Figure 24. Using the entire distribution from the coarse to fine sizes shows 

 the details of change by grain-size class, in depositional regimes. The dune 

 composite distributions show little change through time. The slight change in 

 percentages in each grain- size class is due to sampling within the vegetated 

 dune. Coarse shifts in the curves are due to collection of coarse shell mate- 

 rial. The highest variability in distribution was found in the beach group 

 composites. The bimodal nature of the distribution can be seen, with 

 increases in the coarse mode fraction after storms or when samples on the 

 foreshore contained granule-size lag deposits. The coarsest material was 

 present early in the study period during the winter storm period. Later beach 

 distributions showed a shift to the finer mode, except during July 1985 when a 

 coarse fraction was present. The bar/trough group showed a more unimodal 

 distribution that was more uniform through time. Again, a coarse component 

 was present during the winter of 1984/85 sampling, that was not there during 

 the later sampling periods during the summer of 1985. Little change can be 

 seen in the nearshore distribution throughout the entire study period, with 

 only a slight percentage of coarse material appearing in the winter months. 

 Note the small percentage of coarse material that occurred after the 

 11-13 October 1984 and the 3-5 January 1985 storms and disappeared into the 

 summer months . 



50. A temporal summary in the grain-size distribution was constructed 

 by creating a profile composite, averaging all 17 individual cross -prof ile 

 samples for each sample day into one mathematical composite. Details of the 

 cross -shore differences are smoothed, and variations are reduced with this 

 procedure, but the main trends are more prevalent. Figure 25 showed the pro- 

 file composite frequency curve grain-size distributions through time as well 

 as the mean grain size versus sorting. This use of a profile composite shows 

 the change from a flatter frequency curve that had a coarse mean and poor 

 sorting and higher percentage of the coarser grain sizes during the winter to 

 a smoother bell-shaped curve in the summer. The well-sorted coarse distribu- 

 tion of 11 August 1984 resulted because no samples were collected below NGVD 

 that sample day. The general trend in grain- size distribution variation is 

 characterized by the change in the coarse fraction. The finer fraction, owing 

 to the large number of samples in the bar/trough and nearshore regions, 

 remained the dominant percentage of this profile composite. 



60 



