Soil science is perhaps one of the oldest practical sciences, having been of concern to man probably from the time he progressed from a strictly preda tory life to one in which agriculture became important. In view of the anti quity of concern with the subject, it is perhaps surprising that it can be approached from a fresh viewpoint, as is done in this book. Because soil science is an applied science, it is not surprising that the approach is usually descriptive, rather than imaginative. For agriculturalists and other land users, perhaps the most important part of soil science is the description of soils and the capacities of such soils to maintain crops, and this is reflected by the fact that soil science is usually treated ima highly descriptive manner, with soil classification being one of the main efforts. The treatment of the subject from a geological point of view, with considerable emphasis on the evolution of soils and the reasons governing their composition and form, makes this a highly readable book. Books on soil science are timely, with present-day concern with such major problems as the pollution of our environment and the possibility of overreaching our capacity for producing food for an expanding population.

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1. The Earth's Crust.- 1-1. Rocks and Minerals.- 1-2. Disequilibrium and Equilibrium.- 1-3. Alteration of Original Rocks by Weathering.- 2. The Weathering Environment.- 2-1. Fundamental Processes.- 2-2. Climate and Microclimate.- 2-3. The Five Variables of Weathering.- 2-4. The Steady State in Weathering.- 3. Geochemical and Pedochemical Weathering.- 3-1. Saprolites.- 3-2. Soils.- 4. Soil.- 4-1. Soil as an Entity.- 4-2. Soil Profiles.- 4-3. Mineral Products of Weathering.- 4-4. Residual Minerals of Weathering.- 4-5. Clay Minerals.- 5. Soil Patterns.- 5-1. Present-Day Soils.- 5-2. Classification of Soils.- 5-3. Soils of the United States.- 5-4. Lateritic Soils, Laterite, and Bauxite.- 5-5. Volcanic Ash.- 5-6. Loess.- 5-7. Sands.- 5-8. Alluvial Soils.- 6. Amount of Chemical Weathering.- 6-1. Calculating the Amount of Chemical Weathering.- 6-2. Barth's Calculations.- 6-3. Calculations from Chemical Analyses.- 6-4. Calculations from Mineralogical Analyses.- 6-5. Calculating the Amount of Clay Developed.- 7. Physical Weathering.- 7-1. Mechanical Disintegration.- 7-2. Primary Breakdown into Grains.- 7-3. Effect of Particle Size on Weathering Processes.- 7-4. Grain Sizes in Soils.- 8. Chemical Weathering.- 8-1. Weathering by Water.- 8-2. Kinds of Water in Weathering.- 8-3. Solution.- 8-4. Hydrolysis.- 8-5. Ion Exchange.- 8-6. Oxidation and Reduction.- 9. Biological Acivity in Weathering.- 9-1. Role of Plants and Animals.- 9-2. Ecology and Climatic Pattern.- 9-3. Organic Matter and the Formation of Humus.- 9-4. Humus in Soil Formation.- 9-5. Complexing and Chelation (Chevulation).- 9-6. Organic Weathering.- 10. Temperature in Weathering.- 10-1. Weathering Temperatures.- 11. Time in Weathering.- 11-1. Duration of Weathering Period.- 11-2. Pedological Indication of Time.-11-3. Fossil Soils.- 12. Trace Elements in Weathering.- 12-1. Amounts of Trace Elements in Rocks in the Lithosphere.- 12-2. Association with Minerals.- 12-3. Distribution in Granitic and Basaltic Rocks.- 12-4. Chemical Characteristics.- 12-5. Behavior of Trace Elements in Weathering.- 12-6. Petrographic and Biogeochemical Provinces.- 12-7. Relationship of Trace Elements to Plant and Animal Nutrition.- 12-8. Relationship of Trace Elements to Human Nutrition.- Appendix 1. Mineral Transformations in Weathering.- Appendix 2. Data of Rock Weathering.- Literature Cited.