Chalk Group Lithostratigraphy: East Anglia - Twin Marls

These marls were identified and named by Ward et al. (1968) in the Middle Chalk of the Thetford district where they occur as two closely associated seams 100mm thick and 40 mm thick, and they have also been correlated in borehole resistivity logs across East Anglia (Murray, 1986). They equate with Deepdale Marl 1 of the northern England Chalk Group succession (Mortimore & Wood, 1986; Gaunt et al., 1992), and in the Trunch Borehole [TG 2933 3455] in north Norfolk are represented by a 20 mm marl with its base at a depth of 471.74 m (Arthurton et al., 1994).

Macrofossil Biozonation: upper T. lata Zone

References

ARTHURTON, R S, BOOTH, S J, MORIGI, A N, ABBOTT, M A W & WOOD, C J. 1994. Geology of the country around Great Yarmouth. Memoir of the British Geological Survey.

GAUNT, G D, FLETCHER, T P & WOOD, C J. 1992. Geology of the country around Kingston-upon-Hull and Brigg. Memoir of the British Geological Survey.

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.

WARD, W H, BURLAND, J B & GALLOIS, R W. 1968. Geotechnical assessment of a site at Mundford, Norfolk, for a large Proton Accelerator. Géotechnique, Vol. 18, 399-431.