Chalk Group Lithostratigraphy: East Anglia - Beacon Hill Grey Chalk Member

The Beacon Hill Grey Chalk Member (c. 5 m thick), representing the youngest onshore chalk in the UK , occurs in a chalk mass enclosed in glacial drift at Trimingham. It equates with the Grey Beds of Brydone (1906, 1908) and Peake & Hancock (1970), and comprises grey chalk with five flint bands and a c. 0.1 m thick calcarenite towards the top, the latter containing huge, thick-shelled specimens of the oyster Pycnodonte vesiculare and large examples of the echinoid Galerites (Peake & Hancock, 1970). A highly characteristic morphotype of the echinoid Echinocorys occurs in the chalk above the calcarenite, and corresponds with forms from an exposure in the Netherlands where it co-occurs with Belemnella sumensis of the upper Lower Maastrichtian B. sumensis Zone in Germany (Johansen & Surlyk, 1990). The lower boundary of the member is the base of the first soft, grey chalk, labelled 'A' by Peake & Hancock (1970, Fig. 7); there is no upper boundary.

Macrofossil Biozonation: B. occidentalis Zone

Correlation: see Correlation with other UK Chalk Group successions

References

BRYDONE, R M.1906. Further notes on the stratigraphy and fauna of the Trimingham Chalk. Geological Magazine, Vol. 43, 13-22, 72-78, 124-31, 289-300.

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.