The Age and Origin of the Blakeney Esker of North Norfolk: Implications for the Glaciology of the Southern North Sea Basin

Abstract

The age and origin of the Blakeney ridge of eastern England have been debated for over a century. The feature is shown to be an esker formed in the late stages locally of a glaciation of Middle Quaternary age. The weight of evidence indicates that the esker was associated with the ice that laid down the Marly Drift of central north Norfolk, although this cannot be demonstrated conclusively. The flows that formed the Blakeney esker were subglacial. They took place from northwest to southeast along the length of the ridge, with at least the final phase occurring under hydrostatic pressure. It is likely that the esker developed during a glacial stillstand and under steep hydraulic gradients close to the ice sheet terminus. Although the esker conduit appears to have functioned largely as a Röthlisberger channel, there is evidence of simultaneous incision of the glacial bed. A valley is cut into bedrock beneath the esker. The esker and the buried valley may form the distal components of one of the broadly north-south aligned subglacial valleys that were trenched across the southern North Sea Basin in Middle Quaternary times. The complex assemblage of proglacial glaciofluvial landforms found to the south of the esker may represent the products of transport along the subglacial valley. The ice lobe that occupied the southern North Sea Basin may have left similar buried valley-proglacial fan complexes elsewhere along the northern fringe of East Anglia.

A polyphase glacitectonic model for ice-marginal retreat and terminal moraine development: the Middle Pleistocene British Ice Sheet, northern Norfolk, UK

“…ploughing) and spring-sapping and accentuated by a variable substrate geology. Sparks and West also identified a linear body of sand and gravel south of Blakeney which they interpreted as an esker, an interpretation that survives until the present (Gray, 1997;Moorlock et al, 2002;Gale and Hoare, 2007). However, Sparks and West (1964) recognised that the glacigenic deposits in the area were not formed during the last glaciation (MIS 2), and proposed that the landforms were formed during an earlier glacial stage, thus discrediting the morphostratigraphic concept of Newer and Older Drift.…”

“…To the north of the 'Cromer Ridge', further sands and gravels Lee, J.R., Phillips, E., Booth, S.J., Rose, J., Jordan, H.M., Pawley, S.M., Warren, M., Lawley, R.S. , 1964;Straw, 1973;Gray, 1997;Gale and Hoare, 2007). Although unconstrained by geochronology or lithostratigaphy, it is widely assumed that these lower units were deposited as ice retreated northwards from the 'Cromer Ridge'.…”

Marine Isotope Stage 7–6 transition age for beach sediments at Morston, north Norfolk, UK: implications for Pleistocene chronology, stratigraphy and tectonics

“…The earlier of the glacial episodes recorded at Morston is represented by the Marly Drift (unit 1 of Gale et al, 1988), a till that is the subject of considerable chronological debate (Gale and Hoare, 2007b). Straw (1965) noted the interdigitation of Blakeney esker sands and gravels with Marly Drift towards the north-western end of the esker (TG 017438) in the adjacent lower Glaven valley (see also Ehlers et al, 1987).…”

“…Straw (1965) noted the interdigitation of Blakeney esker sands and gravels with Marly Drift towards the north-western end of the esker (TG 017438) in the adjacent lower Glaven valley (see also Ehlers et al, 1987). If this interfingering is a primary feature of the stratigraphy, the Marly Drift and the complex assemblage of glaciogenic deposits, including those of the esker (Gale and Hoare, 2007b), outwash plains, kames and ridges, that dominate the Glaven valley, can be no younger than MIS 8. The preservation of beach sediments at Morston suggests that, with the exception of the Late Devensian ice sheet, whose progress was halted by the gently rising ground that characterises the coast hereabouts, the deposits have not been overrun by ice.…”

“…The Morston samples were separated vertically by only 0.508 m between 0 and 1 m OD, but are more widely spaced in the figure to avoid congestion of the Happisburgh Till) may date from MIS 12 (Pawley et al, 2008;Phillips et al, 2008). Hamblin et al (2000Hamblin et al ( , 2005 proposed a Briton's Lane Formation, comprising the sediments of the Cromer Ridge, the Blakeney esker and the Glaven valley kames (a correlation rejected by Gale and Hoare, 2007b, on lithological grounds) of MIS 6 date. This unit, apparently indicative of the glaciation of a substantial part of north Norfolk (Hamblin et al, 2005) left no trace in the Morston succession and failed to remove the beach sediments.…”