| Computer Code: |
BLCH |
Preferred Map Code: |
BdCk |
| Status Code: |
Full |
| Age range: |
Coniacian Age (KO)
— Campanian Age (KC) |
| Lithological Description: |
[Obsolete: use SECK, NCK]
Firm, smooth, white flinty chalk; some thin marl seams present. |
| Definition of Lower Boundary: |
The lower boundary is conformable change from hard nodular chalk of the Lewes Nodular Chalk Formation up into firm smooth chalk of this member. |
| Definition of Upper Boundary: |
The upper boundary is conformable at the incoming of soft to firm smooth white chalk with conspicuous large flint seams and including the fauna indicative of the quadrata zone of the Tarrant Chalk Member. |
| Thickness: |
75 - 90 metres in the Shaftesbury area. |
| Geographical Limits: |
Confined to the Shaftsbury Geological Sheet 313 area. Previously considered to be continuous across the whole of southern England. It is equivalent to the combined Seaford and Newhaven Chalk formations that are mappable separately elsewhere. |
| Parent Unit: |
none recorded or not applicable
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
General area around Blandford Forum, Dorset. |
| Reference Section |
Old railway cuttings on the military sidings, Blandford, (see Bristow, et al. 1995, p.131). Five cuttings show good exposures in the upper part of the member. |
| Reference(s): |
| Bristow, C R, Barton, C M, Freshney, E C, Wood, C J, Evans, D J, Cox, B M, Ivimey-Cook, H C, and Taylor, R T. 1995. Geology of the country around Shaftesbury. Memoir of the British Geological Survey, Sheet 313 (England and Wales). |
| 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 |
| Barton, C M. 1991. Geology of the Blandford Forum district (Dorset). British Geological Survey Technical Report WA/91/81. |
| Gaster, C T. 1944. The stratigraphy of the Chalk of Sussex, Part III. Western area. Arun Gap to the Hampshire boundary, with zonal map. Proceedings of the Geologists' Association, Vol.55, 173-188, |
| Bristow, C R. 1990. Geology of Sheet ST92SW (Berwick St John, Wiltshire). British Geological Survey Technical Report WA/90/49. |
| Mortimore, R N. 1986. Stratigraphy of the Upper Cretaceous White Chalk of Sussex. Proceedings of the Geologists' Association, Vol.97(2), 97-139. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E313
|
