Chalk Biozone 3 - Wrevittia cassidata

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Age: Late Cenomanian. Macrofaunal correlation: The C. guerangeri Zone to the N. juddii Zone.

Definition: The interval between the LAD of Epelidosphaeridia spinosa and the LAD of Wrevittia cassidata.

Comments: The top of the Biozone is also marked by the LADs of Adnatosphaeridium tutulosum, Apteodinium granulatum and Carpodinium obliquicostatum (see Foucher, 1981; Costa & Davey, 1992; Foucher & Monteil, 1998). The LAD of Microdinium? reticulatum and the FAD of Adnatosphaeridium tutulosum mark the C. guerangeri Zone-M. geslinianum Zone boundary (Foucher, 1979; 1981; Foucher & Monteil, 1998).

Lithostratigraphical correlation: The upper Zig Zag Chalk and the lower Holywell Nodular Chalk formations (Southern Province), the Ferriby Chalk and the Welton Chalk formations (Northern Province) and the upper Hidra and lowermost Herring formations (North Sea).