196 THE ILLINOIS GLACIAL LOBE. 



At very few points between Shelbyville and Peoria are there knolls or 

 ridges worthy of note, almost the entire surface, both along' the crest and 

 the outer face of the moraine as well as its inner slope, being nearly plane. 

 Tlie outer face occupies a width of a mile or more. It shows slight 

 "irregularities of outline in the form of projecting points and bay-like reces- 

 sions, which cause a deviation of a half mile to a mile or more from a direct line. 

 North from the Sangamon River the surface is somewhat more undulatory 

 than in the interval between the Kaskaskia and Sangamon rivers, but the 

 drift swells are usually but 10 to 20 feet in height. The sharpest drift knoll 

 noted is about 2 miles north of Decatur and is scarcely 50 feet in height. 

 Knolls and ridges west of Forsythe are 30 feet or more in height. In south- 

 western McLean and southeastern Tazewell counties there are several 

 sharply outlined small ridges lying back 5 or G miles from the outer border 

 of the drift sheet and trending parallel with it. They rise 20 or 30 feet, 

 and in places 50 feet or more, above the bordering plains. In the portion 

 of the plain between the Mackinaw and Illinois rivers there is, in addition 

 to the relief of 50 or 60 feet on the inner border, an undulatory surface 

 with swells 10 to 25 feet in height. The portion north from Peoria has 

 only gentle swells 10 to 15 feet in height, but with these swells there are 

 occasional basins 3 to 6 feet in depth, which add somewhat to the expression 

 of the moraine. The moraine here is narrowed to a belt only 2 miles or so 

 in width, and, as the relief is 50 or 60 feet, the expression is more pro- 

 nounced than throughout the greater part of the border of this drift sheet. 



Eastward from Shelbyville the moraine is found to have very little 

 expression in eastern Shelby County, the surface being nearly as smooth 

 as that of the plain on the north. Upon approaching the Embarras Valley 

 in Coles County, the moraine is found to be separable into at least three 

 distinct ridges with east-west trend. The ridges each have a nearly plane 

 surface, with smooth slopes, but present a relief of 30 to 50 feet above the 

 intervening- sags. On the east side of the Embarras River, near the line of 

 Coles and Cumberland counties, a few knolls, 10 to 25 feet in height, 

 appear on the outer face of the outer ridge. In Edgar County the moraine 

 consist of two more or less distinct ridg'es. They are more distinct in the 

 southwestern than in the southeastern part of the county. In the vicinity 

 of Grand View and westward into Coles County the ridges stand about 

 50 feet above the sag which separates them. The south ridge is forest 



