The BGS Lexicon of Named Rock Units — Result Details

Gortnaree Sandstone Member

Computer Code: GESM Preferred Map Code: GESM
Status Code: Full
Age range: Chadian Substage (CI) — Chadian Substage (CI)
Lithological Description: Sandstone, medium grey, weathering to brown rottenstone, fine- to medium-grained, calcareous, interbedded with pale blue-grey, variably arenaceous, bioclastic, crinoidal packstone with pellets.
Definition of Lower Boundary: Conformable and abrupt; calcareous sandstones and very sandy limestones at base of member rest on 0.16m of calcareous silty shale and argillaceous limestone at top of Termon River Limestone Formation.
Definition of Upper Boundary: Conformable and gradational; decreasing arenaceous content upwards into normal Ballyshannon Limestone Formation. Boundary located at base of blue-grey bioclastic packstones.
Thickness: 5.3m
Geographical Limits: Kesh-Omagh area of the northwest Carboniferous basin of Ireland.
Parent Unit: Ballyshannon Limestone Formation (BAL)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Waterfall section and river exposures at the Giants Grave, Gortnaree Townland. 
Type Area  First rock ridge lying south of the International Border marked by the Termon River from Rushinbane Townland to the Giants Grave section. 
Reference(s):
Mitchell, W I, Johnston, T P and Legg, I C. 2004. Geology of the country around Kesh, Co. Fermanagh and Omagh, Co. Tyrone. Geological Sheets 32 and part of 31 (Kesh) and 33 (Omagh). Geological Survey of Northern Ireland. Technical Report GSNI 04/1. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
N32