The BGS Lexicon of Named Rock Units — Result Details

Ulster White Limestone Group

Computer Code: UWLF Preferred Map Code: notEntered
Status Code: Full
Age range: Santonian Age (KS) — Maastrichtian Age (KM)
Lithological Description: Principally limestones (hardened chalks) with subordinate flint, marl, sponge bed, hardground, conglomeratic and fossil acme bands, with glauconite grains where formations become condensed over structural highs.
Definition of Lower Boundary: The base rests disconformably on various members of the Hibernian Greensands Formation and oversteps (unconformable) onto older pre-Cretaceous rocks. Internal overstep within the group, principally at the level of the Post-Larry Bane White Limestone Subgroup (informal term defined withiin this Lexicon entry), places successively higher formations at the base of the group over structural highs at the margins of the principal basins
Definition of Upper Boundary: Eroded contact where the group is overlain by the Palaeogene Antrim Basalts or Quaternary deposits.
Thickness: Highly variable dependant on the position within structurally controlled basins (environments) of which five were named by Fletcher (1977) as the Hebridean Basin (presumably incorporating his Londonderry Shelf and North Antrim Basin), the Highland Border (also termed the Dalradian Massif), the Midland Valley (usually termed the East Antrim Basin) and the Southern Uplands. Up to 150m+ of "White Limestone" was encountered in the Aughrimderg Borehole [H 880 685] (Wilson , 1972, p 56) but the thickest and most complete development at outcrop is found on the North Antrim coast where 120m of beds are present, although not at any one locality. The Geological Society Special Report on the Cretaceous (Rawson et al., 1978) gives a value of 130m.
Geographical Limits: Northern Ireland. Fullest development in the North Antrim Basin with significant successions in the Midland Valley (East Antrim Basin) and the Southern Uplands as defined in Fletcher (1977).
Parent Unit: Not Applicable (-)
Previous Name(s): White Limestone Formation (WHL)
Upper Chalk (White Limestone) And Lower Chalk (Glauconitic Chalk) (-596)
White Limestone (WLM)
Upper Chalk (-241)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Numerous widespread exposures of the constituent formations within Northern Ireland, with no one site containing all of the stratigraphical elements included within the group. 
Reference(s):
Reid, R E H. 1958. Remarks on the Upper Cretaceous Hexatinellida of County Antrim. The Irish Naturalists? Journal, Vol. 12, 263-268. 
Portlock, J E, 1843. Report on the Geology of the County of Londonderry and parts of Tyrone and Fermanagh. HMSO, Dublin. 
Tate, R. 1865. On the correlation of the Cretaceous formations of north-east Ireland. Quarterly Journal of the Geological Society of London, Vol. 21, 15-44. 
Griffith, A E and Wilson, H E. 1982. Geology of the country around Carrickfergus and Bangor. Memoir of the Geological Survey of Northern Ireland. Sheet 29 (Northern Ireland). 
Hancock, J M. 1961. The Cretaceous System in Northern Ireland. Quarterly Journal of the Geological Society of London, Vol. 117, 11-36. 
Fletcher, T P. 1977. Lithostratigraphy of the Chalk (Ulster White Limestone Formation) in Northern Ireland. Report of the Institute of Geological Sciences, No. 77/24. 
Fletcher, T P. 1967. Correlation of the Cretaceous exposures of east Antrim. Unpublished MSc Thesis, Queens University, Belfast. 
Hopson, P M. 2005. A stratigraphical framework for the Upper Cretaceous Chalk of England and Scotland, with statements on the Chalk of Northern Ireland and the UK Offshore Sector. British Geological Survey Research Report RR/05/01 102pp. ISBN 0 852725175 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
N28 N35