226 THE ILLINOIS GLACIAL LOBE. 



"Wabash Railway survey, is 30 or 35 feet, while the inner-border relief is 

 about 50 feet. The relief of the Inner Ridge throughout its entire course 

 in Illinois and Indiana is but 15 to 20 feet, except where knolls rise above 

 the general level of the crest. In such cases a relief of 40 or 50 feet may 

 be found. The combined Middle and Outer ridge has a general relief in 

 eastern Illinois of about 40 feet above the outer-border plain and about the 

 same relief above the inner border. Where there is a double crest, the sag 

 between the crests is 15 to 25 feet in depth. 



In the Indiana portion the relief seldom reaches 40 feet, and the aver- 

 age is probably 30 feet above the plains on the outer and inner border. 



It appears from the data just given that the outer and inner border 

 reliefs in this morainic system are not markedly different. There is not 

 such a filling on the inner border and transition from the moraine into the 

 plain as in the Shelby ville or Cerro Gordo moraines. As seen in profile, the 

 ridges of the Champaign system rise with nearly as rapid slope on the inner 

 as on the outer border, a feature which distinguishes them from nearly all 

 of the moraines of the Wisconsin series, it being the habit of the Wisconsin 

 moraines to present a long inner slope and a somewhat abrupt outer slope. 



RANGE IN ALTITUDE. 



As indicated above, the moraine, near the western end, attains an alti- 

 tude of 820 feet above tide, while the border plains are about 750 feet. The 

 altitude of the plains decreases to about 700 feet in southern Champaign 

 County and to 660 feet in the vicinity of the Embarras River, in northern 

 Douglas County. From this point eastward to the borders of the Wabash 

 the plains stand 650 to 675 feet along the border of the combined Middle 

 and Outer ridge. The altitude is less uniform along the line of the Inner 

 Ridge, there being a range of about 75 feet in the Illinois portion. The 

 highest part of the plain near Sandusky is fully 720 feet above tide, while 

 in the western part of the county it scarcely readies 675 feet, and in the 

 eastern it falls to about 650 feet. On the borders of the Wabash in western 

 Indiana the altitude of the upland plain declines to about 600 feet. There 

 is a gradual rise from the valley eastward to 775 or 800 feet in western 

 Montgomery County, where the moraines of this system pass beneath a 

 moraine of the late Wisconsin series. 





