Soil development on Proterozoic and Paleozoic rocks of central Bohemia

Abstract

The character of modern pedogenesis in the territory of the Brdská and Křivoklátská vrchovina Highlands was studied on silicate rocks such as Paleozoic granite and Proterozoic mudstone and greywacke. The parent materials were evaluated on the basis of petrography, X-ray diffractometry of powder samples of rock forming and heavy minerals. The soils were described as for their macromorphological characterics and the results of a variety of analyses of organic and anorganic components. Pedogenesis proceeded in acid conditions. The values of base saturation are mostly below 50 % for the Ah horizons. The intensity of soil development on individual parent material decreases in the order: mudstone (Ah-AhBw-Bw-C)granite (Oi-Oe-Oa-Ah-Bw-C)greywacke 1 (Oi-Oe-Oa-Ah-AhC-C)greywacke 2 (Oi-Oe-Oa-Ah-C). The process of humification was documented at all study sites. Evidence of pedogenetic alteration is present in soils developed on granite and mudstone. High amounts of chlorite and elevated contents of illite are characteristic for Cambic Leptosols (Dystric, Skeletic) on mudstone. Weddellite and whewellite were found in relatively large amounts in O horizons of soils except for the Červený kríž site. The predominant from of calcium oxalate minerals at these sites is whewellite. Weddellite occurs in small amount, which is probably due to its lower stability.