| Computer Code: |
BHCK |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Campanian Age (KC)
— Campanian Age (KC) |
| Lithological Description: |
Limestone (chalk), with common bands of very large flints and tabular flints. Some green-coated chalk pebble beds near the base and as a prominent bed associated with sponges in the middle of the sequence. Hard pellet chalk in softer matrix is common at some levels Divided into three main "Beds" (A, B and C) each further divided into numbered "units". Each "Bed" separated by marked bedding planes that are locally emphasized by weathering. There are a number of notable fossil acmes throughout the formation. Considered to be much finer-grained than older gritty members and termed "White Chalk" by Wolfe (1968). A distinctive massive flint band, which marks the upper limit of Gonioteuthis, is termed the Whitehead Flint Band (of Bed status) whose type reference section is the old quarry at Whitehead [J 474 913]. |
| Definition of Lower Boundary: |
The base is defined by reference to the uppermost pebble bed of the underlying Creggan Chalk Formation (q.v.) and the stromatolitic "mulatto" surface in marginal areas. |
| Definition of Upper Boundary: |
The upper boundary is taken at the well-developed erosional surface at the base of the Larry Bane Chalk Formation. See Fletcher (1977). |
| Thickness: |
Combined thickness at the type-site of 24.19m. Bed A 8.33m, Bed B 8.69m and Bed C 7.17m. |
| Geographical Limits: |
In Northern Ireland. The formation is best developed in the North Antrim and East Antrim (Midland Valley) basins. It is overlapped by younger chalk members towards the structural highs of the Highland Border and Londonderry Shelf areas. |
| Parent Unit: |
Ulster White Limestone Group (UWLF)
|
| Previous Name(s): |
Boheeshane Chalk Member [Obsolete Name and Code: Use BHCK]
(-4461)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Larry Bane Bay - Boheeshane Bay in the North Antrim Basin. See Fletcher (1967, p.85, Figure 19). |
| Reference Section |
The Whitehead Flint Band is displayed at the reference section at the old quarry (a landfill site) at Whitehead [J474 913]. |
| Reference(s): |
| Wolfe, M J. 1968. Lithification of a carbonate mud: Senonian Chalk in Northern Ireland. Sedimentary Geology, Vol.2, 263-290. |
| 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 Unpublished MSc Thesis, Queens University, Belfast.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 |
