The Late Devensian terminal moraine ridge at Garret Hill, Stiffkey valley, north Norfolk, England

Abstract

SUMMARY Glacial stratigraphy and ice-marginal processes within the limit of the Late Devensian Glaciation in eastern England were investigated at Garret Hill, situated on the eastern flank of the Stiffkey valley, north Norfolk. Glacial sediments are divided into four lithofacies units. LFA-1 and 2 consist of chalk-rich diamicton and flint-rich outwash deposits, respectively. These extend beyond the Late Devensian ice-limit and are attributed to glaciation during the Middle Pleistocene. LFA-3 and 4 comprise a red diamicton and meltwater deposits that are equated to the Holkham Till and Ringstead Sand and Gravel respectively, deposited during the Late Devensian Glaciation. It is proposed that a terminal moraine ridge was formed during the Late Devensian Glaciation as a Scottish-sourced ice sheet flowed southwards along the western margin of the North Sea Basin. The moraine is identified by the distribution of ridges and hummocks that border the outcrop of Holkham Till. At Garret Hill, these landforms contain folded chalk-rich diamicton (LFA-1) and flint-rich outwash sediments (LFA-2) overlain by Holkham Till. This event is likely to have been accompanied by the formation of glacial lakes in the Stiffkey valley, impounded between the blocking ice sheet to the north and the Cromer Ridge to the south. The site is only the second site where the Holkham Till has been found overlying glacial deposits of Middle Pleistocene age.