Chalk Group Lithostratigraphy: East Anglia - Upper Inoceramus Bed

The Upper Inoceramus Bed equates with the 2nd Inoceramus Bed of Jeans' (1973) description of the Chalk of northern England. It occurs widely across East Anglia, from Sudbury (Pattison et al., 1993) in the south to Hunstanton (Gallois, 1994) in the north. It comprises coarse, bioclastic chalk, with abundant fragments of the bivalve Inoceramus, usually overlying a sharply defined basal erosion surface, locally with glauconitised and phosphatised chalkstone pebbles (Gallois, 1994). In north Norfolk, the bed is c. 1 m thick (Gallois, 1994), but in the south of the district, around Sudbury, it is about half this (Pattison et al., 1993). In boreholes in the Bury St. Edmunds district a single unit of shell detrital chalk appears to be equated with the two Inoceramus Beds of northern England (Bristow, 1990). Shell fragments of the bivalve Inoceramus is the dominant fossil, with few other faunal records (Gallois, 1994).

Macrofossil Biozonation: M. mantelli Zone, ? M. saxbii Subzone

Correlation: see Correlation with other UK Chalk Group successions

References

BRISTOW C R. 1990. Geology of the country around Bury St. Edmunds. Memoir of the British Geological Survey.

GALLOIS, R W.1994. Geology of the country around King's Lynn and The Wash. Memoir of the British Geological Survey.

JEANS, C V. 1973. The Market Weighton structure: tectonics, sedimentation and diagenesis during the Cretaceous. Proceedings of the Yorkshire Geological Society, Vol. 39, 409-44

PATTISON, J., BERRIDGE, N. G., ALLSOP, J. M. & WILKINSON, I. P. 1993. Geology of the country around Sudbury (Suffolk). Memoir of the British Geological Survey, Sheet 206 (England & Wales).