Soil Distribution Patterns

With increasing time, soil oxidation intensity and oxidation depth, as well as the soil salt content, increase. Campbell and Claridge (1975) found that soil weathering indicated by these parameters could be expressed in terms of six soil weathering stages

Soil Weathering Stages

>3.5my

Fig. 2.5 Weathering stages identified in Antarctic soils by Campbell and Claridge (1975) are marked by increasing intensity and depth of oxidation and increasing soluble salt content. Weathering stage 5 soils may be Miocene or older judged by subsequent dating of volcanic ashes. k = 1,000 years; my = million years covering the time between late Last Glaciation and the Miocene (Fig. 2.5). These weathering differences are intimately associated with landform differences, most commonly moraine sequences of differing ages. Coupled with the soil age differences are soil differences resulting from climate. Soils in the oceanic subxerous and moist zones, for example, have comparatively high water contents, grading from around 0.5% in surface horizons to 12% near the permafrost boundary, while soils in the arid ultraxer-ous zones may have a moisture content of <0.5% through the whole profile. The soil salt content likewise shows a marked geographic distribution pattern, the coastal soils having salts dominated by sodium chloride, and the arid inland soils by nitrate salts.

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