388 THE ILLINOIS GLACIAL LOBE. 



border of the ridge under discussion a valley-like depression which forms 

 a natural line for drainage between the gaps through which the streams pass 



The width of this ridge averages scarcely 1 mile and in places is but 

 one-half mile. It has usually an abrupt outer border and a more gradual 

 slope on the inner border. This feature is maintained where the ridge has 

 a double crest, as well as where it is single. 



Although the ridge usually presents a well-defined crest, it is seldom 

 sharply morainic. Indeed, the surface is nearly as smooth as on portions 

 of the bordering plains. The highest knolls scarcely exceed 15 feet, and 

 the majority are but 5 to 10 feet in height. For a few miles near the State 

 line the crest is sharp. It is also sharp in Porter County, Indiana, west 

 from Furness. Usually it is nearly as smooth as the slopes. 



COVERT RIDGE. 



Covert Ridge receives its name from the village of Covert, in western 

 Van Buren County, Michigan, which stands on its crest. It lies between 

 the ridge just discussed and the shore of Lake Michigan, and is usually but 

 1 to 4 miles back from the shore of the lake. In places it comes to the lake 

 and has been partially eroded by the lake waves, as indicated below. 



Covert Ridge connects at the north with the Valparaiso morainic sys- 

 tem, its point of connection being in Overisel Township, in northern Allegan 

 County. It has, however, been traced a few miles farther north, along the 

 inner border of the Valparaiso system, in Zeeland and Jamestown town- 

 ships, Ottawa County, where its topography and structure distinguish it 

 from the bordering Valparaiso moraine. No attempt has been made to 

 trace it farther north. From Overisel Township it leads southwestward 

 through the village of East Sazigatuck to the Kalamazoo River, at New 

 Richmond. The river makes only a narrow break scarcely more than a 

 half mile in width, and the ridge continues southwestward coming to the 

 shore of Lake Michigan, near the line of Granges and Casco townships, 

 Allegan County, exactly opposite the State line of Wisconsin and Illinois. 

 In the middle part of the west boundary of Casco Township the lake has 

 cut away nearly all of the ridge, leaving only a strip about one-fourth mile 

 wide, belonging to its east slope. From this point the ridge bears nearly 

 due south while the lake border bears west of south, and at South Haven 

 its inner border is nearly a mile east of the lake. It continues south nearly 



