The BGS Lexicon of Named Rock Units — Result Details

Pen-Y-Garnedd Limestone Formation

Computer Code: PGD Preferred Map Code: Pgd
Status Code: Full
Age range: Onnian Substage (ON) — Onnian Substage (ON)
Lithological Description: Limestone and dolomite.
Definition of Lower Boundary: Overlies mudstones of the Allt-tair-ffynnon Formation.
Definition of Upper Boundary: Overlain by black phosphatic mudstones of the Nod Glas Formation, locally unconformably overlain by mudstones and siltstones of the Laundry Mudstone Formation.
Thickness: c. 17m at Pen-y-garnedd, (Wedd et al., 1929).
Geographical Limits: The Pen-y-garnedd Limestone Formation and overlying Nod Glas Formation in much of the Ordovician of North Wales, in particular in the Llantyllin syncline at Oswestry (137) and around Meifod (151) and Dinas Mawddwy (150).
Parent Unit: Not Applicable (-)
Previous Name(s): Pen Y Garnedd Limestone (-1758)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Old quarry at Pen-y-garnedd. 
Reference(s):
Wedd, C B, Smith, B, King, W B R and Wray, D A. 1929. Geology of the country around Oswestry. Memoir of the Geological Survey of Great Britain, Sheet 137. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E136 E137