The BGS Lexicon of Named Rock Units — Result Details

Gwern-Feifod Group [Obsolete Name And Code]

Computer Code: GWF Preferred Map Code: notEntered
Status Code: Index Level
Age range: Harnagian Substage (OG) — Harnagian Substage (OG)
Lithological Description: Shales and mudstones with Godor Lava passing to Godor Ash at the top of the unit.
Definition of Lower Boundary: Drawn at the base of the Gwern Feifod Group. Shales and mudstones where it rests conformably on shales with thin pyroclastic bands of the Garwallt Group.
Definition of Upper Boundary: Drawn at the conformable upward passage from the Gwern-Feifod Lava of the Gwern-Feifod Group to the Mynydd Tarn Ash Formation of the Mynydd Tarn Group.
Thickness: Not defined.
Geographical Limits: Berwyn Hills, Montgomeryshire.
Parent Unit: Not Entered (?)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Godor approximately 6kms north west of Llanrhaiadr. 
Reference(s):
Cantrill, T C, et al, 1914. Summary of Progress of the Geological Survey of Great Britain for 1914, (1915) 7. 
Wedd, C B, Smith, B, King, W B R and Wray, D A. 1929. Geology of the country around Oswestry. Memoir of the Geological Survey of Great Britain, Sheet 137. 
Williams, A and others, 1972. A correlation of Ordivician rocks in the British Isles. Geological Society of London Special Report No.3. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable