The BGS Lexicon of Named Rock Units — Result Details

Glyn Gower Siltstones Member

Computer Code: GYG Preferred Map Code: GyG
Status Code: Pending Upgrade
Age range: Soudleyan Substage (OY) — Soudleyan Substage (OY)
Lithological Description: Laminated siltstones and fine-grained sandstones with subordinate mudstones and rare thin tuffs.
Definition of Lower Boundary: Conformable and gradational with mudstones of the Ceiswyn Formation, generally taken at the top of the Cefn Gwyn Tuff where the latter is present.
Definition of Upper Boundary: Conformable and gradational with mudstones of the Ceiswyn Formation, but generally taken at the base of the overlying Frondderw Tuff, where the latter is present.
Thickness: 130m to 150m.
Geographical Limits: Corwen and Bala districts.
Parent Unit: Ceiswyn Formation (CSW)
Previous Name(s): Glyn Gower Formation (-2838)
Glyn Gower Siltstones [Obsolete Code: Use GYG] (GLS)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Lower reaches of the Glyn Gower valley, 1km southeast of Llangower village. Elles, 1922. 
Partial Type Section  Hill top, northeast of the Glyn Gower valley. Bassett, D A, Whittington, H B and Williams, A. 1966 
Reference(s):
Elles, G L. 1922. The Bala country: its structure and rock succession. Quarterly Journal of the Geological Society of London, Vol.78, 132-175. 
Bessett, D A, Whittington, H B and Williams, A. 1966. The stratigraphy of the Bala district, Merionethshire. Quarterly Journal of the Geological Society, London, Vol.122, 219-271. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E120 E136