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 And Limestone [Obsolete Name And Code: See GYN] (GLG)
Glyn Grit (-4077)
Alternative Name(s): Corwen Grit Member
Type Area  Type area around Glyn Ceiriog. Section on Mynydd Fron Frys, south east of Glyn Ceiriog. 
Groom, T, Lake, P, 1908. Glyn Grit. Quarterly Journal of the Geological Society, Vol.64. 
Hiller, A, 1981. The Ashgill rock of the Glyn Ceiriog district, north Wales. Geological Journal, Vol.16, p.181-200. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E121 E120 E137