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20. Abstract. (Continued) 



maximum bluff erosion at any one site between monthly surveys was 20 feet at 

 profile 4 in June 1972. Variables affecting the rate of movement of the 

 bluff include lake level, composition of the bluff or terrace, orientation 

 and straightness of shoreline, wave climate, manmade structures, and possibly 

 longshore bars. There was a lack of correlation between bluff erosion at 

 nearby stations, but each site varied seasonally with maximum erosion 

 occurring in late fall when storm occurrence is also high. Shore ice protected 

 the beaches in winter; erosion resumed in spring at a reduced level. Beach 

 width from the base of the bluff to the water level at the time of the survey 

 also varied seasonally, with beaches narrow in early summer when lake level is 

 at a maximum and wider in late fall when lake level is at a lower level. 

 The study beaches were mostly well-sorted sand (mean grain size between 0.330 

 to 0.189 millimeter or 1.60 and 2.40 phi units) with some gravel and heavy 

 mineral concentrations. 



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