The BGS Lexicon of Named Rock Units — Result Details

Polglaze Formation

Computer Code: POLG Preferred Map Code: Polg
Status Code: Full
Age range: Early Devonian Epoch (DL) — Early Devonian Epoch (DL)
Lithological Description: A dark grey, slatey cleaved mudstone, which has a marked absence of coarser lithologies, and showing low grade (anchizone) regional metamorphism.
Definition of Lower Boundary: Faulted against the Portscatho Formation, comprising predominantly turbiditic sandstone beds.
Definition of Upper Boundary: Faulted against the Hallane Formation, seen as a mudstone with siltstone and limestone.
Thickness: Unknown, as obscured by complex folding, but probably at least 500m.
Geographical Limits: Mevagissey Sheet 353 (England and Wales), but is known to extend northwards onto the Bodmin and St. Austell Sheet (347), for which no modern mapping is available.
Parent Unit: Meadfoot Group (MDT)
Previous Name(s): Meadfoot Beds (-76)
Alternative Name(s): none recorded or not applicable
Partial Type Section  Coastal section between Polrudden Cove and Polgwyn Beach. 
Reid, C, 1907. Geology of the country around Mevagissey. Memoir of the Geological Survey of Great Britain. (London: HMSO.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E353 E354