THE BLOOMINGTON MORAINIC SYSTEM. 257 



as in the south part of T. 23, Rs. 13 and 14 W., where it rises abruptly 30 

 feet or more above" the bordering portion of the moraine in a narrow belt a 

 half mile or less in width. South from the crest just mentioned there is, in 

 Vermilion and Warren counties, another ridge interrupted by occasional 

 gaps. The ridge is continuous from the north fork of Vermilion River near 

 Rossville eastward to its junction with the outer morainic belt at Pine 

 Creek in northern Warren and southern Benton counties. West from Ross- 

 ville it can be traced in a curving course southwestward to the Middle 

 Vermilion, near Potomac, and thence northwestward up the north side of 

 that stream. It is interrupted by a gap a mile or more in width immedi- 

 ately north of Potomac, and is deeply indented by valley-like sloughs at 

 points farther east. In the vicinity of Blue Grass, in western Vermilion 

 County, there is a plain occupying several squai-e miles which separates 

 this ridge from the one north of it, There is also a plain between the two 

 ridges from the bend of Vermilion River south of Hoopstown eastward into 

 Indiana as far as the ridges are traceable. The plain is scarcely 2 miles in 

 width in the Illinois portion, but reaches a width of 3 or 4 miles in Indiana. 

 The south ridge of this inner belt has usually a relief of about 50 feet 

 above the plain on the south, and slightly less above the plane tracts 

 lying between it and the north ridge. It is 2 or 3 miles in width, and 

 its crest lies nearer the south than the north border. Its topography is 

 similar to that of the north ridge, there being a gently undulating surface 

 with few knolls more than 20 feet in height. 



The portion covered by late Wisconsin drift. This mOl'aillic System is COUSpicUOUS fol' 



15 or 20 miles within the limits of the late Wisconsin drift, and, as noted 

 above, probably embraces the belt of thick drift which leads eastward 

 through central Indiana into Ohio. The north ridge maintains its usual 

 strength to the vicinity of Fowler, Indiana, where it terminates abruptly 

 in a marshy tract. The remainder of the belt swings around the eastern 

 end of the north ridge and dies out in a gently undulating tract 2 or 3 miles 

 east of Fowler. 



It is a question whether the ridges in Benton County have suffered 



much reduction by the late Wisconsin ice invasion. That invasion formed 



only weak moraines in this district, consisting usually of belts of low knolls 



only 5 or 10 feet in height, which are accompanied by a great number of 



mon xxxvni 17 



