to finer grain sizes as one moves seaward. Only Stations 3, 6, and 7 exhibit 

 a coarse fraction. 



Use of Composites 



47. To reduce the variability between the large number of samples in 

 this data set, a mathematical composite was constructed from the individual 

 weight percent data of each sample group. The composites were assembled by 

 combining all the samples from each group to form a single composite sample of 

 the (a) dune, (b) beach, (c) bar/trough, and (d) nearshore for a given sample 

 day (Figure 11) . Another composite was constructed using all the samples 

 across the profile to make a profile composite for each sample day. To con- 

 struct the composite, ISAP was used to combine the percentage of sediment in 

 each 1/4-phi-size class of the different samples in each composite group, and 

 a new average grain-size distribution was calculated. This method, described 

 in Hobson (1977) , preserves the grain-size information of each individual sam- 

 ple for later use and allows for various combinations of composites. Each 

 composite frequency curve was then plotted, and the sediment statistics were 

 calculated. 



48. A plot of the composite means versus sorting of each sample day is 

 shown in Figure 23. By reducing the number of data points and averaging the 

 data in each group, a clearer picture of the cross-shore grain-size distribu- 

 tion is shown. The trend of finer grain sizes in the offshore direction is 

 shown. The trend of best sorting in the dune and the nearshore group sedi- 

 ments and the poorest sorting or widest spread in individual grain sizes in 

 the beach and nearshore groups can clearly be seen. Within the cross -shore 

 spatial distribution, overlap was only minimal, with each group having a spe- 

 cific range of means and sorting. Within each sediment group, the spread in 

 data points can be correlated with coarser, more poorly sorted sediment dis- 

 tributions occurring after higher wave events and the finer, more well- sorted 

 sediment distribution occurring during low wave periods. 



49. With the irregular spacing of survey data collection, temporal 

 trends and variations can be interpreted only in general terms. Only two 

 storm events were closely bracketed. The other sampling periods average the 

 daily change over longer time spans. Plots of the composite grain-size fre- 

 quency curves through time for each cross -shore sediment group are shown in 



58 



