Jukes-Browne & Hill (1903, 1904) - Micraster cortestudinarium Zone

Biostratigraphical correlation: It is inferred that Jukes-Browne & Hill (1904) largely followed Rowe (1900) in the definition of this zone. It therefore equates with the upper S. plana Zone, and a variable interval from within the top of the M. cortestudinarium Zone to the basal M. coranguinum Zone, of current usage.

Lithostratigraphical correlation: Equates with the upper Lewes Nodular Chalk Formation and, depending on how the top of the zone is defined, also the basal part of the Seaford Chalk Formation of southern England.

Age: Late Turonian & Early Coniacian.