The BGS Lexicon of Named Rock Units — Result Details

Felin-Wen Formation

Computer Code: FW Preferred Map Code: FwF
Status Code: Pending Upgrade
Age range: Llanvirn Series (OE) — Llanvirn Series (OE)
Lithological Description: Silt-laminated mudstone with sparse, scatterd thin sandstone or calcareous sandstone beds.
Definition of Lower Boundary: Taken at the sharp incoming of silt-laminated mudstone of the Felin-wen Formation above the hemipelagic laminated and burrowed mudstone of the Aber Mawr Shales Formation. Base not observed in the Newcastle Emlyn district.
Definition of Upper Boundary: Taken at the sharp incoming of tuff or tuffaceous sandstone, or locally calcareous sandstone and shelly limestone of the overlying Asaphus Ash Formation.
Thickness: c.70m
Geographical Limits: Newcastle Emlyn district, may be a synonym, in part or in full, of the Murchisoni Beds of the Carmarthen district, but further work is needed.
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): Murchisoni Beds
Stratotypes:
Partial Type Section  Section in the lane leading up to Merlin's Grove Farm. 10m exposed in the lower part of the formation, neither base nor top seen. 
Reference(s):
Schofield, D I and Wilby, P R. In prep. Geology of the Newcastle Emlyn district - a brief explanation of the geological map. Sheet explanation of the British Geological Survey. 1:50 000 Sheet 211 Newcastle Emlyn (England and Wales). 
Strahan, A, Cantrill, T C, Dixon, E E L and Thomas, H H. 1909. The Geology of the South Wales coalfield. Part 10. The country around Carmarthen. Memoir of the Geological Survey of England and Wales. [London: HMSO.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable