Category:Chalk Group Lithostratigraphy: Marlborough Downs/Berkshire Downs/Chilterns

The Chalk Group of this region has some distinct lithostratigraphical features compared to adjacent areas. In the Lower Chalk, an erosive calcarenite (Totternhoe Stone) has removed part of the succession, and in the Middle and Upper Chalk there is a variably developed series of hardgrounds (the Chalk Rock & Top Rock), that condense out parts of the thicker successions seen in the Southern Region. The lithostratigraphical scheme of Bristow et al. (1997) remains largely untested over the region (Wood, 1996), parts of which have recently been mapped by the BGS (e.g. Shephard-Thorn et al., 1994) following the traditional tripartite subdivision of the Chalk outlined by Jukes-Browne & Hill (1903, 1904). The following summarises the lithostratigraphical nomenclature applicable to the region: