SEDIMENTATION AND LITHOSTRATIGRAPHY OF THE NORTH-SEA-DRIFT AND LOWESTOFT-TILL FORMATIONS IN THE COASTAL CLIFFS OF NORTHEAST NORFOLK, ENGLAND

The most complete terrestrial sequence of Anglian (Elsterian) glacial sediments in western Europe was investigated in northeast Norfolk, Eng land in order to reconstruct the evolution of the contemporary palaeoe nvironments. Lithostratigraphically the glacial sediments in the north east Norfolk coastal cliffs can be divided into the North Sea Drift an d Lowestoft Till Formations. Three of the diamicton members of the Nor th Sea Drift Formation (Happisburgh, Walcott and Cromer Diamictons) we re deposited as lodgement and/or subglacial deformation till by ground ed ice, but one, the Mundesley Diamicton, is waterlain and was deposit ed in an extensive glacial lake. Sands and fine sediments interbedded between the diamictons represent deltaic sands and glaciolacustrine se diments derived not solely from the melting ice in the north but also from extra-marginal rivers in the south. The Lowestoft Till Formation is not well perserved in the cliffs but includes lodgement till (Marly Drift till) and, most probably, associated meltwater deposits. Extens ive glaciotectonism in the northern part of the area is shown to relat e to oscillating ice that deposited the Cromer Diamicton and also part ially to the ice sheet that deposited the Marly Drift till. It is sugg ested that during the Anglian Stage the present day northeast Norfolk coast was situated on the northwestern margin of an extensive glaciola custrine basin. This basin was dammed by the Scandinavian ice sheet in the north and northeast. Because the grounding line of this ice sheet oscillated in space and time, part of the North Sea Drift diamictons were deposited directly by this ice. However, during ice retreat phase s glaciolacustrine deposition comprised waterlain diamicton, sands and fines. When the Scandinavian ice sheet was situated in northernmost N orfolk, the British ice sheet (responsible for depositing the Marly Dr ift facies) entered the area from the west. This ice sheet partially d eformed the North Sea Drift Formation sediments in the northern part o f the area but not in the south, where the British ice sheet apparentl y terminated in water. The interplay of these two ice sheets on the no rthern and western margins of the glacial lake is thought to be the ma jor determining factor for the accumulation of thick glacial deposits in this area during the Anglian glaciation.