W aTERE foremost distinction in geographic significance to be accorded to any of the light-colored great soil groups of the eastern United States, such recognition would be due the gray-brownerths.1 Their agriculture is of the greatest diversity: nearly every type of crop produced in the cooler middle latitudes is well represented. The high proportion of their area under cultivation is matched only by the richer dark-colored prairyerths and blackerths. The aggregate value of their crops approximates one quarter of the total annual value of all the crops of the United States. Other noteworthy relationships include the large number of farms operated by white owners, the high density of rural population, and the moderate amount of fertilizers used on these soils. Like all great soil groups, the gray-brownerths embrace soils in various states of development.2 A rather complete gamut ranging from infancy to senescence may be discerned, but for simplicity only three broad categories, mature, immature, and abnormal types, will here be recognized.