The BGS Lexicon of Named Rock Units — Result Details

Fron Frys Formation

Computer Code: FFR Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Llandovery Epoch (SL) — Llandovery Epoch (SL)
Lithological Description: Mudstones and siltstones.
Definition of Lower Boundary: Overlies mudstones of the Laundry Mudstones Formation.
Definition of Upper Boundary: Overlain by pale green-grey mudstones of the Dolgau Mudstones Formation.
Thickness: 25m
Geographical Limits: Central and northeast Wales.
Parent Unit: Not Applicable (-)
Previous Name(s): Fron Frys Slates (-3401)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Along part of the Nant Llechog, about 2km southeast of Corwen. 
Reference(s):
Lake, P and Groom, T. 1893. The Llandovery and associated rocks of the neighbourhood of Corwen. Quarterly Journal of the Geological Society, London. Vol.149, 426-440. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E136 E120 E137 E121