The BGS Lexicon of Named Rock Units — Result Details

Fernagh Formation

Computer Code: FRNA Preferred Map Code: FRN
Status Code: Full
Age range: Ordovician Period (O) — Ordovician Period (O)
Lithological Description: Pale buff, pinkish and green aphanitic sometimes flow banded and auto-brecciated lavas and partly intrusive felsite.
Definition of Lower Boundary: Where seen, intrusive contact with structurally underlying Tonalite intrusion.
Definition of Upper Boundary: Not exposed but most likely to be conformable with overlying tuffs and lava of Tyrone Volcanic Group.
Thickness: Max 300m
Geographical Limits: Fernagh, Brackagh South and Cashel Rock, County Tyrone, Northern Ireland.
Parent Unit: Tyrone Volcanic Group (TVG)
Previous Name(s): Fernagh Andesite And Dacite Formation [Obsolete Name And Code: Use FRNA] (FADF)
Fernagh Andesite And Dacite Formation (Obsolete Name And Code: Use FRNA) (-3408)
Replaced By Fernagh Formation (*515)
Alternative Name(s): none recorded or not applicable
Type Area  Fernagh Townland, County Tyrone, Northern Ireland. 
Geological Survey of Northern Ireland 1979. Pomeroy, sheet 34, solid, 1:50 000. [Southampton, Ordnance Survey for Institute of Geological Sciences.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used: