Northern Ireland Chalk nomenclature (Ulster Cretaceous Province) - Ulster White Limestone Group: Post-Larry Bane Chalk Subgroup: Ballycastle Chalk Formation
The Ballycastle Chalk Member was first proposed in Fletcher (1977) and adopted in BGS publications subsequently. It is regarded as a formation herein.
West of Ballycastle Pier [D 120 415].
Primary Reference Section
Ballymagarry Quarry, Castle Point Quarry and cliffs and foreshore eastward to Ballycastle.
None but informally divided into units A to G from the base.
Limestone (chalk) with nodular flint bands which have a carious habit in the upper part of the formation. Divided into seven ‘Beds’ (A to G).
Definition of upper boundary
Erosional contact with Palaeogene Basalts or Quaternary deposit.
Definition of lower boundary
Conformable on the Port Calliagh Chalk Formation at a prominent weathered-out bedding plane at the top of ‘Bed’ F of that lower formation and characterised by tabulate flints.
13.72m at type-site.
Limited to the Ballymagarry and Ballycastle areas by pre-Palaeogene erosion
Forms the upper part of the Ballycastle White Limestone of Wood (1967).
Ballycastle Chalk Member.
Ulster White Limestone Group.
Age and biostratigraphy
Upper Cretaceous, Maastrichtian. Belemnella occidentalis Zone.
Fletcher (1967, 1977).