The influence of mineralogical composition, electrical conductivity and pH on the rheological properties of Latvian illite clays has been investigated. Samples from two deposits have been studied. The average plasticity index of samples from both Laza deposits is 23-25, but from Apriki - around 20. Based on these results, 2 sample s with different plasticity indices from each borehole were chosen for further research. All suspensions exhibityield-pseudoplastic behavior. Samples with the highest amount of clay minerals have the highest plasticity index and apparent viscosity. From 3 samples with similar amount of clay minerals and plasticity index one sample has higher pH and electrical conductivity and therefore exhibits lower viscosity., Inga Dusenkova, Valentina Stepanova, Jana Vecstaudza, Vitalijs Lakevics, Juris Malers and Liga Berzina-Cimdina., and Obsahuje bibliografické odkazy
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., Anna Žigová, Martin Šťastný, Petr Mikysek., and Obsahuje bibliografické odkazy