Lithological and faunal stratigraphy of the Aptian and Albian (Lower Cretaceous) of the type Speeton Clay, Speeton, north-east England

Study of the Aptian and Albian parts of the Speeton Clay Formation at Speet on, North Yorkshire, has produced a detailed stratigraphy and a large colle ction of stratigraphically constrained fossils, despite the general poor st ate of exposure. This has allowed the development of a readily applicable b ed numbering scheme and detailed faunal (macrofossil, foraminifera and ostr acod) range charts. The Barremian-Aptian boundary is marked by the appearan ce of abundant examples of the ammonite Prodeshayesites and a marked lithol ogical change from black shale to sandy mudstone. Higher parts of the Aptia n have yielded abundant faunas, including ammonites of the fissicostatus, f orbesi and deshayesi zones; the base of the forbesi Zone marked by the inco ming of Ewaldi Marl facies. Poorly fossiliferous silty shales of the Albian tardefurcata Zone are succeeded by a bed with glauconite and phosphate peb bles, interpreted as marking the base of the mammillatum Superzone. This is overlain by fossiliferous clays of the Lower Albian and part of the Middle Albian. Range charts for macrofossils and microfossils from the Upper Barr emian to Middle Albian of Speeton are constructed and biozones indicated. A ptian and Lower Albian successions inland of Speeton are highly variable, p robably due to intra mid-Cretaceous fault movements. The same general strat igraphy as at Speeton, however, may be seen across much of the southern Nor th Sea.