trough features in the nearshore zone in response to fluctuations of water levels 

 distributes the exposure and downcutting of the glacial till across the entire 

 profile. 



In a technical paper prepared for the U.S. Army Corps of Engineers, Hands 

 (1979) compared profiles compared for a 55-km stretch of shoreline on eastern 

 Lake Michigan. From 1967 to 1976, the profiles clearly showed the shoreward 

 migration of bar formations with rising lake levels (see Figure 29). Therefore, 

 changes in the position of bars, and the troughs between the bars where the till 

 is often exposed, result from changes in water levels. The range of water level 

 variation on Lake Michigan, explains how the downcutting can be distributed 

 across the entire shoreface. 



Bathymetry Comparisons and Sediment Budget 

 Calculations 



The authors recognize that comparisons of bathymetry that was mapped for 

 navigation purposes can sometimes produce misleading results due to the rela- 

 tive inaccuracy of these surveys. However, the extent of lake bed change at 



163 

 182 



isr 



180 

 179 

 178 

 177 

 176 

 175 

 174 



173 



STATION 10 



1 1 Sept. 1976 



1 3 Aug. 1975 



7Moy 1971 



= 22 July 1969 



100 



90 80 70 60 50 40 30 20 10 

 OittonM from BoM ( ffl ) 



-10 -20 -30 



-50 



Figure 29. Nearshore bar migration, eastern Lake Michigan (Hands 1979) 

 68 



Chapter 4 Analyses of Coastal Processes and Geomorphology 



