4. Summary . 



Almost no unexpected shoreline or bluff changes were observed on aerial 

 photos. General trends corresponded closely to lake level changes. Most 

 exceptions are explainable in light of geomorphic or geologic location on 

 the coast. Even the rates of change for most sites fall within a fairly 

 narrow range. Extreme rates of both erosion and accretion, e.g., site 6 

 (Fig. 9, left), are the result of the site location on Little Sable Point, 

 an area of much sediment accumulation. The rates presented are mean an- 

 nual rates for the time interval involved. To obtain improved information, 

 annual aerial photo coverage would be required. 



VII. NEARSHORE BOTTOM PROFILES 



One of the variables which may affect coastal processes and sedimenta- 

 tion is the presence of longshore bars which are ubiquitous throughout 

 eastern Lake Michigan (Hands, 1976). These sandbars are of considerable 

 importance in that they are a controlling factor in the amount of energy 

 imparted to the beach during storm conditions. This is due to the refrac- 

 tion and breaking of waves approaching and passing over the longshore bars. 

 As a result, the bar depth and distance from shore to bar are critical 

 factors. The number of bars and their configuration should be of some 

 importance also in controlling the wave and longshore current energy reach- 

 ing the beach. 



There have been a number of studies which have attempted to determine 

 both the details of the topography in the longshore bar and trough zone 

 and the stability of these bars. The first systematic study by Evans 

 (1940) indicated that the bars were fairly stable. This was supported by 

 findings of Davis and McGeary (1965) and Davis and Fox (1971) , who were par- 

 ticularly concerned with short-term changes in longshore bars as the result 

 of storms. They found no significant changes caused by storms in four dif- 

 ferent areas of the eastern Lake Michigan coast. However, it is the pre- 

 sent author's opinion that during storm conditions there are changes in the 

 bar and trough profile, but that as storm conditions subside there is a re- 

 turn to the equilibrium state that prevailed before the storm. As a result 

 no significant net changes can be seen after a storm. Data from Berrien 

 County, Michigan, tend to confirm the above hypothesis (Erwin Seibel, per- 

 sonal communication, 1972). 



Long-term changes in longshore bar position and bar sediment character- 

 istics were noted in a study by Saylor and Hands (1970) and Hands (1976) . 

 They found that as lake level increased in the late 1960 's there was a cor- 

 responding shoreward migration of the longshore bars. This is in contrast 

 with Evans' (194.0) opinion that the bars are left behind as relicts when 

 the lake level increases. 



1. Data Collection . 



Nearshore profiles were constructed at each of the 17 profile sites 

 from data collected during mid-August 1972, the beginning of the third 



