Upper Cretaceous Chalk in the North and South Downs, England: a correlation

Abstract

A correlation of the Upper Cretaceous White Chalk Formation between the North and South Downs is presented. All key marker bands, the marl seams, flint bands and many of the nodular-chalk seams correlate in detail. Differences occur where the North Downs Chalk is attenuated and marker bands are thus occluded. In addition, the major changes in lithology identified in the more complete stratotype sections in Sussex are also present in Kent. The following major lithological boundaries and markers are common to both Downs: the base of the Ranscombe Chalk at the junction between the Plenus Marls and the Melbourn Rock. the Glynde Marls at the base of the Lewes Chalk. the Shoreham/Eastcliff Marls at the base of the Seaford Chalk. The Buckle Marls at the base of the Newhaven Chalk are, however, absent from the Thanet coast where a different chalk lithofacies without marl seams and with few flint seams is developed. This local lithofacies is probably caused by sedimentation across a structural high. The South Downs successions continue into the Campanian with the Newhaven, Culver and Portsdown Chalks which are not preserved in the North Downs. A rationalisation of the lithostratigraphic terminology for the Chalk of the Weald in particular, and the Anglo-Paris Basin in general is proposed.