R. G. West & P. L. Gibbard write: The recent report 'Excavations at the Lower Palaeolithic site at East Farm, Barnham, Suffolk 1989-92' (Ashton et al. 1994a) is welcome in providing initial results of a multi-disciplinary study of an important Lower Palaeolithic site, where local stratigraphy has provided a framework in which to place biostratigraphical and archaeological data. We wish, however, to discuss the question of dating of the temperate silts in the part of the paper entitled ‘Dating’. This relates temperate faunally-rich silt and clay at Barnham to Stage 11 of the global marine Quaternary stratigraphy based on Oxygen Isotope Stages (Shackleton & Opdyke 1973). The problem concerns the application of amino-acid analysis (AA) of mollusc shells, in particular D-alloisoleucine/L-isoleucine epimerization rates, to regionally established biostratigraphical and lithostratigraphical sequences.
Amino-acid geochronology has made a major contribution to Quaternary stratigraphy, especially because it is a method which is applicable to freshwater and marine faunas, of age greater than those suitable for radiocarbon-dating. In the present case, there is a marked discrepancy between the present state of East Anglian regional stratigraphy (Table 1 and Ehlers et al. 1991, table 41) and the correlation of the Barnham sediments with the global marine stratigraphy. The former says that the cold Anglian Stage, the latest part of which included the most widespread glaciation represented by Lowestoft Formation till (chalky boulder clay) in East Anglia, is succeeded by the temperate Hoxnian Stage. This stage is typified by the lacustrine sediments filling an enclosed depression in