The BGS Lexicon of Named Rock Units — Result Details

Ballymagarry Chalk Formation

Computer Code: BMC Preferred Map Code: notEntered
Status Code: Full
Age range: Campanian Age (KC) — Campanian Age (KC)
Lithological Description: Limestone (chalk) with extremely large flat-lying and near-continuous flint bands. Divided into three "Beds" (A to C) separated by well-marked bedding planes.
Definition of Lower Boundary: The base conformably overlies the Portrush Chalk Formation at the level of a well-marked bedding plane immediately below the inception of large flat-lying and near continuous flint nodules.
Definition of Upper Boundary: The upper boundary is marked by the base of the prominent continuous flint band termed the Long Gilbert Flint Band within the Tanderagee Chalk Formation.
Thickness: 10.95m at its type-site.
Geographical Limits: Northern Ireland. Found throughout the Londonderry Shelf, North Antrim Basin and Southern Uplands High. Absent from the Midland Valley (East Antrim) Basin and Highland Border High presumably due to the effects of pre-Palaeogene erosion.
Parent Unit: Ulster White Limestone Group (UWLF)
Alternative Name(s): none recorded or not applicable
Type Section  Ballymagarry Quarry. 
Reference Section  The western side of Port More. 
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 Unpublished MSc Thesis, Queens University, Belfast. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable