The 1938 USDA soil taxonomy was a soil classification system adopted by the United States Department of Agriculture, now obsolete. The classification system used previously was developed and published in 1936 by C.F. Marbut, who was chief of the U.S. Soil Survey at that time. A drastic modification, the 1938 system was extensively revised in 1949 and remained in use until 1965. See USDA soil taxonomy for the current system.
The 1938 soil taxonomy divided soils between three orders dependent on dominant soil forming factors.
Intrazonal soils have more or less well-defined soil profile characteristics that reflect the dominant influence of some resident factor of relief or parent material over the classic zonal effects of climate and vegetation. There are 3 major sub-types, 2 of which have 2 further sub-types each.