DISSERTATION RESEARCH: Vesicular soil horizons - the fragile skin of desert soils: Their distribution, formation processes, and relation to surface hydrology in the western U.S.A.

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Soils found in dry parts of the Earth, including large areas of the western United States, that have a layer of distinctive bubble like pores at or near the soil surface, are called vesicular soils. These layers are relatively thin, usually less than 10 cm, but can act as a water repellent skin that determines whether water infiltrates, runs off, or evaporates from the soil surface. Plans for solar and wind power facilities in the deserts of the southwest have raised concern about increased soil disturbance in previously undeveloped lands. The formation of these soils is still a mystery. This project will evaluate the formation of vesicular layers in deserts, including their distribution, formation and relation to soil water movement. An index will be used to quantify the relative development of the layers. The study also considers new ways to explain the formation of vesicular pores, such as modeling their expansion using basic chemical principals relating the temperature and volume of gases. The study will include analyses of soil data bases, laboratory experiments and field studies. One new approach will be to use high resolution CAT scans to look inside soil samples and examine the size and shape of the pores without disrupting soil structure. Results will be presented at professional meetings and in high school classes. Results will also be used in a proposal for the formal recognition of vesicular soils. Management of arid lands is at a critical moment right now, with plans for extensive energy facilities under development and review. Since the vesicular layer is a fragile surface that is highly susceptible to erosion by wind and water when it is disturbed, adoption of this terminology will increase awareness and highlight management options for the arid west.