Lithological discontinuities in Podzols developed from sandstone cover beds in the Stolowe Mountains (Poland)

Abstract

Podzols developed within so-called cover beds were examined on a slope built of Cretaceous sandstones in SW-Poland. Their typical feature is an easily recognizable stratification of regolith, evidenced in the dichotomy of soil texture and dense subsoil. Heterogeneity of soil profiles is manifested in vertically differentiated sequence: (1) dense, skeletal and massive layer, comprising usually Bs and BC horizons, sometimes Bhs/Bh horizons with strong platy structure is overlain by (2) the uppermost, relatively young layer, consisting of loose sandy material, bearing single coarse fragments of a less weathered sandstone, hosting AE, E and partially Bh horizons. This remarkable layering of slope sediments caused a distinctive lithological discontinuity at the boundary of E and B horizons, evidenced by the differences in: (i) rock fragments' content, (ii) degree of rock clast weathering, (iii) distribution of highly resistant minerals, and (iv) fluctuation of silt and sand fractions within profiles. Lithological discontinuity influences both the lateral podzolization, and the thickness and depth of albic and spodic horizons along the slope catena. Regarding the temporal order, the lowermost layer was influenced by periglacial conditions at before the Boreal; presumably as the surface layer (high score of pollen grains). The age of surficial sandy layer (based on pollen record) could be established at Subatlantic and correlated with forest cutting and intensive surface erosion (charcoal dating: 960+/−30calBP). Neither layers that originated from the eolian processes were distinguished nor any admixture of allochthonous material was found, therefore “typical” middle and upper periglacial cover-beds are not present in this sequence. In any case, Podzols that were formed from the slope sediments in the Stolowe Mountains are polygenetic and of the Holocene age.