The BGS Lexicon of Named Rock Units — Result Details

St Fergus Silt Formation

Computer Code: SFSI Preferred Map Code: SF
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: A dark grey, silty clay with laminae of sand and well dispersed gravel dropstone clasts, containing boreal to boreal arctic marine microfossils; interpreted as a glaciomarine deposit.
Definition of Lower Boundary: A sharp, undulating, unconformable contact with underlying till, comprising grey, pebbly clay diamicton, yellowish brown gravelly clayey sand diamicton, and reddish brown gravelly silty sandy clay diamicton.
Definition of Upper Boundary: A gradational contact with overlying organic silts and clays, interpreted as lacustrine alluvium.
Thickness: To 16m
Geographical Limits: Buchan, northeast Scotland, on Sheets 97 (Fraserbugh) amd 87E (Peterhead).
Parent Unit: British Coastal Deposits Group (COAS)
Previous Name(s): St Fergus Silts (-1176)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  BGS registered borehole NK15SW/1, 1.9 - 17.9 m depth. McMillan and Aitken, 1981; Peacock, 1999; Merritt et al, 2000, 2003. 
Reference(s):
Merritt, J W, Auton, C A, Connell, E R, Hall, A M and Peacock, J D. 2003. The Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, Sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland) 
Hall, A M and Jarvis, J. 1989 A preliminary report on the Late Devensian glaciomarine deposits around St. Fergus, Grampian Region. Quaternary Newsletter, Vol.59, 5-7. 
McMillan, A A and Aitken, A M. 1981. The sand and gravel resources of the country west of Peterhead, Grampian Region. Description of 1:25 000 sheet NK 04 and parts of NJ 94, 95 and NK 05, 14, and 15. Mineral Assessment Report of the Institute of Geological Sciences, No 58. 
Merritt, J W, Connell, E R and Bridgland, D R (editors). 2000. The Quaternary of the Banffshire Coast and Buchan; Field Guide. (London: Quaternary Research Association.) 
Peacock, J D. 1999. The pre-Windermere Interstadial (late Devensian) raised marine strata of eastern Scotland and their macrofauna: a review. Quaternary Science Reviews, Vol.18, 1655-1679. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S097 S087