Gaster (1924, 1927, 1929, 1932, 1937, 1941, 1944) - Schloenbachia varians Zone
Biostratigraphical correlation: Inferred to equate with the M. mantelli Zone, M. dixoni Zone and C. inerme Zone of current usage.
Lithostratigraphical correlation: Inferred to equate with the West Melbury Marly Chalk Formation of southern England.
Subzones: Stauronema carteri Subzone
Age: Early to Mid Cenomanian