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

From Earthwise
Jump to navigation Jump to search

The Caburn Beds, c. 5 m thick in the Lewes district (Lake et al., 1987), are marked by the Southerham Marl 1 at the base, and extend up to the base of the Caburn Marl (Mortimore, 1986a). They comprise hard, nodular locally flinty, spongiferous chalk (Mortimore, 1986a). Southerham Marl 1 is typically thick (up to 0.2 m) and plastic textured, and locally characterised by an abundance of the large agglutinating foraminifera Labyrinthidoma (= Coskinophragma of Mortimore, 1986a). Conspicuous sponge beds and flints (the Caburn Sponge Beds and Caburn Flints) occur in the higher part of the Caburn Beds (Mortimore, 1986a).

The fauna of the Caburn Beds includes inoceramid bivalves, the ammonites Romaniceras deverianum, Subprionocyclus and Lewesiceras, and the echinoids Epiaster michelini and Gauthieria radiata (Mortimore, 1986a; Lake et al., 1987). The Caburn Sponge Beds preserve a limited aragonitic mollusc fauna, analagous to but not correlative with the Reussianum Fauna of the Chalk Rock, including the gastropod Bathrotomaria, and the ammonites Yezoites [Otoscaphites] and Sciponoceras (Lake et al., 1987).

Macrofossil Biozonation: upper T. lata 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.

See: marl, flint, nodular chalk, spongiferous chalk, Southerham Marl 1, Reussianum Fauna, Chalk Rock (type area).