The lithostratigraphy of the upper Oxfordian and lower Kimmeridgian Beds of South Dorset, England

Abstract

Studies of detailed sections have validated Blake's (1875) concept of Passage Beds between the Corallian Beds (Upper Oxfordian) and Kimmeridge Clay (Kimmeridgian-Tithonian) in South Dorset. Blake's (1875) term ‘Passage Beds’ is applied to a coherent group of dominantly arenaceous sediments straddling the Corallian Beds-Kimmeridge Clay boundary and these beds are included in the Upper Calcareous Grit, whose upper boundary is revised to include the arenaceous facies of the lower part of the Kimmeridge Clay (in Dorset). The lower junction of the Kimmeridge Clay is raised to include only the clays of the Aulacostephanus mutablis to Zaraiskites albani Zones in the lithostratigraphic unit—Kimmeridge Clay. The faunas of the Passage Beds are akin to those of the Corallian Beds and bear only slight resemblance to those of the Kimmeridge Clay.