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SOIL FORMATION

A. INTRODUCTION

• Chapter 12 pp. 353-359 and 367-368


• development of soil profile (layers)
  
  
• development of soil characteristics

B. THE SOIL PROFILE

• O horizon: litter layer; forested areas
  
  
• A horizon: top soil; high organic content
  
  
• E horizon
  
  
  • eluviation of clay, iron, aluminum
    
    
  • sand & silt left behind
    
    
• B horizon
  
  
  • illuviation: accumulation of eluviated materials
    
    
• C horizon: unconsolidated parent material
  
  
• R horizon: solid rock

C. FACTORS AFFECTING SOIL FORMATION

Parent material (geology)

• rock that has weathered in place to form a soil

• material transported from elsewhere, deposited, and weathered to form a soil

Organisms (biology)

Climate

• temperature

• moisture

Topography (relief)

• slope gradient

• slope orientation (N-S-E-W)

Time (chronology)

D. SUMMARY

• Parent material, organisms, climate, topography & time interact
  
  
• Soil profile develops
  
  
• Characteristics change: composition, color, texture, structure, soil water, chemistry