ABSTRACT
Soil classification is largely a 20th Century phenomenon although stirrings began in the preceding century. The program for a systematic soil survey of the US was launched in 1899 before any scheme for classification of soils had been devised in the country. This chapter describes two systems of soil classification used in the past and the one now being generally used in the US to illustrate what has been done and trends in the efforts. The early system of classification was a direct reflection of the prevailing concept of soil as the weathered mantle of rock, and the prevailing theory of soil genesis as rock weathering in place or as the deposition of weathered rock. The second system of soil classification in the US was based on a proposal by Marbut that was modified a few years after completion. The three categories in descending order were the physiographic province or region, the soil series, and the soil type.
