Some Geographic Aspects of the Seventh Approximation

Abstract

The Seventh Approximation sharpens the relationship between soil classification and soil geography; and it is likely to lead to more valid geographic correlations between genetic factors and soil morphology. Although the Seventh Approximation is expected to bring about only a few changes on large-scale, detailed soil maps, the opposite is true for small-scale, general soil maps. Even on the general maps, however, many, perhaps most, soil boundaries will appear where they would have appeared using the current soil classification; but the changes will be drastic in the nomenclature. The fact that substantive names are, or will be, provided for all classes in all categories makes soil classes of all categories available for use on maps. This fact makes possible a better matching of categorical and cartographic levels of generalization. The Seventh Approximation does not alter the need for the concepts of soil phases and soil associations.