A sponge-rich, nodular horizon, just below the Seven Sisters Flint in Sussex, marks the basal sequence boundary, but no lowstand systems tract is preserved above this in Sussex (Grant et al., 1999). On the Isle of Wight, the sequence boundary is a yellow iron-stained hardground with inoceramid shell debris, and a further hardground a short distance above marks the top of a thin lowstand systems tract and the beginning of a transgressive systems tract (Grant et al., 1999). The maximum flooding surface is marked by the Seven Sisters Flint in Sussex and the East Cliff Semitabular/Oldstairs Bay Flint in Kent, above which the highstand systems tract comprises regularly flinty chalk (Grant et al., 1999).
GRANT, S F, COE, A L, ARMSTRONG, H A. 1999. Sequence stratigraphy of the Coniacian succession of the Anglo-Paris Basin. Geological Magazine, 136, 17–38.