The BGS Lexicon of Named Rock Units — Result Details

Powgavie Clay Member

Computer Code: PGCL Preferred Map Code: notEntered
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Marine clay containing sub-angular ice-rafted clasts (dropstones) characterized by graded units from 2cm to 10cm thick consisting of a thin basal layer of pale coloured silt or sand passing up into dark brownish grey clay. Sporadic laminae and thicker beds are stained black by sulphide. The deposit is considered to be prodeltaic in origin.
Definition of Lower Boundary: The relationship of the Powgavie Clay to the Errol Clay Formation is not clearly demonstrable at any known locality. At the type section the member rests unconformably on glaciofluvial sand and gravel. This relationship is assumed to have come about by mass movement on the sea floor causing removal of the Errol Clay before deposition of this member.
Definition of Upper Boundary: Diachronous transitional top with and passing laterally into the Culfargie Sand Member.
Thickness: 20m known at Powgavie.
Geographical Limits: Catchment of the River Tay east of Perth adjacent to the Tay estuary.
Parent Unit: Forth Clay Formation (FOCL)
Previous Name(s): Powgavie Clay (-2369)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Powgarvie B Borehole, BGS Ref. NO22NE/31, from 14.73m to 35.10m depth; Carse of Gowrie, west of Perth. Paterson et al., 1981. 
Reference(s):
Paterson, I B, Armstrong, M and Browne, M A E. 1981. Quaternary estuarine deposits in the Tay-Earn area, Scotland. Report of the Institute of Geological Sciences, No.81/7. 
Armstrong, M, Paterson, I B and Browne, M A E, 1985. Geology of the Perth and Dundee district. Memoir of the British Geological Survey, Sheets 48W, 48E and 49 (Scotland). 108pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S048