CONTENTS 



CHAPTER PAGE 



I. SOIL MATERIAL AND ITS ORIGIN 1 



Definition of Soil Elements of the Earth's Crust Soil 

 Forming Minerals Rocks Igneous Rocks Aqueous 

 Rocks Metamorphic Rocks. 



II. WEATHERING 11 



Physical Agencies Heat and Cold Freezing and Thaw- 

 ing Glaciers Erosion of Streams Waves Wind 

 Plants Chemical Agencies Acids Carbon Dioxide 

 Oxidat ion Deoxidation Hydration Solution Plants 

 Animals. 



III. THE PLACING OF SOIL MATERIAL. I. RESIDUAL, GRAVITY- 



LAID AND WATER-LAID DEPOSITS 27 



Sedentary Formations Residual Soils Cumulose Soils 

 Swamps and Marshes Transported Formations Col- 

 luvial or Gravity-laid Soils Sedimental or Water-laid 

 Soils. 



IV. THE PLACING OF SOIL MATERIAL. II. GLACIAL OR ICE-LAID 



DEPOSITS 41 



The Glacial Period The Jerseyan or Nebraskan Glacia- 

 tion The Kansan Glaciation The Illinoisan Glaciation 

 The'Iowan Glaciation The Early Wisconsin Glaciation 

 The Late Wisconsin Glaciation Incidental Features. 



V. THE PLACING OF SOIL MATERIAL. III. EOLIAL OR WIND- 

 LAID DEPOSITS . 53 



Classes of Wind-laid Material Dunes Loess Adobe 

 Volcanic Dust. 



VI. SOIL AND SUBSOIL 67 



The Top Soil Surface Subsurface Subsoil Tight Clay 

 Hard Pan Humid and Arid Subsoils Plow Sole. 



VII. CLASSIFICATION OF SOILS 72 



Need of Classification Basis of Classification Geological 

 Lithnlngicnl Tem|>eraturc- Moisture Arid Soils 

 Humid Soils Vegetation Color Texture. 



VIII. CLASSIFICATION nv THE BUREAU OF Soius 78 



Soil Province Soil Region Soil C'lass -Soil Type Pied- 

 mont Plateau Province Appalachian Mountain and Pla- 

 teau Province -Limestone Valleys and Uplands Province 

 Glacial and Ix>essial Province Glacial Lake and River 

 Terrace Province Atlantic and Gulf Coastal Plains 

 Province River Flood Plains Province Great Plains 

 Region Rocky Mountain and Plateau Region North- 

 western Intermountain Region Great Basin Region 

 Arid Southwest Region Pacific Coast Region. 



