Stratification of parent material in European volcanic and related soils studied by laser-diffraction grain-sizing and chemical analysis

Sedimentary stratification identified by field descriptions of 12 soils derived wholly or partly from volcanic materials was compared with results obtained by chemical analyses (contents and ratios of lithogenic elements, contents of heavy metals) and detailed grain-size data after removal of organic matter and amorphous fractions. The finest sedimentary stratification was indicated by cluster analysis of ratios of lithogenic elements and by the grain-size analyses. Sedimentary stratification in the field is difficult to determine or describe when (1) the deposits are strongly weathered, (2) soil horizon boundaries coincide with stratification boundaries or (3) stratification is very fine. Nevertheless, field descriptions are a reasonably good way of differentiating parent materials, though they often underestimate the number of sedimentary layers.