BGS Zone 18 (=uppermost UKB14 and lower UKB15 of Hart et al., 1989)

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Base: Inception of Gavelinella cristata.

Top: Inception of Bolivinoides culverensis.


  • Stensioeina granulata polonica extinction at Peake’s Sponge Bed.
  • Stensioeina exsculpta gracilis inception in the middle part of the foraminiferal zone, at the Echinocorys elevata Band and lateral equivalents at the base of the M. testudinarius macrofaunal zone.


18i. (un-named subzone). Inception of Gavelinella cristata and Gavelinella stelligera to the inception of Stensioeina granulata perfecta

18ii. Stensioeina granulata perfecta Subzone: marked by the inception of the index species in the ‘mid’ U. socialis macrofaunal zone.

18iii. Bolivinoides strigillatus Subzone: marked by the inception of the subzonal index in the upper U. socialis macrofaunal zone, a little below Hawks Brow Flint and lateral equivalents.

18iv. (un-named subzone). Inception of Rosita fornicata, Rugoglobigerina pilula, Archaeoglobigerina cretacea and Heterohelix striata at the base of the U. anglicus macrofaunal zone.

Macrofaunal correlation: topmost M. coranguinum Zone (immediately below Peake’s Sponge Bed and lateral equivalents), U. socialis Zone, M. testudinarius Zone & U. anglicus Zone.

Age: Late Santonian & Early Campanian