Griffith & Brydone (1911); Brydone (1912) - Holaster subglobosus Zone
Biostratigraphical correlation: Inferred to equate with the A. rhotomagense Zone, A. jukesbrownei Zone and C. guerangeri Zone.
Lithostratigraphical correlation: Inferred to equate with the Zig Zag Chalk Formation of southern England.
Age: Mid to Late Cenomanian