LAKE CHICAGO AND ITS OLD SHORE LINES 



81 



spit at the mouth of this bay and the spits at the ends of Blue 

 Island. There was a great branching spit running south and 

 west from a point below the present Winnetka reaching Niles 

 Center, which spit then inclosed Skokie Bay and now forms the 

 irregular eastern border of Skokie Marsh. The waters of the 



FIG. 50. Lakes Chicago, Saginaw, and Maumee. Lake Maumee at an 

 earlier stage was more extensive and outletted down the Wabash Valley as indicated 

 by dotted lines. All three lakes now discharge through the Chicago outlet. This 

 represents about the Glenwood stage of Lake Chicago. Modified from Leverett 

 and Taylor. 



lake, moving toward the outlet or currents set up by the prevail- 

 ing north winds checked by these projecting points, dropped 

 their load of sediment in sand bars. The wash of the waves 

 piled the material up above the lake level in these spits, just as 

 they are formed along the lake shore today by the same agencies. 

 Lake Chicago continued to grow in size as the front of the 

 glacier retreated. But what is more important from our interest 



