The BGS Lexicon of Named Rock Units — Result Details

Termon River Limestone Formation

Computer Code: TRLF Preferred Map Code: TRLF
Status Code: Full
Age range: Chadian Substage (CI) — Chadian Substage (CI)
Lithological Description: Limestone, blue-grey, sparsely bioclastic, crinoidal, fine- to medium-grained containing pellets, micritised bioclasts, oncolites and ooliths, interbedded with dark grey to grey-green shale and brown, medium-grained sandstone.
Definition of Lower Boundary: Abrupt, but conformable change from deltaic facies, clastic sediments at the top of the underlying Claragh Sandstone Formation to peritidal carbonates and thin shales of the Termon River Limestone Formation.
Definition of Upper Boundary: Change from 'clean' peritidal carbonates of the Termon River Limestone Formation, to sandstones and sandy limestones of the Gortnaree Sandstone Member of the Ballyshannon Limestone Formation.
Thickness: 0 to 40m
Geographical Limits: The Kesh-Omagh area of the northwest Carboniferous basin of Ireland.
Parent Unit: Tyrone Group (TYRO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Section  North flowing stream and successive low waterfalls at the Giants Grave in Gortnaree Townland; exposes top contact and 19m of the formation. 
Reference Section  At confluence of stratotype stream and the Termon River, in south bank; base of formation and top 5m of underlying Claragh Sandstone Formation. 
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: