Approaches to the study of the lithological homogeneity of soil profiles and soil polygenesis

A methodology for the analysis and diagnosis of soil polygenesis is discussed. It is based on the successive and complementary stages of soil examination: (1) the field stage, during which the morphological analysis of a soil profile is combined with the study of the spatial behavior of the major soil horizons in order to reveal the degree of their genetic interdependence or their stratigraphic independence and (2) the stage of the careful morphological description of the soil profile at different levels (from the macrolevel to the micro- and submicrolevels) by the methods of soil morphology in combination with the methods of paleogeography, mineralogy, cryolithology, microbiomorphology, and other sciences. As a result, we distinguish between the modern and relict (inherited) soil features; the latter are subdivided into the lithogenic soil features (lithorelics) and pedogenic soil features (pedorelics, traces of the former stages of the soil development). Two groups of models of soil polygenesis can be distinguished: (1) simple models, according to which the changes in the character of the pedogenesis and in the environmental conditions are recorded in the same lithological matrix, and (2) complex models, according to which the changes in the cycles of the soil formation are complicated by the processes of sedimentation so that they are recorded in the changing lithological matrix.