The BGS Lexicon of Named Rock Units — Result Details

Ballintoy Chalk Formation

Computer Code: BTC Preferred Map Code: notEntered
Status Code: Full
Age range: Campanian Age (KC) — Campanian Age (KC)
Lithological Description: Limestone (chalk) with small flints scattered in the lower part and small discontinuous tabular flints in the upper part. The formation can be divided into two "Beds" (A and B) across a conspicuous separation plane. The formation is terminated by the "wavy-bedded" Altachuile Breccia (of ?member status).
Definition of Lower Boundary: The lower boundary conformably overlies "Bed" B of the Larry Bane Chalk Formation. Oldest of the post-Larry Bane Chalk "Subgroup".
Definition of Upper Boundary: The upper boundary is conformably succeeded by the Glenarm Chalk Formation above the Altachuile Breccia (?Member).
Thickness: 12.65m at its type site with Bed A 9.65m and Bed B 3.00m.
Geographical Limits: Northern Ireland. The principal outcrop is within the North Antrim and East Antrim (Midland Valley) basins. Oversteps the Larry Bane Formation onto the Southern Uplands, Highland Border and the northernmost part of the Londonderry Shelf. North Antrim and Midland (East Antrim) basins and on the eastern Londonderry Shelf. The member is continuous around the outcrop from Portrush to north Belfast.
Parent Unit: Ulster White Limestone Group (UWLF)
Previous Name(s): Ballintoy Chalk Member (-3248)
White Bay Chalk (-1402)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  The type section is taken on gently dipping rock platforms in Ballintoy Harbour [D 040 456] in the North Antrim Basin. More accurate measurements are achieved from Larry Bane Head and Quarry to the east. 
Type Area  North Antrim and Midland (East Antrim) basins and on the eastern Londonderry Shelf. The member is continuous around the outcrop from Portrush to north Belfast. 
Reference Section  The type section defined by Fletcher in his 1967 thesis is at White Bay where the maximum development of the formation was formerly visible in air-weathered cliffs. 
Reference(s):
Fletcher, T P. 1967. Correlation of the Cretaceous exposures of east Antrim. Unpublished MSc Thesis, Queens University, Belfast. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable