Archaeological and historical evidence for subsidence in southern Britain

Abstract

This paper is presented as a warning of the pitfalls which are involved in a too ready and uncritical acceptance of the evidence for apparent changes in relative land and sea level which has been derived from the archaeological and historical remains around the coasts of southern Britain. The general trends of relative sea level changes in the later Holocene are indicated; but I am concerned more to correct some of the misapprehensions and inexact conclusions which have been drawn from the often imprecise data, and to establish a wider recognition of the types of errors and inaccurate assumptions which have been promulgated in some publications, and which erroneously, albeit unwittingly, have been cited by specialists in other disciplines to reinforce or to substantiate conclusions derived from their different data. The optimum conditions for establishing the former positions of relative mean sea level are found in deposits which can be shown to have formed in a known relationship to sea level as part of a continuous halosere from marine sands and clays to freshwater fen deposits (cf. Churchill 1965, p. 240). I would stress that estimates of sea level changes should be based primarily on the analysis of physiographical data; the archaeological and historical data may provide complementary and corroborative evidence of relative land and sea level changes, but they are generally too imprecise to stand alone as definitive indicators of actual mean sea level or tidal heights.