The Glaciation of the London Basin and the Evolution of the Lower Thames Drainage System

Abstract

The superficial deposits of the London Basin fall broadly into three groups on a basis of elevation and age. The highest and oldest deposits include marine sand and shingle of Pliocene age, and also the Pebble Gravel, which is younger than these marine deposits, though most workers have agreed that it is pre-glacial, in the local sense. At somewhat lower elevations are hill and plateau gravels, associated north of London with undoubted glacial deposits. Finally, at the lowest levels we have the terrace and valley gravels of the Thames and its tributaries. It is apparent that these superficial deposits constitute a record which should enable us to trace the stages of development of the existing surface features of the area. The oldest group of deposits (Pliocene beds and Pebble Gravel) were accumulated before any of the existing valleys were excavated, forming thus, in an essential sense, constituents of the “solid geology” of the area. The valley and terrace drifts reveal a drainage system agreeing in all essential features of plan with that of the present day. The long period of time representing the important “middle term” of our three-fold series proves to be critical for two main reasons. It witnessed the appearance of ice-sheets on at least one and probably two occasions. During the same period the course of the lower Thames shifted from far north of the centre of the basin to the neighbourhood of its present course. The following communication is an attempt to elucidate these important events

Late Cenozoic uplift of the Amanos Mountains and incision of the Middle Ceyhan river gorge, southern Turkey; Ar–Ar dating of the Düziçi basalt

“…2 and 4; Sections 4.1 and 4.2), evidently reflecting 'uniclinal shifting' (cf. Wooldridge, 1938) of the river. For instance, the diversion associated with the volcanism in MIS 9b evidently involved a westward 'shift' of the outlet from Berke Gorge into the pre-existing valley of the River Keşiş (Fig.…”

Early-Middle Pleistocene Beheading of the River Thames

“…White (1897) enthusiastically endorsed Davis' deductions as support for his own view that Triassic debris on the Cotswolds dipslope was of fluvial rather than glacial origin. Some decades later Wooldridge (1938), the dominant personality in Thames studies for forty years, invoked Davis' Cotswold paper and his concept of river capture to support his views on another Thames problem: whether or not that river always flowed through the Vale of St. Albans until its deflection by an ice sheet (Fig. 2a).…”

“…Wooldridge (1955, p. 90) remained "heavily in debt to Davis" and resented the criticism levelled at him. But, in both his Thames work and in his wider analysis of landscape development in southeast England (Wooldridge andLinton, 1939, 1955) Wooldridge has been shown to be in error by later workers (e.g. Hey, 1965;Hodgson etal, 1974;Catt and Hodgson, 1976;Gibbard, 1977;Green and McGregor, 1978;Rose, 1983;Allen etal., 1991), who addressed the problems largely from a sedimentological and lithological standpoint.…”

Volcanic pebbles in Pleistocene gravels of the Thames in Buckinghamshire and Hertfordshire

“…At Coldharbour near Goring, Hawkins (1923) reported dark grey and pinkish rhyolites from a deposit thought by him to be a till. Treacher, Arkell & Oakley (1948) noted the presence of volcanic rocks in the Lower Gravel Train of Wooldridge (1938), and Wooldridge (1958) described basalt and flow banded rhyolite from a deposit at Mardley near Welwyn. Wooldridge regarded this deposit as part of an early till (his Chiltern Drift).…”