Abstract

Palaeosols (fossil soils) are a major component of alluvial deposits in the geological record. Not only do these typically show considerable variations in their degrees of development within single formations, but they also exhibit highly complex stratigraphic relationships with one another. A simple quantitative approach to these variations is presented which provides a graphical means of assessing differences in soil (palaeosol) development within a sequence with calcic or petrocalcic horizons. To illustrate the approach, a range of palaeosols from the Siluro-Devonian (Old Red Sandstone) of Britain are characterized in terms of the likely frequency and magnitude of depositional events which occurred during their formation. In particular, two alluvial suites from the Manorbier area of South Wales are analysed using this approach. The technique should be widely applicable to other alluvial successions and provides a means of graphicallv presenting relationships between multiple palaeosols, although the wide range of rates of formation of calcic and petrocalcic horizons precludes their use to provide narrow estimates of deposition rates.