In the first year the erosion took place later than normal, between 20 

 December and the time of ice formation in January. Usually the beach is 

 frozen by mid-December and further erosion is retarded or prevented 

 because of ice protection. 



Erosion during 1971-72 took place between late November and late 

 December which was characteristically the period of greatest storm 

 activity and erosion. This location appears to be an "average" site 

 since a small amount of erosion is normal during periods of combined high 

 water and storm activity. There is no evidence to suggest that any local 

 factors exert an influence over the processes operating at this site. 



4. Profile Site 4 . 



The most abrupt and extreme changes have taken place at this site 

 (Fig. 9). There was essentially no retreat of the dune bluff in the 

 first year; however, considerable beach erosion occurred in the spring 

 of 1971. Substantial erosion of the bluff (12 feet) occurred the 

 following fall. The erosion in the spring of 1972 was tremendous; 30 feet 

 of the bluff had eroded and 20 feet of the recession occurred during a 

 single sampling interval. Although there was slight erosion at a few 

 other locations during this period, the situation at this site was an 

 isolated one. 



Two factors may have contributed to the great amount of erosion. At 

 the apex of Big Sable Point there is a vertical, steel wall protecting a 

 U.S. Coast Guard installation and it is believed that the reflection and 

 refraction of waves concentrate wave energy just to the south of this 

 structure. The long fetch to the southwest also results in larger waves, 

 which tend to increase the erosion. 



The second important factor is that what was a wide protective beach 

 had severely eroded during the spring of 1971. With little summer 

 recovery, subsequent high energy periods during the following fall and 

 spring enabled waves to directly attack the dune bluff. 



5. Profile Site 5 . 



Nearly all of the terrace erosion at this site (Fig. 10} was during 

 a 2-month period in the fall of 1970. Similar erosion did not take place 

 at either of the adjacent sites during that period. Steep bluffs just to 

 the north of the site were severely eroded throughout most of the study 

 period. This site and site 10 with a similar shoreline orientation, were 

 the only sites subjected to significant erosion during October and 

 November 1970. This suggests a single storm was probably responsible 

 for the erosion and had little effect at the other sites because of their 

 different orientation to the wave approach. 



Significant beach accretion occurred at site 5 in the spring of 1972; 

 much sand was placed on what is normally a pebble and cobble beach. This 



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