The BGS Lexicon of Named Rock Units — Result Details

Ettrick Group

Computer Code: ETRK Preferred Map Code: ETRK
Status Code: Full
Age range: Llandovery Epoch (SL) — Llandovery Epoch (SL)
Lithological Description: Interbedded turbidite (wacke) sandstone and mudstone/siltstone. Sandstone typically fine- to medium-grained but ranging from very fine- to coarse-grained; generally medium- to very thick-bedded (commonly up to 2m) over thicknesses of tens of metres interspersed with units up to a few metres very thin to thin-bedded. Units of coarse-grained, massive sandstone tens of metres in thickness occur locally in parts of the group. Except in the latter, interbedded siltstone or silty mudstone is generally present in thin to medium beds. A basal massive siltstone unit a few metres thick at transition from underlying Moffat Shale Group. Sandstone and siltstone are typically greenish grey when fresh, pale brown weathering. Distinguished from the Gala Group to the north by the well-bedded character and relatively high proportion of interbedded mudstone. Other distinguishing factors include the younger age range, abundant garnet in coarse-grained sandstone and relatively low Sr and Ni content in whole rock sandstone composition. Distinguished from Hawick Group to the south by the common occurrence of thick to very thick beds of sandstone, abundant garnet in coarse-grained sandstone and paler, less pervasive weathering reflecting relatively low carbonate content of the sandstone.
Definition of Lower Boundary: Conformable sedimentary contact with the Moffat Shale Group.
Definition of Upper Boundary: Faulted, none preserved.
Thickness: Uncertain, likely to be several km.
Geographical Limits: Southern uplands. Scotland.
Parent Unit: Not Applicable (-)
Previous Name(s): Queensbury Formation (-4033)
Queensbury Grits (-4034)
Hawick Group (HWK)
Garnetiferous Group (-1534)
Hawick Rocks (-3383)
Buckholm Formation (-237)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Hills south of the Moffat Water and in the catchment of the Ettrick Water between Moffat and Ettrickbridge, Dumfries and Galloway and Scottish Borders regions, Scotland. Webb et al., 1993, Kassi and Weir, 1993 
Reference(s):
Webb, B C, Rushton, A W A and White, D E. 1993. Moffatdale and the upper Ettrick valley. Description of the solid geology of parts of 1:25000 sheets NT10, 11, 20 and 21. Classical Areas of British Geology. (London: British Geological Survey, HMSO.) 
Peach, B N and Horne, J. 1899. The Silurian Rocks of Britain, Volume 1. Scotland. Memoir of the Geological Survey of the United Kingdom. 
British Geological Survey. 1991. Moffatdale. Solid Geology. 1:25 000. Classical areas of British geology. (Keyworth, Nottingham: British Geological Survey). 
Kassi, A M and Weir, J A. 1993. Depositional and geotectonic history of the Gala area, eastern Southern Uplands, Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences, Vol.84, 161-173. 
Walton, E K. 1955. Silurian greywackes in Peeblesshire. Proceedings of the Royal Society of Edinburgh, B65, 327-357. 
White, D E, Barron, H F, Barnes, R P and Lintern, B C. 1991. Biostratigraphy of late Llandovery (Telychian) and Wenlock turbiditic sequences in the SW Southern Uplands, Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences, Vol.82, 297-322. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable