From the evidence presented in the previous chapters, the sequence of events in the Lower Thames Valley during the Pleistocene can be reconstructed. The stratigraphical scheme based on all the evidence available is summarised in Table 7 and will be discussed in chronological succession. Where possible, palaeogeographical reconstructions for each of the members are shown in Fig. 59.

Unless otherwise stated, each aggradational unit is separated by a phase of valley downcutting, from which, by definition, no deposits are preserved. As already mentioned, abandoned upper surfaces of aggradational units have, in almost all cases, been modified either by later sedimentation or degradation. The most common of these modifications resulted from periglacial processes and soil development.

In addition to the evidence presented above, fossil Mollusca from several sites in the study area have been investigated for the shell amino-acid content for chronological purposes. The aminostratigraphical technique is based on the principle that isoleucine initially present in shell protein in the L-configuration epimerises over geological time to its non-protein diastomer D-alloisoleucine. The ratios measured from the proportions of these two acids have been used directly for correlation and relative age ‘dating’. However, this correlation must be restricted to limited geographical areas that have experienced the same thermal history, since the epimerisation reaction is temperature dependent (Miller, Hollin & Andrews, 1979; Miller & Hare, 1980).