mean distances from shore; the first bar was less than mean depth and the 

 second was 1 foot more than the mean. Location and depths of bars were 

 much like that observed the summer of 1969 (Davis and Fox, 1971) . Ephem- 

 eral bars are fairly common and the beach was quite wide. All of these 

 were contributing factors in preventing waves from attacking the adjacent 

 dunes and keeping erosion restricted to the beach. 



q. Profile Site 17 . This is one of the most severely eroded sites; 

 190 cubic feet of sediment was lost. The nearshore profile provides 

 adequate data to explain this erosion. The slope adjacent to the beach is 

 relatively steep and both permanent bars are the deepest and farthest from 

 shore of all the study sites (Table 6) . There was little to impair wave 

 energy from reaching the shore and removing sediment. 



VIII. BEACH SEDIMENTS 



Beach sediments were collected and analyzed for textural parameters 

 in conjunction with the profile surveys. Samples were collected during 

 each site visit to determine if there were any patterns (spatial or tem- 

 poral) to the distribution of beach textures. Foreshore sediments were 

 also collected to test the validity of the grain-size slope relationships 

 described by Bascom (1964) and Shepard (1972) . 



1. Collection and Analysis of Sediments . 



Samples were collected from the backshore and foreshore at each site 

 during all visits except when ice cover was so thick that the beach sur- 

 face could not be reached. Only surface samples of the upper few milli- 

 meters were collected to approximate collecting a single sedimentation 

 unit. Only sand samples were taken; gravel was avoided on mixed beaches, 

 and if the beach was all gravel no sample was collected. Also, the sample 

 was collected from undisturbed positions on the profile traverse. Approxi- 

 mately 50 grams of sediment was collected, placed in a waterproof plastic 

 bag, and labeled. 



In the laboratory each sample was ovendried and split with an Otto 

 Microsplitter to a 12- to 15-gram sample. About one-half of this amount 

 was introduced into the Benthos Rapid Sediment Analyzer which plots a 

 cumulative distribution curve for the sample. Two samples were run ini- 

 tially; if they were similar, the first one was analyzed; however, if not, 

 a third sample was analyzed and mean values from all three were used. 



Mean grain size, sorting, and skewness were calculated by a graphic 

 method using 16th, 50th, and 84th percentiles. 



2. Textural Nature of Beach Sediments . 



A great deal of time and effort was devoted to collecting and analyzing 

 beach sediments to determine if there were spatial trends in sediment char- 

 acteristics (primarily size and composition) along the 17 sites, or if there 

 was a correlation between beach material characteristics and erosion. No 

 trends or correlation were found. 



59 



