The BGS Lexicon of Named Rock Units — Result Details

Green Croft Till Member

Computer Code: GCTI Preferred Map Code: GCT
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Mainly dark reddish brown (Munsell Soil) pebbly silt diamicton with interbeds of subglacially sheared pebbly sand, silt and clay. The diamicton contains clasts of igneous and metamorphic rock types from the Lake District together with some red sandstone and coal.
Definition of Lower Boundary: Generally sharp, planar, glacitectonic, unconformable contact with dark brown clay of the Whinneyhill Coppice Clay Member of the Aikbank Farm Glacigenic Formation.
Definition of Upper Boundary: Sharp, unconformable contact with overlying reddish brown clay and silt of the Holmeside Clay Member of the Aikbank Farm Glacigenic Formation. Taken at the top of the uppermost bed of diamicton in the sequence.
Thickness: To 10m
Geographical Limits: Lower Wasdale, West Cumbria, inland of the limit of ice of the Irish Sea Ice Stream during the "Gosforth Oscillation".
Parent Unit: Aikbank Farm Glacigenic Formation (AIK)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  BGS registered borehole SD19NW11 (Aikbank Farm Borehole 1), from 25.34 to 35.60m depth. Nirex, 1997. 
Type Section  BGS registered borehole SD19NW12 (Aikbank Farm Borehole 2), from 27.73 to 33.69m depth. Nirex, 1997. 
Reference(s):
Merritt, J W and Auton, C A. 1997. Quaternary lithostratigraphy of the Sellafield district. Nirex Science Report SA/97/045 (Issue 2.0). [Report prepared for UK Nirex Ltd. 69pp, 5 tables, 20 figures, 14 enclosures and one appendix.] 
Merrit, J W and Auton, C A. 2000. An outline of the lithostratigraphy and depositional history of Quaternary deposits in the Sellafield district, west Cumbria. Proceedings of the Yorkshire Geological Society, Vol.53, 129-154 
Akhurst, M C, Chadwick, R A, Holliday, D W, McCormac, M, McMillan, A A, Millward, D, Young, B, Ambrose, K, Auton, C A, Barclay, W J, Barnes, R P, Beddoe-Stephens, B, James, J C W, Johnson, H, Jones, N S, Glover, B W, Hawkins, M P, Kimbell, G S, MacPherson, K A T, Merritt, J W, Milodowski, A E, Riley, N J, Robins, N S, Stone, P and Wingfield, R T R. 1997. The geology of the west Cumbria district. Memoir of the British Geological Survey, Sheets 28, 37 and 47 (England and Wales). 138pp. 
Huddart, D. 1991. The glacial history and glacial deposits of the north and west Cumbrian lowlands, 151-167 in Ehlers, J, Gibbard, P L and Rose, J (editors), Glacial deposits in Great Britain and Ireland. [London: Balkema.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable