. Bulletin of the British Museum (Natural History), Geology. OF BRITISH ISLES. Fig. 3. Location map of rodent localities in the Thames estuary and the Lea valley. Secondly, there are terraces of the Lower Thames, including Swanscombe, Clacton, Ilford, Aveley and Grays, Crayford and Erith. Hinton (1926b : 126-131) classified these as the High Terrace of the Thames (Swanscombe), the Early Middle Terrace (Grays Thurrock), and the Late Middle Terrace (Crayford and Erith). Whereas each terrace of the upper part of the river is of approximately constant height above the present-day bed of the river
. Bulletin of the British Museum (Natural History), Geology. OF BRITISH ISLES. Fig. 3. Location map of rodent localities in the Thames estuary and the Lea valley. Secondly, there are terraces of the Lower Thames, including Swanscombe, Clacton, Ilford, Aveley and Grays, Crayford and Erith. Hinton (1926b : 126-131) classified these as the High Terrace of the Thames (Swanscombe), the Early Middle Terrace (Grays Thurrock), and the Late Middle Terrace (Crayford and Erith). Whereas each terrace of the upper part of the river is of approximately constant height above the present-day bed of the river and thus becomes progressively lower as it is followed downstream, these terraces of the Lower Thames (which are related to former high sea levels) have approximately horizontal aggradation surfaces and they do not extend further upstream than the head of the contemporary tidal limit of the river. All are of interglacial or interstadial age and they can be cor- related with raised beaches of similar heights along the open coastline. The cold stages which occurred between the accumulation of these terraces of the Lower Thames are represented by deposits submerged in the buried channels of the present- day river, previously mentioned. Thirdly there are solifluxion and hillwash deposits, the heights of which are un- related to the terrace system, with the deposits of which they are often interbedded. Northfleet is the only rodent locality, probably of this category, known to the writers. It follows that, in an area as complicated as the valleys of the Rivers Thames and Lea, the exact relationship between the various rodent-bearing deposits is difficult to interpret. The literature on this subject, which goes back for nearly a century and a half, is voluminous. The general sequence was discussed by King & Oakley (1936) and in a number of important papers by Zeuner ( 1954), who produced a schematic section from the Ebbsfleet Valley to Swanscombe, Kent, showing his interpreta
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