Although it is the chief purpose of the author to outline and discuss the system of classification proposed by the late Dr. C. F. Marbut as adapted to American soils, it is well to briefly review the fundamentals and earlier systems as a background. Many systems which have been proposed are too technical to have much practical value, while others are too simple to have much scientific value. It seems, therefore, that if the following fundamentals are considered, both requirements may be met