The BGS Lexicon of Named Rock Units — Result Details

Omagh Sandstone Group

Computer Code: OMSG Preferred Map Code: OMSG
Status Code: Full
Age range: Courceyan Substage (CF) — Courceyan Substage (CF)
Lithological Description: Predominantly clastic sediments; at the base are red-bed conglomerates and coarse sandstones, overlain by deltaic sandstones, siltstones and carbonaceous shales; highest beds are dark grey peritidal carbonates, serpulid limestones and shales.
Definition of Lower Boundary: Unconformity on Dalradian Supergroup metamorphic rocks.
Definition of Upper Boundary: Overlain unconformably by clastic sediments of the Claragh Sandstone Formation.
Thickness: 200 - 600m
Geographical Limits: The Kesh-Omagh area of the northwest Carboniferous basin in Ireland.
Parent Unit: Not Entered (?)
Previous Name(s): Lower Carboniferous Sandstone And Shale (-3597)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Cool River section 1.45km SSW of Dunnaree Hill. Downstream (E) of Cool Bridge are grey sandstones, siltstones and occasional peritidal limestones. Upstream (W) of Cool Bridge are fossiliferous dark grey shales,laminated carbonates and serpulid limestones. 
Reference Section  Killyclogher Burn, north east of Omagh, exposes the basal unconformity and the basal c.100m of red-bed clastics. Downstream "in" Omagh outskirts are deltaic sandstones, siltstone and shales. (Defined on basis of GSNI mapping). 
Reference Section  Glendurragh River, 600m north of Lack, County Fermanagh. Exposes basal unconformity and c.60-70m of lowest strata (defined on basis of GSNI mapping). 
Reference(s):
Simpson, I M, 1954. The Lower Carboniferous stratigraphy of the Omagh Syncline, Northern Ireland. Quarterly Journal of the Geological Society of London, Vol.110, 391-408. 
Wilkinson, S B and Kilroe, J R, 1886. Explanatory Memoir to accompany Sheet 33 of the map of the Geological Survey of Ireland including the district around Omagh, Fintona and Irvinestown. Her Majesty's Stationery Office, Dublin and London. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable