The BGS Lexicon of Named Rock Units — Result Details

Benbulben Shale Formation

Computer Code: BBSF Preferred Map Code: BBSF
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: Mudstone, medium to dark grey, micaceous, calcareous, bioclastic, with thin to thick blue-grey, argillaceous, very fossiliferous limestones, thin calciturbidites and sandstones.
Definition of Lower Boundary: Conformable with underlying siltstone/sandstone dominated sequence of the Drumchorick Siltstone Formation and Mullaghmore Sandstone Formation (only in type area).
Definition of Upper Boundary: Conformable, rapid transition with succeeding limestone dominated sequence of the Glencar Limestone Formation, in the type area.
Thickness: c.60 - 120 metres.
Geographical Limits: Northwest Carboniferous basin of Ireland.
Parent Unit: Tyrone Group (TYRO)
Previous Name(s): Calp Shale of the Calp or Middle Limestone [Obsolete Name and Code: Use BBSF] (-1970)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Well-exposed, in stream and cliff sections, all round the lower slopes of the Dartry Mountains and the Benbulben Range, County Sligo, Ireland, centred on 10km Grid Square H 17 34. 
Reference(s):
Oswald, D H, 1955. The Carboniferous rocks between the Ox Mountains and Donegal Bay. Quarterly Journal of the Geological Society of London, Vol.111, Part 2, 167-186. 
Higgs, K, 1984. Stratigraphic palymology of the Carboniferous rocks in northwest Ireland. Bulletin of the Geological Survey of Ireland, Vol.3, No.3, 171-202. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
N32