The lithostratigraphical context of the English Chalk Rock (Turonian)

Correlations of borehole geophysical logs in the middle and upper Turonian Chalk Group are used to consider recent proposals for a revision understanding unit hardgrounds (Chalk Rock) associated stratigraphy developed across parts southern England. Along northern edge London Wessex basins, reveal laterally continuous framework correlatable inflection patterns New Pit Chalk, with package sediment immediately below Rock showing trend lateral thinning increasingly condensed sedimentation westwards into areas where oldest Hardgrounds (Ogbourne Hardground) is present. However, apart from local absence Glynde Marls Complex near top there no evidence presence major erosion event. This questions interpretations microcrinoid data, reportedly that Ogbourne Hardground lithifies stratigraphical level lower part this corresponding hiatus related short-lived globally significant sea fall. Macrofossil biostratigraphy supports log interpretations, both younger older Hardground. The data consistent Wiltshire Berkshire representing highly equivalent thickened nodular chalk fabrics at base Lewes Nodular eastern Chilterns.