Ammonites from the basal Ampthill Clay (Upper Jurassic) at Abingdon and Cumnor, Oxfordshire

Temporary sections of Upper Oxfordian strata exposed at Abingdon, Oxfordshire in 1972, 1989 and 1994 are described. Exposures of the Ampthill Clay Formation were revealed, with, at the base, a previously unknown lithostratigraphic unit named here the Abingdon Marl Member. Further exposures of the basal Ampthill Clay exposed at Cumnor, Oxfordshire, in the 1960s and 1970s are described. Distinctive and prolific ammonite faunas belonging to the Boreal Glosense Zone (Sub-Boreal Pumilus and Cautisnigrae Zones) were collected from these exposures. The correlation of the exposures with Middle and Upper Oxfordian strata elsewhere in southern England suggests that a more zonally complete Ampthill Clay succession is normally present in the area than had previously been suspected. Representatives of the cardioceratid and perisphinctid faunas are figured.