The BGS Lexicon of Named Rock Units — Result Details

Whitsand Bay Formation

Computer Code: WTD Preferred Map Code: Wtd
Status Code: Full
Age range: Lochkovian Age (DO) — Pragian Age (DP)
Lithological Description: Purple and green slaty mudstone and siltstone with thin to medium beds of grey green sandstones and sporadic packets of pale grey quartzite sandstone beds. Local mottling and blebbing due to bioturbation, dispersed sedimentary clasts and volcanic detritus.
Definition of Lower Boundary: Base not seen on Sheet 348 or elsewhere in southwest England.
Definition of Upper Boundary: Upper part comprises pale grey-green silty mudstone with fine-grained sandstone streaks, lenses, thick/thin beds of sandstone and lenticular quartzite beds. Boundary with Bovisand Formation marked by colour change to dark grey above. Above the boundary bioturbation, bioclasts and sandstone beds with load casting and cross lamination are progressively more common.
Thickness: c.3300m
Geographical Limits: Sheet 348 (not mapped elsewhere).
Parent Unit: Dartmouth Group (DRTM)
Previous Name(s): Dartmouth Slates [Obsolete Name And Code] (DTMS)
Dartmouth Group (DRTM)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Cliff sections between Western Gear (near Rame Head) and Crowstone Cliff (near Freathy). 
Reference(s):
Sedgwick, A, 1852. On the slate rocks of Devon and Cornwall, Quarterly Journal of the Geological Society, Vol.8, 1-19. 
Ussher, W A E, 1891. The Devonian Rocks as described by De La Beche, etc. Transactions of the Royal Geological Society of Cornwall, Vol.II, 273-326. 
Leveridge B E, Holder, M T, Goode, A J J, Scrivener R C, Jones N S and Merriman, R J. 2002. Geology of the Plymouth and south-east Cornwall area. Memoir of the British Geological Survey, Sheet 348 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E348