SUMMARY The lowermost part of the Welton Chalk Formation in eastern England conforms to a succession of eight beds, lettered here A to H in ascending order. Beds A and B are equated with the Plenus Marls ( Metoicoceras geslinianum Zone) of southern England. The Black Band (beds C to E) has yielded palynological assemblages containing the dinoflagellate cysts Adnatosphaeridium tutulosum and Carpodinium obliquicostatum. Their presence, along with the absence of Litosphaeridium siphonophorum, indicates a late Cenomanian age ( Neocardioceras juddii Zone) for the Black Band. Bed H contains the planktonic foraminiferan Praeglobotruncana praehelvetica, an early morphotype of a Turonian marker fossil. The dark, organic-rich marls of beds C to G are probably contiguous with those of the lowermost part of the Herring Formation in the North Sea Basin and together comprise the regional sedimentary record of a much more widespread ‘black shale’ depositional episode. Alternative hypotheses concerning the origin and timing of this episode are reviewed with reference to new microfossil evidence from eastern England. The late Cenomanian to early Turonian dinoflagellate cyst stratigraphy discussed here appears to be compatible with stratigraphies based on planktonic foraminifera, ammonites and geochemistry (δ 13 C) in north-west Europe and the western interior of the USA, possibly indicating connected basin water masses over much of the area during the Cenomanian–Turonian transition.