On a global scale, the soil represents just the skin of the Earth. This thin layer, however, is critical to the functioning of the hydrological cycle, the sustainability and adequacy of food production, and the maintenance of a quality environment. Soil functions are frequently split into biological, chemical, and physical components to ease study and understanding. Daniel Hillel develops the physical aspects of the soil in its broadest sense in this latest textbook, Environmental Soil Physics , which updates and expands his earlier works.