Plants and People, Including Students
The online edition of Deserts: Geology and Resources by A.S. Walker has much information on how and where deserts form, desert features, resources, and desertification-- the degradation of formerly productive lands. The greatest deserts were formed naturally over long periods of time. For the most part, deserts have grown and shrunk independent of human activities. However, in marginal areas, human activity may stress the ecosystem beyond its tolerance limit, resulting in degradation of the land. Learn more about desertification at this USGS website.
Visit the USGS Desertification web site
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Life, Death, and the Exploration of the Solar System
The mission of the SETI Institute is to explore, understand and explain the origin, nature, prevalence and distribution of life in the universe.
Visit the Center for Study of Life in the Universe web site
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