The Banham Beds: a petrologically distinct suite of glacigenic deposits from central East Anglia

A petrologically distinct suite of clays, silts, sands, gravels and diamictons has been recognised in the area north-west of Diss, Norfolk. These deposits rest on Chalk and are overlain by the Anglian Lowestoft Formation. We propose the term Banham Beds for these deposits and interpret them as glacigenic in origin. Their pebble content, grain-size distribution, heavy mineral assemblage and clay mineralogy are all used to distinguish them from the adjacent Anglian North Sea Drift and Lowestoft formations. The genesis and significance of the Banham Beds are discussed and it is concluded that the deposits were lain down in a mainly fluviatile and lacustrine system near the margin of the North Sea Drift ice-sheet. The Banham Beds are thought to be derived partly from locally extensive pre-Anglian Kesgrave Sands and Gravels and Ingham Sand and Gravel together with abundant silt- clay grade outwash material derived from the North Sea Drift ice-sheet. We provisionally designate the Banham Beds as a member of the North Sea Drift Formation.