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 

 (e.g., 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 0.42 millimeter though it varied from 

 0.30 millimeter at profile line 9 to 0.68 millimeter at profile line 13. The 

 median for individual samples varied even more, from 0.15 to 1.05 millimeters. 

 The average range in median foreshore sand size between profile lines was 0.30 

 millimeter. 



Backshore samples were more uniform and finer. Average median sand size 

 was 0.29 millimeter (0.13 millimeter less than the foreshore), varying only 

 from 0.24 millimeter at profile line 13 to 0.36 millimeter at profile line 

 1. The range in average median size of backshore samples (0.11 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 sample consists of about 24 

 percent gravel, 76 percent sand, and less than 1 percent silt. The backshore 

 contains only 2 percent gravel, 84 percent sand, and 14 percent silt. Actual 

 samples similar to these are shown in Figure 16. 



31 



