Category:Southern Region Chalk Group Lithostratigraphy: Revised Stratigraphy of Rawson et al. (2000)
At a meeting of the Geological Society Stratigraphy Commission at the BGS in November 1999, a mappable lithostratigraphical subdivision of the Chalk Group was agreed for southern England. This scheme is essentially that detailed by Bristow et al. (1997), with the following modifications:
- The Chalk Group is subdivided into two major subdivisions: the Grey Chalk Subgroup (= the interval from the base of the Chalk Group to the sub-Plenus Marls erosion surface), and the White Chalk Subgroup (= the interval from the sub-Plenus Marls erosion surface to the top of the Chalk Group).
- The various Chalk Group Members described by Bristow et al. (1997) are elevated to formational status.
- The base of the Zig Zag Chalk Formation is coincident with the base of the Cast Bed rather than the Tenuis Limestone.
- The base of the Holywell Nodular Chalk Formation is coincident with the sub-Plenus Marls erosion surface (i.e. lower than the base of the Holywell Nodular Chalk Member of Bristow et al., 1997).
- The Plenus Marls are designated Member status.
- The Tarrant and Spetisbury Chalk Members of Bristow et al. (1997) remain as such, and comprise subdivisions of the Culver Chalk Formation.
BRISTOW, C. R., MORTIMORE, R. N. & WOOD, C. J. 1997. Lithostratigraphy for mapping the Chalk of southern England. Proceedings of the Geologists' Association, Vol. 108, 293-315.
RAWSON, P F, ALLEN, P, GALE, A. 2001. The Chalk Group - a revised lithostratigraphy. Geoscientist, 11, 21.
This category currently contains no pages or media.