Book Review: Pedogenesis and soil taxonomy. L. P. Wilding, N. E. Smeck and G. F. Hall. Vol. I concepts and interactions; vol. II. The soil orders, 1983, Elsevier, US 49.00 and 55.25

Mineral Occurrence in Soil Environments

Micromorphology and development of loess-derived surface and buried soils along a precipitation gradient in Northern Iran

Mineralogical and clay mineralogical aspects of loess research

The mineral components of many soils are inherited almost exclusively from the parent material, but in others they have developed mostly in situ during the course of weathering and pedogenesis. In the majority of soils, the composition is a result of both inheritance and authigenic formation. Primary minerals are understood to mean those formed at high temperatures in igneous and metamorphic rocks, and secondary minerals are referred to those formed at lower temperatures in sedimentary rocks and soils. Primary minerals may have been subjected to one or more sedimentary cycles or have been components of previously existing soils. The proportion of secondary (authigenic) versus inherited (allogenic) minerals varies greatly among soils. Almost all the clay has developed in situ in some soils, but in others most of it is inherited. Soil sand and silt may consist entirely of primary minerals, but a significant portion of even these fractions.

Chapter 6 Composition and Soil Genesis

Clay mineral analyses were made of three groups of soil profiles — one developed from Peorian loess overlying Illinoian till — one associated with glacial till of Wisconsin age — one developed on deep to thin loess overlying Wisconsin till. These groups were investigated to determine the influence of parent material and intensity of weathering upon the soil profile development and clay mineral composition. Montmorillonite, illite, and chlorite are the dominant clay minerals in all the samples studied. In known loess samples, montmorillonite is invariably the most abundant clay mineral component. In the samples of unweathered till of Wisconsin age, illite and chlorite are the abundant clay minerals.

A. H. Beavers

Papers

Clay Minerals in Some Illinois Soils Developed from Loess and Till Under Grass Vegetation