPP Preferred Map Code: notEntered
Status Code: Full
Age range: Kinderscoutian Substage (CK) — Yeadonian Substage (CY)
Lithological Description: Fluvial, fine- to coarse-grained, locally pebbly and conglomeratic, pale grey, quartzitic sandstones with thin argillaceous mudstone/siltstone and seatearth interbeds; sporadic, thin coals in the argillaceous beds.
Definition of Lower Boundary: The base is placed at the base of the lowermost quartzitic sandstone of the formation, where it overlies a sharp surface or erosion surface cut in the underlying mudstones of the Bishopston Mudstone Formation. At the type section at Telpyn Point, the boundary is placed at the base of a fine-grained quartzitic sandstone at 27.66m (90' 9") below the top of the section measured by Archer (1965).
Definition of Upper Boundary: The top is placed at the top of the highest quartzitic sandstone of the Formation, immediately or close below the base of the dark grey fossiliferous mudstones of the Subcrenatum Marine Band. Note that, for practical mapping purposes, any development of thin non-marine beds between the top of the highest quartzite and the base of the Subcrenatum Marine Band are included in the Telpyn Sandstone Formation. There are 8.7m of these at Telpyn Point and 7.62m at Settling Nose.
Thickness: 18.97m at type section to 21.3m at Settling Nose.
Geographical Limits: Around the margins of the Pembrokeshire Coalfield, and on the east crop of the main South Wales Coalfield, from the Clydach Valley south to Blaenserchan.
Parent Unit: Marros Group (MARR)
Previous Name(s): Farewell Rock [Obsolete Name] (FR)
Upper Sandstone Group (-1226)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Foreshore and cliff section at Telpyn Point, Pembrokeshire. All but the very topmost beds immediately below the Subcrenatum Marine Band are exposed and comprise 8.7m of silty mudstones and striped beds above 18.97m (62' 4") of fine-grained quartzitic sandstone. Archer, 1965; George, 1982, 2001. 
Reference Section  Foreshore exposures at Settling Nose, Pembrokeshire, where 7.62m of mudstones overlie 21.33m of quartzitic sandstone. Archer, 1965. 
Reference(s):
Waters, C N, Barclay, W J, Davies, J R and Waters, R A. In press. Stratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/05/06. 
Archer, A A. 1995. Notes on the Millstone Grit of the north crop of the Pembrokeshire Coalfield. Proceedings of the Geologists' Association, Vol.76, 137-150. 
George, G T. 1982. Sedimentology of the Upper Sandstone Group (Namurian G1) in south-west Dyfed: a case study. Geological excursions in Dyfed, southwest Wales. Bassett, M G (Editor). 203-214. 
George, G T, 2001. Late Yeadonian (Upper Sandstone Group) incised valley supply and depositional systems in the South Wales peripheral foreland basin; implications for the evolution of the Culm Basin and for the Silesian hydrocarbon plays of onshore and offshore UK. Marine and Petroleum Geology, Vol.18, 671-706. 
Hampson, G J. 1998. Evidence for relative sea-level falls during deposition of the Upper Carboniferous Millstone Grit, South Wales. Geological Journal, Vol.33, 243-266. 
Ware, W D. 1939. The Millstone Grit of Carmarthenshire. Proceedings of the Geologists' Association, Vol.50, 168-204. 
George, G T and Kelling, G. 1982. Stratigraphy and sedimentology of Upper Carboniferous sequences in the coalfield of southwest Dyfed. 175-201 in Bassett, M G (Editor), Geological excursions in Dyfed, south-west Wales. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable