The BGS Lexicon of Named Rock Units — Result Details

Pant Y Darren Formation

Computer Code: PYDN Preferred Map Code: notEntered
Status Code: Full
Age range: Courceyan Substage (CF) — Courceyan Substage (CF)
Lithological Description: Fine-grained, thinly bedded dolostones with minor mudstone layers.
Definition of Lower Boundary: The base is a sharp, planar boundary on which the basal dolostone of the Pantydarren Formation overlie ooidal grainstone of the underlying Pwll-y-Cwm Formation.
Definition of Upper Boundary: The top is a sharp junction where dolostones of the Pantydarren Formation are overlain by ooidal grainstones of the Blaen Onnen Oolite Formation.
Thickness: 5m
Geographical Limits: Northeast crop of the South Wales Coalfield, from Darren Disgwlfa [SO 217 145] southeast to around Craig-yr-Hafod [SO 2720 1001].
Parent Unit: Clydach Valley Subgroup (CLD)
Previous Name(s): Bed 3 (-4280)
Alternative Name(s): Pantydarren Formation
Pantydarren Beds
Stratotypes:
Type Area  Disused quarries at Coed Pantydarren, 1km north of the Clydach Gorge, near Brynmawr, south Wales, which expose 5m of fine-grained, thin-bedded dolomites of the Pantydarren Formation sharply overlying massive pale grey ooildal grainstones of the Pwll-y-Cwm Oolite Formation. Barclay, 1989. 
Reference Section  Roadside section on the old Brynmawr road at Blackrock, where the entire formation, lower boundary (with the Pwll-y-Cwm Oolite Formation) and upper boundary (with the Blaen Onnen Oolite Formation) are exposed. Barclay,1989. 
Reference(s):
Barclay, W J, Jackson, D I, Mitchell, M, Owen, B, Riley, N J, White, D E, Strong, G E and Monkhouse, R A. 1989. Geology of the South Wales Coalfield, Part II, the country around Abergavenny. Memoir of the British Geological Survey. 
George, T N. 1954. Pre-Seminulan Main Limestone of the Avonian Series in Breconshire. Quarterly Journal of the Geological Society of London, Vol.110, 282-322. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable