The purpose of this publication is to summarize the recent knowledge regarding the formation and significance of the great soil groups in the United States for the general reader. The treatment is in no sense complete or exhaustive. Attention is directed toward a discussion of those principles in broad implication. Should the reader require more specificity, the detailed reports of surveys and researches must be consulted.

This profusely illustrated book gives an exhaustive account of the principal types of soils of our planet. The "progressive descent of weathering fronts" model, recognized and used by eminent international scientists is the guiding principle of choice to link the observations and to give the reader a synthetic and coherent view of the differentiati