Chalk Group Lithostratigraphy: East Anglia - Trimingham Sponge Beds Member

The Trimmingham Sponge Beds Member (c. 2.9 m thick) equates with the Sponge Beds of Brydone (1908), and is named after Trimingham, on the north Norfolk coast, where this chalk occurs as a series of masses enclosed in glacial drift (Johansen & Surlyk, 1990). The member comprises indurated, yellow-stained, spongiferous chalk, with local concentrations of pyrite, erosion surfaces with glauconitised pebbles and four flint bands with thick white cortices in the upper part (Johansen & Surlyk, 1990). The basal boundary is the top of the sponge bed labelled 'O' in Peake & Hancock (1970, Fig. 7), and the top is the top of a thick 'greasy' marl labelled 'G' in Peake & Hancock (1970, fig. 7).

Macrofossil Biozonation: B. lanceolata .Zone s.l. & B. occidentalis Zone

Correlation: see Correlation with other UK Chalk Group successions

References

BRYDONE, R M.1908. On the subdivisions of the Chalk at Trimingham (Norfolk). Quarterly Journal of the Geological Society of London, Vol. 64, 401-12.

JOHANSEN, M B & SURLYK, F.1990. Brachiopods and the stratigraphy of the Upper Campanian and Lower Maastrichtian Chalk of Norfolk, England. Palaeontology, Vol. 33(4), 823-872.

PEAKE, N B & HANCOCK, J M. 1970. The Upper Cretaceous of Norfolk [reprinted with corrigenda and addenda] In LARWOOD, G P & FUNNELL, B M (eds.), The Geology of Norfolk. London & Ashford.

See: spongiferous chalk, hardground