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)
Intermediate Greywacke Group (-3414)
Gala Group (GALA)
Alternative Name(s): Sinniness Or Float Bay Formation Of The Rhins Of Galloway
Sinniness Formation Of Wigtown
Stratotypes:
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 Section  Coastal section between Stair Haven and the Mull of Sinniness, east shore of Luce Bay (Sheet 4W, [Scotland]). Barnes, in prep. 
Reference(s):
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). 
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. 
Peach, B N and Horne, J. 1899. The Silurian Rocks of Britain, Volume 1. Scotland. Memoir of the Geological Survey of the United Kingdom. 
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. 
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