DEVELOPMENT OF A FELDSPAR WEATHERING INDEX AND ITS APPLICATION TO A BURIED SOIL CHRONOSEQUENCE IN SOUTHEASTERN ENGLAND

An index of feldspar weathering (IFW) has been developed, based upon t he assignment of individual grains to weathering classes defined in te rms of progressive changes in surface morphology identifiable under a polarising microscope. The index was used to test the hypothesis that profiles of a (buried) paleosol developed on the higher terraces of th e River Thames in southeastern England are more weathered than those f ormed on lower and younger terrace surfaces. IFW, (ratio between the I FW of soil and parent material) and IFWD (difference between the IFW o f soil and parent material) values support a trend of increased weathe ring with assumed terrace age, although the pattern is less clear and conclusive towards the base of the terrace sequence. Anomalies in the dataset can be attributed to a range of factors including the possible variable composition and structure of the feldspars, the nature of th e parent material samples and probable fluctuations in soil processes and environments over time. Notwithstanding these problems, some of wh ich an specific to the study reported here, the technique and general approach clearly have more widespread potential for the (semi) quantit ative comparison of the relative weathering statuses of soils.