| Computer Code: |
FW |
Preferred Map Code: |
FwF |
| Status Code: |
Full |
| 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 X. 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 |
