Soils, Watershed Processes, and Marine Sediments

David R. Montgomery, Darlene Zabowski, Fiorenzo C. Ugolini, Rolf O. Hallberg, and Henri Spaltenstein 

Soil is a key component of the rock cycle because weathering and soil formation processes transform rock into more readily erodible material. Rates of soil formation may even limit the overall erosion rate of a landscape. Erosion processes are also a key linkage in the rock cycle 

Copyright ( 2000 Academic Press Limited All rights of reproduction in any form reserved 

In arid environments, where the soluble products of weathering are not completely removed from the soil, saline solutions may circulate in the soil as well as in rock fractures. If upon evaporation the salt concentration increases above its saturation point, salt crystals form and grow (Goudie et al, 1970). The growth of salt crystals in crevices can force open fractures. Salt weathering occurs in cold or hot deserts or areas where salts accumulate. Boulders, blocks. 

Thermal expansion induced by insolation may be important in desert areas where rocky outcrops and soil surfaces are barren. In a desert, daily temperature excursions are wide and rocks are heated and cooled rapidly. Each type of mineral in a rock has a different coefficient of thermal expansion. Consequently, when a rock is heated or cooled, its minerals differentially expand and contract, thereby inducing stresses and strains in the rock and causing fractures. Ollier (1969) discussed examples of rock weathering due to insolation. Fire can develop temperatures far in excess of insolation and be quite effective in fracturing rocks (Black-welder, 1927). 

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Montgomery, D.R., Zabowski, D., Ugolini, F.C., Hallerg, R.O., and Spaltenstein, H. (2000) Soils, watershed processes, and marine sediments. In Earth System Science,... 

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