in late February or early March but melts quickly; by early April most 

 of the ice is gone. About 10 percent of the lake surface is ice-covered 

 during a mild winter, 40 percent during a normal winter, and 80 'percent 

 during a severe winter (Rondy, 1969). Current patterns in southern 

 Lake Michigan distribute ice floes along the shore; even during a mild 

 winter shoreline ice may extend 10 to 15 miles offshore. Onshore winds 

 sometimes drive the ice onto the shore causing beach and property damage. 



111. COASTAL AND BEACH MORPHOLOGY 



1. Geomorphology of Eastern Lake Michigan . 



The Lake Michigan basin was formed by glacial erosion of bedrock and 

 preglacial stream erosion. The eastern shoreline of Lake Michigan is 

 underlain by Pleistocene glacial drift and characterized by reworked 

 glacial sediment; there is no rock exposure in the area. Shoreline 

 orientation changes from east-west in the south end to a general north- 

 south direction throughout most of the area. Little Sable Point, Big 

 Sable Point, and Point Betsie (Fig. 1) protrude westward interrupting the 

 general shoreline trend. Elevations along the shore range from 580 feet 

 to about 850 feet above sea level (Hulsey, 1962) , or from to about 270 

 feet above lake level. 



Profile sites are located adjacent to till bluffs, lake sands, active 

 dunes, and densely vegetated dunes. At the onset of the study, terraces 

 of lake sands, referred to as foredune terraces, extended seaward from 

 the dune or bluff at nearly every location except where active dunes 

 were present or till bluffs reached the beach. These terraces, recent 

 deposits containing beer cans and other recognizable human artifacts, 

 had accumulated during recent periods of low lake level. In the 2-year 

 study period many of these foredune terraces eroded and waves had access 

 to the dune or bluff. 



The volume of sediment along eastern Lake Michigan appears to be 

 generally small. At a few locations glacial till crops out in the 

 breaker zone after severe storm erosion. The direction of net longshore 

 transport (Fig. 5) is based on conclusions from a beach sediment study 

 by Hulsey (1962) , which considered such indicators as occurrences of 

 mineral types, geographic distribution of mean grain size, accumulations 

 of sand at littoral barriers, and wind and wave climate. The indicated 

 net transport south of Holland is southward, north of Holland northward, 

 and mixed between Little and Big Sable Points (Fig. 5). 



2. Beach Morphology . 



Geometry of Lake Michigan beaches is similar to tidal areas; beach 

 profiles show a rather horizontal backshore area and a nearly planar, 

 lakeward-sloping foreshore zone or beachface. During severe erosion the 

 beach profile may be a continuous, slightly concave upward foreshore 

 surface. A plunge step (small scarp) is commonly developed and marks the 

 lakeward margin of the beach except during high energy conditions. After 



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