Southern Region Chalk Group Lithostratigraphy: Sussex lithostratigraphy of Mortimore (1986a) - Kingston Beds

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The Kingston Beds, c. 13 m thick in the Lewes district (Lake et al., 1987), are marked by the lowest of the three Bridgewick Marls at the base, and by the base of the Lewes Marl at the top (Mortimore, 1986a). They comprise hard, nodular, flinty chalks with incipiently developed hardgrounds (Lake et al., 1987). The Bridgewick Marls, up to 0.12 m thick, have variably developed plastic and brittle textures, and are associated with large courses of nodular flints, named the Bopeep Flints (Mortimore, 1986a). The Bopeep Flints and Bridgewick Marls form part of the 'Basal Complex' at Dover, which traditionally has been used to infer the equivalent horizon of the Chalk Rock, and thus mark the boundary of the traditional Middle Chalk and Upper Chalk (Mortimore & Wood, 1986). These flints are overlain by other conspicuous flint markers, including the Breaky Bottom Flint and the Lewes Tubular Flints (Mortimore, 1986a). The latter are highly distinctive, and form an interconnected network of hollow-centred cylindrical flints that are laterally persistent over a huge geographical area, and of enormous value for correlation. The interval from the Breaky Bottom Flint to the base of the Lewes Marl was named the upper Kingston Nodular Chalks by Mortimore (1986a).

The Kingston Beds have a rich and diverse fauna. The terminal acme of the brachiopod Terebratulina lata occurs at the base of the Kingston Beds, but other brachiopods, particularly Cretirhynchia and Orbirhynchia occur widely through this horizon (Lake et al., 1987). Amongst the inoceramid bivalves, species of Mytiloides are characteristic, and echinoids are represented by Gauthieria radiata, Sternotaxis plana and Micraster leskei (Lake et al., 1987). The fauna of the upper Kingston Nodular Chalks contains an aragonitic mollusc fauna, comprising particularly ammonites, that equates with the Reussianum Fauna of the Chalk Rock.

Macrofossil Biozonation: lower S. plana Zone

Correlation: see Correlation with other Southern Region Chalk Group classifications

see Correlation with other UK Chalk Group successions

References[edit]

LAKE, R D, YOUNG, B, WOOD, C J & MORTIMORE, R N. 1987. Geology of the country around Lewes. Memoir of the British Geological Survey.

MORTIMORE, R N.1986a. Stratigraphy of the Upper Cretaceous White Chalk of Sussex. Proceedings of the Geologists' Association, Vol. 97(2), 97-139.

MORTIMORE, R N & WOOD, C J.1986. The distribution of flint in the English Chalk, with particular reference to the 'Brandon Flint Series' and the high Turonian flint maximum. In SIEVEKING, G de C & HART, M B. The scientific study of flint and chert. Cambridge University Press, Cambridge.

See: marl, flint, nodular chalk, Basal Complex, Upper Chalk (Traditional classification), Lewes Tubular Flints, Reussianum Fauna, Chalk Rock (Type area)