Several years ago the writer collected a series of sand samples from the shore of Lake Michigan, at Waverly Beach, about 10 miles west of Michigan City, Indiana. The samples were mechanically analyzed, and the data were used in a study of the probable error of sampling sediments for mechanical analysis (Krumbein, 1934). The paper was also presented at the Chicago meeting of the American Association for the Advancement of Science in June, 1933, at which time a map of the areal variation of average grain size was shown. The map itself was not published, however. During 1936 the writer, in collaboration with J. Scott Griffith (Krumbein and Griffith, 1938), studied the areal variation of beach deposits at Little Sister Bay, Wisconsin. The results of the latter study showed certain similarities to the earlier map prepared on the Waverly Beach samples, and the writer believes it pertinent to supplement . . .