The BGS Lexicon of Named Rock Units — Result Details

Nant-y-Gamar Limestone Member

Computer Code: NYGL Preferred Map Code: notEntered
Status Code: Full
Age range: Asbian Substage (CR) — Asbian Substage (CR)
Lithological Description: Massive, bryozoan-rich reef limestone (bafflestone/framestone). Early Asbian buildup of trepostome bryozoan rich limestones at the margin of the North Wales Dinantian carbonate platform.
Definition of Lower Boundary: Not seen, but presumed to be a contact between massive, bryozoan-rich, reef limestones and underlying well-bedded, extensively dolomitised liestones (peloidal and skeletal grainstones) of the Llanarmon Limestone Formation
Definition of Upper Boundary: Contact between "massive reef" limestones and well bedded, extensively dolomitised limestones (peloidal and skeletal grainstones) of the Llanarmon Limestone Formation.
Thickness: At least 35m
Geographical Limits: Nant-y-Gamar, Llandudno (SH 8081)
Parent Unit: Llanarmon Limestone Formation (LNML)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Quarry at Nant-y-Gamar, Llandudno, which provides a section through the upper 35m of bryozoan-rich limestones of the Member. Bancroft et al., 1988. 
Reference(s):
Nichols, R A H, 1965. Petrology of a Lower Carboniferous bryozoan limestone and adjacent limestones in North Wales, Great Britain. Journal of Sedimentary Petrology, Vol.35, 887-899 
Bancroft, A J, Somerville, I D, and Strank, A R E, 1988. A bryozoan buildup from the Lower Carboniferous of North Wales. Lethia, Vol.21, 51-65 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable