The BGS Lexicon of Named Rock Units — Result Details

Polzeath Slate Formation

Computer Code: PZS Preferred Map Code: PzS
Status Code: Pending Upgrade
Age range: Frasnian Age (DR) — Famennian Age (DA)
Lithological Description: Cleaved purple mudstone with pale green and grey beds and laminae, and thin sandstone and laminated siltstone horizons. Thicker beds of green mudstone occur in association with dark grey mudstone, which is sporadically fossiliferous.
Definition of Lower Boundary: Faulted where seen on coast, inland rests conformably on Harbour Cove Slate Formation.
Definition of Upper Boundary: Not seen.
Thickness: Estimates vary between 240-320m.
Geographical Limits: Padstow Bay to west of St Tudy, north Cornwall.
Parent Unit: Not Available (!)
Previous Name(s): Upper Devonian Purple And Green Slates (-475)
Alternative Name(s): Polzeath Slates
Stratotypes:
Type Section  Cliffs between Daymer Bay, Trebetherick and the Greenaway, Polzeath. Beese, A P, 1984. 
Reference(s):
Beese, A P, 1984. Stratigraphy of the Upper Devonian argillite succession in north Cornwall. Geological Magazine, Vol.121, 61-69. 
Selwood, E B, Thomas, J M, Williams, B J, Clayton, R, Durning, B, Smith, O and Warr, L N, 1998. Geology of the country around Trevose Head and Camelford. Memoir of the British Geological Survey, sheets 335 and 336 (England and Wales). 
Gauss, G A and House, M R, 1972. The Devonian successions in the Padstow area, north Cornwall. Journal of the Geological Society of London, Vol.128, 151-172. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E336