The BGS Lexicon of Named Rock Units — Result Details

Great Conglomerate Formation

Computer Code: GCGL Preferred Map Code: GCGL
Status Code: Full
Age range: Silurian Period (S) — Devonian Period (D)
Lithological Description: Red and purple conglomerates, fine- to coarse-grained, chiefly composed of rounded greywacke pebbles and boulders in a red-brown sandstone matrix with some interbedded pebbly sandstones, thin red-brown siltstones and mudstones.
Definition of Lower Boundary: Unconformable on the Silurian and Ordovician rocks of the Southern Uplands terrane.
Definition of Upper Boundary: Not generally seen as faulted against the Devono-Carboniferous in the Dunbar area. In the St Abb's area, it is overlain by Eyemouth Volcanic Formation.
Thickness: 120m to greater than 350m
Geographical Limits: The Southern Uplands Terrane, Scotland, bounded by the Southern Uplands Fault to the north-west in the Dunbar - Lauder - St Abb's area,
Parent Unit: Reston Group (REST)
Previous Name(s): Lower Or Great Conglomerate (-2817)
Great Conglomerate (-2197)
Pre-Volcanic Sedimentary Rocks At Bell Hill (-2198)
Lauder Conglomerate (*652)
Alternative Name(s): Lauder Conglomerate
Stratotypes:
Type Area  Back Water, 10km south of Dunbar. Davies et al, 1986. 
Partial Type Section  Base is unconformable on Silurian rocks on cliffs south of Bell Hill, the top is seen along the base of White Heugh where sandstones and siltstones are overlain by lavas of the Eyemouth Volcanic Formation. The unit is partly faulted along the shore south of St Abb's Head. Greig, 1988. 
Reference(s):
Greig, D C. 1988. Geology of the Eyemouth district. Memoir of the British Geological Survey, Sheet 34 (Scotland). 
McAdam, A D and Tulloch, W, 1985. Geology of the Haddington district. Memoir of the Geological Survey, sheet 33W (Scotland). 
Clough, C T, Barrow, G, Crampton, C B, Maufe, H B, Anderson, E M and Bailey, E B . 1910. The geology of East Lothian (2nd edition). Memoir of the Geological Survey, Scotland, Sheets 33 and parts of 34 and 41. 
Davies, A, McAdam, A D and Cameron, I B. 1986. Geology of the Dunbar district. Memoir of the British Geological Survey, Sheet 33E and part of Sheet 41 (Scotland). 
Howell, H H, Geikie, A and Young, J. 1866. The geology of East Lothian including parts of the counties of Edinburgh and Berwick (Maps 33, 34 and 41). Memoir of the Geological Survey of Great Britain. 
Browne, M A E, Smith, R A and Aitken, A M. 2001. A lithostratigraphical framework for the Devonian (Old Red Sandstone) rocks of Scotland south of a line from Fort William to Aberdeen. Version 3. British Geological Survey Research Report RR/01/04. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S033 S025 S025 S025 S033 S034