TABLE OF CONTENTS. 



PREFACE xxiii 



INTRODUCTION, xxix. Definition of Soils, xxix. Elements Constituting the 

 Earth's Crust, xxix. Average Quantitative Composition of the Earth's 

 Crust, xxix. Clarke's Table, xxx. Oxids Constitute Earth's Crust, xxx. 

 Elements Important to Agriculture ; Table, xxxi. The Volatile Part 

 of Plants, xxxii. 



CHAPTER I. 



AGENCIES OF SOIL FORMATION, i. i. Physical Agencies, i. Effects of 

 Heat and Cold on Rocks, i. Unequal Expansion of Crystals, 2. Cleav- 

 age of Rocks, 3. Effects of Freezing Water, 3. Glaciers ; Figure, 3. 

 Glacier Flour and Mud, 4." Green" and "White" Rivers, 4. 

 Moraines, 5. Action of Flowing Water, 5. Enormous Result of Cor- 

 rasion and Denudation, 6. Effects of Winds, 8. Dunes, 8. Sand and 

 Dust Storms in Deserts, Continental Plateaus and Plains, 8. Loess of 

 China, 9. Migration of Gobi Lakes, 9. Classification of Soils, 10. 

 Their Physical Constituents, 10. Sedentary or Residual Soils, n. 

 Colluvial Soils, 12. Alluvial Soils. Diagram, 12. Character of these 

 Soil Classes, 13. Richness of Flood-plain and Delta Lands, 14. Low- 

 ering of the Land Surface by Soil Formation, 15. 



CHAPTER II. 



CHEMICAL PROCESSES OF SOIL FORMATION, 16. 2. Chemical Disintegra- 

 tions or Decomposition, 16. Ingredients of the Atmosphere, 16. Effects 

 of Water ; of Carbonic Acid, 17. Carbonated water a universal solvent, 

 17. Ammonic carbonate, effect on silicates, 18. Action of oxygen ; on 

 ferrous compounds, 18. Action of Plants and their Remnants, 19. A. 

 Mechanical ; Force of Root Penetration, 19. B. Chemical ; Action of 

 Root Secretions, 19. Bacterial Action, 20. Humification, 20. Causes 

 Influencing Chemical Action and Decomposition, 21. Heat and Mois- 

 ture, 21. Influence of Rainfall on Soil-Formation, 22. Leaching of the 

 Land, 22. Residual Soils, 22. Drain Waters ; River Waters. Tables 

 of Solid Contents, 22. Amount of Dissolved Matters Carried into the 

 Sea ; Amount of Sediment, 24. Sea Water, Composition of ; Waters of 

 Land-locked Lakes, 25. Results of Insufficient Rainfall ; Alkali 

 Lands, 28. 



V 



