The BGS Lexicon of Named Rock Units — Result Details

Glyn Formation

Computer Code: GYN Preferred Map Code: GyN
Status Code: Full
Age range: Rawtheyan Stage (OW) — Hirnantian Age (OH)
Lithological Description: Fine- to coarse-grained sandstones and thin siltstones; a locally developed limestone member (Glyn Limestone) at base on Mynydd Fron Frys.
Definition of Lower Boundary: Top of underlying micaceous siltstones and mudstones of the Dolhir or Cyrn-y-Brain Beds.
Definition of Upper Boundary: Overlain by shales and slates of the Fron Frys Formation.
Thickness: 21-70m
Geographical Limits: Glyn Ceiriog and Llanelidan-Eglwyseg area of east Wales.
Parent Unit: Not Applicable (-)
Previous Name(s): Glyn Grit (-4077)
Glyn Grit And Limestone [Obsolete Name And Code: See GYN] (GLG)
Alternative Name(s): Corwen Grit Member
Stratotypes:
Type Area  Type area around Glyn Ceiriog. Section on Mynydd Fron Frys, south east of Glyn Ceiriog. 
Reference(s):
Hiller, A, 1981. The Ashgill rock of the Glyn Ceiriog district, north Wales. Geological Journal, Vol.16, p.181-200. 
Groom, T, Lake, P, 1908. Glyn Grit. Quarterly Journal of the Geological Society, Vol.64. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E121 E120 E137