The BGS Lexicon of Named Rock Units — Result Details

Gallagh Bridge Formation

Computer Code: GGH Preferred Map Code: GGH
Status Code: Full
Age range: Guadalupian Epoch (PUG) — Lopingian Epoch (PUL)
Lithological Description: Sandstone, red, fine-to-medium-grained, dolomite cement; thin layers of red siltstone and mudstone, brown mudstone up to 15%.
Definition of Lower Boundary: Sharp contact with white dolomitic limestone of the underlying Magnesian Limestone Formation.
Definition of Upper Boundary: Gradational but rapid decrease in cemented sandstone and increase of red mudstone and siltstones in the overlying Drumderg House Formation [formerly known as Permian Upper Marls].
Thickness: 26.9 - 50.3m [88 - 165ft]
Geographical Limits: Sub-surface on northwest shore of Lough Neagh.
Parent Unit: Belfast Group (BELF)
Previous Name(s): Permian Upper Sandstone (-4061)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Annaghmore-1 Borehole. GSNI Borehole Database Number 94SE/1 [3177-3265ft--968.3-995.2m] Based on cutting samples at 10ft intervals of which a split sample is stored with the Geological Survey of Northern Ireland. 
Reference(s):
Naylor, D, Philcox, M E and Clayton, G. 2003. Annaghmore-1 and Ballynamullan-1 wells, Larne-Lough Neagh Basin, Northern Ireland. Irish Journal of Earth Sciences, Vol.21, 47-69. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable