The Middle Jurassic succession at Ketton, Rutland

Abstract

The cement quarry at Ketton is the most important Middle Jurassic locality in inland England. For many years it has exposed the Lincolnshire Limestone, Rutland and Blisworth Limestone Formations. Excavations in the lower quarry have allowed access to the Northampton Sand and Grantham Formations, and temporarily to the Whitby Mudstone Formation, while extensions of the upper quarry, and the effects of recently exposed faults, additionally reveal complete sections in the Blisworth Clay, Cornbrash and Kellaways Formations. The site therefore allows the description of the whole succession of the Aalenian to Lower Callovian strata developed in the East Midlands: the Inferior Oolite Group, the Great Oolite Group and the lowest part of the Ancholme Group. In this paper the succession is summarized, incorporating data from stratigraphic revisions by Bradshaw (1978) and Ashton (1980). Measured sections and logs for each formation are presented, in order to provide a basis for more interpretative investigations and for regional correlation. New members are defined: the Castle Member within the Rutland Formation, and the Grange, Tinwell Lodge and Ketton Heath Members within the Blisworth Clay Formation, in each case with Ketton as the type section. Appendices relate previous bed-numbering schemes to our stratigraphy, and assign the ostracod faunas recorded by Bate (1967) from the Rutland Formation to their precise horizons.