Graphic methods of presenting sedimentary data, and the statistical analysis of the data, are presented from two points of view: one, in which the analytical data are considered in terms of discrete classes, as gravel, sand, silt, and the like; and the other in which the data are considered as a continuous frequency distribution of sizes, independently of the grade scale used in the analysis. Methods of presentation, description, and comparison of sediments are discussed in some detail, but particular attention is paid to the problem of choosing convenient mathematical methods for the simplification of the statistical treatment. These methods involve the substitution of new independent variables for diameters in the mathematical treatment, in such a manner that the geomet ical picture of the data is not destroyed. Finally, the theoretical implications of the newer approach are pointed out.