The BGS Lexicon of Named Rock Units — Result Details

Gala Unit 4

Computer Code: GAL4 Preferred Map Code: GALA4
Status Code: Full
Age range: Rhuddanian Age (SR) — Aeronian Age (SA)
Lithological Description: Graded beds that may include wacke sandstone, siltstone and mudstone in variable proportions, interpreted as turbidites. Conglomeratic beds are a feature of this unit. Siltstone interbeds yielded fauna of the cyphus to triangulatus Biozones.
Definition of Lower Boundary: Southern faulted boundary: Gillespie Burn Fault. Stratigraphical lower boundary with underlying Moffat Shale Group (of Ordovician to Silurian age).
Definition of Upper Boundary: Northern faulted boundary: Sandhead Fault.
Thickness: c. 1500m of near vertical strata.
Geographical Limits: Mapped from Float Bay on the Rhins of Galloway (Sheet 1/3) to Peebleshire (Sheet 24 E). Correlation with Central Belt turbidites of Llandovery age in the Ards Peninsula, Northern Ireland.
Parent Unit: Gala Group (GALA)
Previous Name(s): Queensberry Grits (-1552)
Gala Group (GALA)
Intermediate Greywacke Group (-3414)
Alternative Name(s): Sinniness Or Float Bay Formation Of The Rhins Of Galloway
Sinniness Formation Of Wigtown
Stratotypes:
Reference Section  Coastal section between Stair Haven and the Mull of Sinniness, east shore of Luce Bay (Sheet 4W, [Scotland]). Barnes, in prep. 
Reference Section  Coastal section north and south of Float Bay, 4 km. WSW of Sandhead, Rhyns of Galloway (Sheet 1/3 [Scotland]). Stone, 1995. 
Reference Section  Conglomerate facies of Craigenputtock Hill, 8 km. NNE of Corsock (Sheet 9 W, [Scotland]). McMillan, A A. 2002; Phillips, 1999. 
Reference(s):
Phillips, E R. 1999. The minerology and petrology of lithic clasts from the Craigenputtock and Afton Water conglomerates, Southern Uplands, Scotland. British Geological Survey, Short Report, MPSR/99/55. 
Stone, P, 1995. Geology of the Rhins of Galloway district. Memoir of the British Geological Survey, Sheets 1 & 3 (Scotland). 
Barnes, R P, Anderson, T B and McCurry, J A . 1987. Along-strike variation in the stratigraphical and structural profile of the Southern Uplands Central Belt in Galloway and Longford Down. Journal of the Geological Society, 144, 807 - 816. 
McMillan, A A. 2002. Geology of the New Galloway and Thornhill District. 2002. Memoir of the British Geological Survey. Sheets 9W and 9E (Scotland). 
Barnes, R P, (in prep). The geology of the Kirkcowan, Wigtown and Whithorn districts. Memoir of the British Geological Survey, Sheets 4W, 4E and 2 (Scotland). 
Peach, B N and Horne, J. 1899. The Silurian Rocks of Britain, Volume 1. Scotland. Memoir of the Geological Survey of the United Kingdom. 
Lapworth, C, 1871. On the Lower Silurian rocks in the neighbourhood of Galashiels. Transactions of the Edinburgh Geological Society, 2, 46 - 58. 
Walton, E K. 1955. Silurian greywackes in Peeblesshire. Proceedings of the Royal Society of Edinburgh, B65, 327-357. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S001 S003 S004 S004 S009 S009 S016 S024 S024 N29 S015