The BGS Lexicon of Named Rock Units — Result Details
Crossbrae Till Formation
| Computer Code: | CBTIL | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Wolstonian Stage (QO) — Wolstonian Stage (QO) | ||
| Lithological Description: | Dominantly brown/dark brown, very stiff, weakly calcareous, matrix supported, gravelly slightly clayey silty sand diamicton. Clast lithologies are dominated by quartzite/psammite and red brown Devonian sandstones, with less common pelitic/semipelitic metasediments, felsite, grey granite and mafic igneous rocks. Clasts are typically subangular - subrounded (with the pelitic metasedimentary rocks commonly striated). Clast fabrics indicate glacial transport from the northwest. Interpreted as a subglacial till. | ||
| Definition of Lower Boundary: | A sharp, planar, unconformity on Devonian red-brown pebbly sandstones. | ||
| Definition of Upper Boundary: | A sharp, planar, subhorizontal surface overlain by periglacial diamictons of the Crossbrae Gelifluctate Bed. The Crossbrae Till Formation is believed to be locally overlain by the Crossbrae Farm Peat Bed. | ||
| Thickness: | Up to 0.7m observed | ||
| Geographical Limits: | Buchan, northeast Scotland. The formation is curently only known from the vicinity of Crossbrae Farm, Turriff on Sheet 86E (Turriff). The unit may be regionally significant and present locally across northeast Scotland. | ||
| Parent Unit: | East Grampian (Albion) Glacigenic Subgroup (EGAG) | ||
| Previous Name(s): | Crossbrae Till Formation
(CBTIL)
Crossbrae Till Formation (CBTIL) Lower Diamicton [Obsolete Name and Code: Use CBTIL] (-4525) Till with northwest-southeast fabric [Obsolete Name and Code: Use CBTIL] (-114) |
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| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Partial Type Section | Temporary drainage pipe excavation (Site A, pit 2), near Crossbrae Farm, 3km northeast of Turriff, Buchan, northeast Scotland. Whittington et al., 1998. | ||
| Partial Type Section | Temporary drainage pipe excavation (Site A, pit 1), near Crossbrae Farm, 3km northeast of Turriff, Buchan, northeast Scotland. Whittington et al., 1998. | ||
| Reference(s): | |||
| Hall, A M and Connell, E R. 1991. The glacial deposits of Buchan, northeast Scotland. 129-136 in Ehlers, J, Gibbard, P L and Rose, J (editors), Glacial Deposits in Great Britain and Ireland. (Rotterdam: Balkema.) | |||
| 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.) | |||
| Whittington, G. 1994. Bruckenthalia spicufolia (Salisb.). Reichemb. (Ericaceae), in the Late Quaternary of western Europe. Quaternary Science Reviews, Vol.13, 761-768. | |||
| Whittington, G, Connell, E R, Coope, G R, Edwards, K J, Hall, A M, Hulme, P D and Jarvis, J. 1998. Devensian organic interstadial deposits and ice sheet extent in Buchan, Scotland. Journal of Quaternary Science, Vol.13, 309-324. | |||
| Hall, A M (Editor). 1984. Buchan Field Guide. Quaternary Research Association, Cambridge, 120pp. | |||
| 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) | |||
| Connell, E R and Hall, A M. 1987. The periglacial history of Buchan, Scotland. 277-285 in Boardman, J (Editor), Periglacial Processes and Landforms in Britain and Ireland. Periglacial processes in Britain and Ireland. Cambridge University Press, Cambridge. | |||
| Sutherland, D G. 1999. Scotland. 99-114 in Bowen D Q (Editor), A revised correlation of Quaternary deposits in the British Isles. Special Report of The Geological Society of London, No.23. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| none recorded or not applicable | |||