Griffith & Brydone (1911); Brydone (1912) - Micraster coranguinum Zone
Biostratigraphical correlation: Equates with an interval from within the lower part of the M. coranguinum Zone to the top of the U. socialis Zone of current usage. Griffith & Brydone (1911) restricted the concept of the M. coranguinum Zone to exclude strata below the range of the zonal index. Brydone (1912) advocated the future establishment of a separate Zone of Uintacrinus, and stated (p 17) that 'future references in this paper to the cor-anguinum Zone should be taken as not intended to apply to the Uintacrinus band unless the latter is expressly mentioned'.
Lithostratigraphical correlation: Equates with the middle and upper Seaford Chalk Formation and basal Newhaven Chalk Formation of southern England.
Age: Late Coniacian and Early Santonian.