| Computer Code: |
TACH |
Preferred Map Code: |
TCk |
| Status Code: |
Full |
| Age range: |
Campanian Age (KC)
— Campanian Age (KC) |
| Lithological Description: |
Soft white chalk with relatively widely spaced but large flint seams. |
| Definition of Lower Boundary: |
The lower boundary is conformable. As defined (Mortimore, 1986), the base of the Culver Chalk lies low in the quadrata Zone, at the Castle Hill Marl. Well-developed marls commonly occur for several metres above the Castle Hill Marls, up to and including the Pepper Box Marls, which are now taken as the base. Approximately coincident with the Arundel Sponge Beds. |
| Definition of Upper Boundary: |
The upper bounday is conformable (but see note on thickness). Inferred to be at the Whitecliff Flint at the boundary between the Sompting and Whitecliff beds of Mortimore (1986). |
| Thickness: |
35 to 45 m in Sussex, about 30 m in Dorset, but can be considerably reduced where synsedimentary channelling occurs. |
| Geographical Limits: |
Limited to Sussex, Hampshire, Wiltshire and Dorset and as widely spaced outliers to the north in the Southern Province. Its occurrence and distribution beneath the Quaternary deposits of East Anglia in the Transitional Province is not well known. |
| Parent Unit: |
Culver Chalk Formation (CUCK)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Partial Type Section |
Quarry face in old pit at the foot of The Cliff, Tarrant Rushton, (see Barton, 1992, figure 4). 14 m section that starts about 6 m above the base of the formation. |
| Type Area |
Strata well developed along the Tarrant Valley, Dorset. |
| Reference Section |
Section within the Whitecliff Bay cliffs on the Isle of Wight. The whole of the succession is visible but access difficult except at exceptionally low tides. Access by boat. |
| Reference(s): |
| 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, Mortimore, R N, and Wood C J. 1997. Lithostratigraphy for mapping the Chalk of southern England. Proceedings of the Geologists' Association, Vol. 108(4), 293-315. |
| Bristow, C R. 1991. Geology of the Tollard Royal - Tarrant Hinton district. British Geological Survey Technical Report WA/91/20. |
| 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). |
| Rawson, P F, Allen, P M and Gale, A. 2001. A revised lithostratigraphy for the Chalk Group. Geoscientist, Vol.11, p.21. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E300
E313
E314
E327
E341
E342
E343
|
