BGS Zone 26(=UKB22 of Hart et al., 1989)
Base: Inception of Bolivinoides draco draco (not seen onshore, but present in the North Sea Basin).
Top: Inception of Abomphalus mayaroensis (not seen onshore, but present in the North Sea Basin).
- Abomphalus intermedia and Rosita patelliformis appear at or near the base of the foraminifera zone.
Macrofaunal correlation: Early B. occidentalis Zone s.l. and ?B. junior Zone.