. Coastal changes, eastern Lake Michigan, 1970-1974. Coast changes. Figure 14. The beach at profile line 2, showing the wide range of sediments (May 1973). Note bands of pebbles on the foreshore and heavy minerals along the backshore. Because of the varied nature of the sediments and the difficulty in collecting truly representative samples, the data were interpreted by simple averaging of the sediment data by month and by profile. To eliminate any seasonal bias in the results, annual averages were computed for each profile line by first computing an average for all the samples from the same m
. Coastal changes, eastern Lake Michigan, 1970-1974. Coast changes. Figure 14. The beach at profile line 2, showing the wide range of sediments (May 1973). Note bands of pebbles on the foreshore and heavy minerals along the backshore. Because of the varied nature of the sediments and the difficulty in collecting truly representative samples, the data were interpreted by simple averaging of the sediment data by month and by profile. To eliminate any seasonal bias in the results, annual averages were computed for each profile line by first computing an average for all the samples from the same month (, October 1973 and October 1974) and then by averaging the 12 monthly averages. Table 5 summarizes the sediment statistics for each profile line. An examination of the median sand size revealed that the foreshore was coarser than the backshore in 92 percent of the available foreshore-backshore sample pairs. This is obvious in Figure 15, which is a histogram of the median sand sizes given in Table 5. The median size of the backshore samples varied more smoothly alongshore than did the foreshore samples. The average median sand size for the foreshore was millimeter though it varied from millimeter at profile line 9 to millimeter at profile line 13. The median for individual samples varied even more, from to millimeters. The average range in median foreshore sand size between profile lines was millimeter. Backshore samples were more uniform and finer. Average median sand size was millimeter ( millimeter less than the foreshore), varying only from millimeter at profile line 13 to millimeter at profile line 1. The range in average median size of backshore samples ( millimeter) was less than the range for the foreshore samples. Though it seldom actually occurred, an idea of the typical composition of foreshore and backshore sediments is given in the line of average values at the bottom of Table 5. A composite foreshore sa
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