viii TABLE OF CONTENTS 



PAGES 



— Composition of glacial soils, 40 — Humus of glacial 

 soils, 41 — Glacial lakes, 42 — Lacustrine soils — glacial 

 lake, 43 — Lacustrine soils — recent lake, 44 — iEolian 

 soils, 45 — Loess soils, 46 — Distribution of loess, 47 — 

 Adobe soils, 48 — Sand dunes, 49 — Volcanic dust, 50. 



CHAPTER V 



Climatic and Geochemical Relationships of Soils . 65-82 

 Climatic relationships, 51 — Geochemical relationships 

 of residual and marine soils, 52 — Residual and glacial 

 soils, 53 — Effect of glaciation on agriculture, 54 — Hu- 

 mid and arid soils, 55 — Soil color, 56 — White and 

 black soils, 57 — Red and yellow soils, 58 — Agricul- 

 tural significance of color, 59 — Soil and subsoil, 60 — 



N^ Soil and subsoil of humid regions, 61 — Soil and subsoil 

 of arid regions, 62. 



CHAPTER VI 



The Soil Particle 83-107 



Soil separates and mechanical analysis, 63 — Princi- 

 ples of mechanical analysis, 64 — Mechanical analysis 

 by water in motion. Schone elutriator, 65 — Hilgard's 

 churn elutriator, 66 — Yoder's centrifugal elutriator, 67 



— Mechanical analysis by water at rest — Osborne's 

 beaker method, 68 — Atterberg's modified Appiani silt 

 cylinder, 69 — Centrifugal soil analysis, 70 — Classifica- 

 tion of soil particles, 71 — Bureau of Soils classification, 

 72 — Physical character of the separates, 73 — Mineral- 

 ogical characteristics of the separates, 74 — The chem- 

 ical constitution of soil particles, 75 — Value of a 

 mechanical analysis, 76 — Soil class, 77 — Determination 

 of class, 78 — The significance of texture and class, 79. 



CHAPTER VII 

 Some Physical Properties of the Soil .... 108-125 

 Arrangement of soil particles, 80 — The absolute spe- 

 cific gravity of the soil, 81 — Apparent specific gravity, 



