The BGS Lexicon of Named Rock Units — Result Details

Nant Y Gledryd Member

Computer Code: NYGD Preferred Map Code: NyG
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Crystal-lithic tuffs with variable characteristics, locally strongly welded towards the top.
Definition of Lower Boundary: Oxidised and reddened top of the rhyodacite lavas of the Foel Ddu Rhyodacite Formtion.
Definition of Upper Boundary: Overlain by coarse crystal-lithic tuffs of the Bodgadle Member, or by volcanoclastic sediments of the Yoke House Formation.
Thickness: 200m
Geographical Limits: Pwllheli area, northwest Wales.
Parent Unit: Carneddol Rhyolitic Tuff Formation (CRTU)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Nant y Gledryd. 
Reference(s):
Young, T P, Gibbons, W and McCarroll, D. 2002. Geology of the country around Pwllheli. Memoir of the British Geological Survey, Sheet 134 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E134