The stratigraphy of the Kimmeridge Clay Formation (Jurassic) at Westbury, Wiltshire, U.K.

The former Blue Circle Cement quarry at Westbury, Wiltshire exposed extensive sections in the lower part of the Kimmeridge Clay Formation, and a continuously cored borehole proved the lowest part of the formation and the underlying succession down to the top of the Oxford Clay Formation. The succession exposed in the quarry between 1979 and 2001 ranged from the Cymodoce to Eudoxus zones, and that in the borehole from the Baylei to Mutabilis zones. Taken together, the quarry and borehole proved the most complete section through the Kimmeridge Clay in a region where much of the formation has never been exposed. The lithological and palaeontological successions proved at Westbury are closely similar to those proved in continuously cored boreholes throughout the English outcrop and subcrop of the formation and can be matched in detail with that exposed in the type area on the Dorset coast. When the quarry was in work the sections yielded a profuse ammonite fauna that enabled the Cymodoce–Mutabilis and Mutabilis–Eudoxus zonal boundaries to be studied in detail. They also yielded a diverse bivalve and vertebrate fauna.