The BGS Lexicon of Named Rock Units — Result Details

Portfield Formation

Computer Code: PFLD Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Hirnantian Age (OH) — Hirnantian Age (OH)
Lithological Description: Interbedded dark grey carbonaceous mudstones [Cuckoo Shale Member; Scotchwell Shale Member] and well-sorted, fine-grained, grey and buff sandstones [Cethings Sandstone Member]. Local conglomerates at, or near, the base of the Formation.
Definition of Lower Boundary: Apparently conformable on the underlying Slade and Redhill Formation, but contact nowhere seen.
Definition of Upper Boundary: Conformably and gradationally overlain by the Haverford Mudstone Formation.
Thickness: At least 65m
Geographical Limits: none recorded or not applicable
Parent Unit: Not Available (!)
Previous Name(s): Basement Beds (-3812)
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Cocks, L R M and Price, D. 1975. The biostratigraphy of the Upper Ordovician and Lower Silurian of south-west Dyfed, with comments on the Hirnantia fauna. Palaeontology, Vol.18, 703-724. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable