None of the profile traces showed any flat areas or contained any other 

 indications of a till or boulder pavement between the bars. These condi- 

 tions were found in some of the profiles surveyed by previous investigators 

 (Davis, 1964; Saylor and Hands, 1970). Boulder pavements were present at 

 site 13 in August 1963 (Davis, 1964). 



Site 5, 6, and 7 of this study include the Little Sable Point area 

 where bars were studied more intensively by Hands (1976) . As shown in 

 Figures 18, 19, and 20 of Hands (1976), the bars change position or disap- 

 pear over short distances in this area, suggesting that the first, second, 

 or third bars from sites as widely spaced as in this study are not the same 

 bars from site to site. 



3. Effects of Longshore Bars on Beach Changes . 



This section examines each of the 17 sites for evidence to support the 

 author's hypothesis that the presence of longshore bars close to shore and 

 at shallow depths acts to protect the shore from erosion. Two assumptions 

 are made concerning the effects of longshore bars on changes that occur in 

 the profile of the beach and adjacent coast. The first assumption concerns 

 the permanence of the profiles. The bar profiles previously described 

 were surveyed at the beginning of the third year (August 1972) . In the fol- 

 lowing discussion it will be assumed that these nearshore profiles, with 

 the exception of the ephemeral bars, prevailed throughout the third year. 

 Based on data by Evans (1940) , Davis and McGeary (1965) , and Saylor and 

 Hands (1970), this appears to be a reasonable assumption. Presence and 

 location of ephemeral bars were noted when possible during the monthly 

 visits, and will be incorporated in the discussion. The second assump- 

 tion is that the bars protect the beach and backshore from erosion, 

 other factors being equal . 



a. Profile Site 1. This site experienced an increasing amount of vol- 

 ume loss on the profile during the study period. Although there were only 

 26 cubic feet removed during the first year, the final year had a loss of 

 222 cubic feet. An ephemeral bar was not observed during the entire study 

 period. The depths of the two bars are 1 foot or more greater than the 

 mean for all sites, and the distance of the first bar is slightly greater 

 than the mean (Table 6). In addition, the depth difference between bar 

 crests is 1 foot above the mean. These parameters and the relatively steep, 

 inner nearshore profile permit a relatively high amount of wave energy to 

 reach the beach. 



b. Profile Site 2 . Very little loss of sediment was recorded at this 

 site with the maximum being 42 cubic feet during the final year. Although 

 the mean depth of the "permanent" bars is in excess of the mean for all 

 sites, the distance of the bar crests from the shore is slightly below the 

 mean. More importantly, ephemeral bars are typical at this site and the 

 profile immediately adjacent to the strand line is gentle. It is assumed 

 that these bars reduce the wave energy reaching the beach, the ephemeral 

 bar serving as an effective protection for the coast. 



55 



