The clay mineralogy and chemistry of some soils from the Ross Dependency, Antarctica

Abstract

The clay mineralogy, soluble salts, and calcium carbonate content of some soils from the Ross Dependency are discussed in terms of a tentative classification and in an attempt to elucidate the nature of the soil processes operating in the Antarctic. The soils are classified on the basis of their parent material, and on the age of the surface on which they are formed. It was found that both physical and chemical weathering are important in the soil processes of the Antarctic. Physical weathering is responsible for the breakdown of the parent rock and includes breakdown by freeze and thaw processes, wind abrasion, and glacial action. The presence of considerable chemical weathering is shown by the formation of iron stains on rocks, the formation of crusts of calcium carbonate and gypsum, and the presence of clay minerals such as montmorillonite, which have formed in environments rich in calcium and magnesium. The degree of chemical weathering, and the nature of the clay mineral found are related to the age of the soil. The soils of the Antarctic can be compared with soils of alpine regions elsewhere in the world, but show greater similarities with the soils of the cool-temperate semi-arid regions of Central Otago in New Zealand. They were formed under more extreme conditions than those of Arctic regions, in terms of temperature and aridity, and in particular in the almost complete absence of plant life. The zonal soil of Antarctic regions, or frigic soil, is defined and described in terms of the New Zealand soil classification.