The BGS Lexicon of Named Rock Units — Result Details

Cymerig Limestone Member

Computer Code: CY Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Woolstonian Substage (OS) — Woolstonian Substage (OS)
Lithological Description: Massive or concretionary, dark blue-grey, coarsely crystalline limestone with interbedded calcareous, locally tuffaceous, mudstones.
Definition of Lower Boundary: Conformable boundary with the calcareous tuffaceous mudstones of the Gelli-grin Calcareous Ash Formation.
Definition of Upper Boundary: Gradational, passing conformably upwards into the calcareous tuffaceous mudstones of the Gelli-grin Calcareous Ash Formation.
Thickness: 0-4m
Geographical Limits: Bala and Corwen districts, North Wales.
Parent Unit: Gelli-Grin Calcareous Ash Formation (GEL)
Previous Name(s): Bala Limestone (-833)
Cymerig Limestone (-834)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Quarry, 350m westsouthwest of Gelli-grin Farm. Bassett, D A, Whittington, H B and Williams, A. 1966. 
Reference(s):
Rushton, A W A and Howells, M F. 1998. Stratigraphical framework for the Ordovician of Snowdonia and the Lleyn Peninsula. British Geological Survey Research Report, RR/99/08. 
Bancroft, B B. 1928. On the unconformity at the base of Ashgillian in the Bala district. Geological Magazine. Vol.65, 484-493. 
Elles, G L. 1922. The Bala country: its structure and rock succession. Quarterly Journal of the Geological Society of London, Vol.78, 132-175. 
Sedgwick, A. 1845. On the older Palaeozoic (Protozoic) rocks of North Wales. Quarterly Journal of the Geological Society of London. Vol.1. 5-22. 
Bassett, D A, Whittington, H B and Williams, A. 1966. The stratigraphy of the Bala district, Merionethshire. Quarterly Journal of the Geological Society of London, Vol.122, 219-271. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E136