developed beach, erosion in June 1971 left the beach narrow throughout the 

 early summer. 



Some beach accretion occurred in September 1971, followed by general 

 erosion through the fall with both the beach and the terrace experiencing 

 retreat. Accretion during the spring of 1972 provided a fairly wide beach 

 but this was followed by erosion during June of that year. 



The summer of 1972 was a period of gradual accretion. It was followed 

 by a long-term period of erosion during the fall, with 16 feet of the ter- 

 race removed. More terrace erosion occurred after ice breakup in 1973. 

 The beach accreted in March 1973 but then eroded during June 1973. 



d. Profile Site 4 . This site is about 300 yards south of the light- 

 house and the recently abandoned U.S. Coast Guard station at Big Sable 

 Point. An arcuate steel seawall protects the installation; waves reflect- 

 ing from the seawall may exert some influence on the beach at the profile 

 site. The coastal area is composed of extensive dunes which are somewhat 

 active and contain blowouts. Grass and small bushes cover most of the 

 dunes which rise up to 30 feet above lake level. 



At the start of the surveying program there was a broad beach. Modest 

 erosion occurred in September 1970, but there was no noticeable change in 

 beach width until shortly after the breakup of shore ice in the spring of 

 1971. From April to June 1971, beach erosion was severe and the face of 

 the dune eroded 2 feet . 



Although there was no appreciable accretion during the following sum- 

 mer, the period of September to December was one of marked beach growth; 

 the dune face retreated 12 feet during this period. This further empha- 

 sized the rapid rate of beach recovery in that each of the surveys in 

 September, October, and November 1971 had shown a net beach growth from 

 the previous survey. This means that in each of the 4-week intervals there 

 were both beach and terrace erosion followed by rapid beach accretion which 

 resulted in net growth. Shortly after the breakup of shore ice, the beach 

 was almost totally removed. This situation, coupled with erosion to the 

 dune, characterized the spring of 1972. The largest, single-period slope 

 retreat for any location (20 feet) was recorded here on the June 1972 

 survey. 



Because of the severe erosion, virtually no beach existed through the 

 late summer of 1972. A modest increase in beach width, which was partly 

 attributed to the fall decrease in lake level, occurred in October and 

 November 1972. There was a marked net growth of the beach throughout the 

 spring and summer of 1973. 



e. Profile Site 5 . The coastal area at this site is dominated by 

 high bluffs which rise about 40 feet above the lake; however, this partic- 

 ular profile line crosses a sand terrace. There is abundant evidence of 

 an extremely thin sand and gravel prism over the Pleistocene glacial drift. 

 After periods of erosion the coarse cobble lag accumulations, which are 



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