Jukes-Browne & Hill (1903, 1904) - Actinocamax quadratus 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 an interval from near the base of the O. pilula Zone to at or just below the top of the G. quadrata Zone. It is unclear if Jukes-Browne & Hill (1904) used the top of the range of Gonioteuthis to fix the top of the zone (as used to define the top of the current G. quadrata Zone), or the lowest occurrence of Belemnitella, as apparently used by Rowe (1900).
Lithostratigraphical correlation: Equates with the middle and upper parts of the Newhaven Chalk Formation, the Culver Chalk Formation, and probably also the basal part of the Portsdown Chalk Formation of southern England.