214 THE ILLINOIS GLACIAL LOBE. 



Passing to the east side of the Illinois, we find the Shelbyville and 

 Bloomington moraines closely associated at the east bluff of the river, but 

 becoming separated within a few miles southeast to a distance of 10 or 12 

 miles. An interval of this width separates them from the Mackinaw River 

 southeastward to Kickapoo Creek, near the meridian of Bloomington. The 

 Shelbvville moraine there turns south and the Bloomington moraine turns 

 east, thus leaving a wider interval between the two morainic systems. In 

 the remaining 75 miles from the meridian of Bloomington eastward to the 

 Indiana line the interval between these morainic systems is 40 to 60 miles. 

 This interval, however, as stated above, is not entirely occupied by a plain, 

 but is crossed by several drift ridges, which form the Champaign morainic 

 system and the Cerro Grordo moraine, and these ridges are found mainly 

 east of the Sangamon River. A wide tract west of that stream has a 

 generally plane surface, with only occasional swells, and these but 10 to 30 

 feet or less in height. 



This tract included between the Shelbyville moraine on the west, the 

 Bloomington moraine on the north, and the Sangamon River Valley on the 

 east, is underlain by a very thick deposit of drift. Records of several wells 

 which penetrate more than 200 feet were obtained, and it is probable that 

 the average thickness of drift exceeds 200 feet throughout the entire tract. 

 The following represent the deepest wells of which records were obtained. 



At the village of Morton the waterworks well terminates in sand at a 

 depth of 230 feet, and three other wells within 2 miles northwest have about 

 the same depth, and none reach the rock. The engineer at the waterworks 

 states that for about 100 feet the drift is soft and easily penetrated, and is 

 mainly of blue color. This, presumably, is the depth of the Shelbyville 

 drift sheet. The next 100 feet is mostly a hard, gray till, though a bed of 

 sand 20 feet in depth is included. The lower 30 feet is white sand. 



At Hopedale, 12 miles south of Morton, near the inner border of the 

 Shelbyville moraine, a well made by the railway company reached a depth 

 of 195 feet. It was mainly till, except the lower 35 feet, which was a fine 

 sand. A bed of black muck was passed through between till sheets, but 

 the precise depth at which it occurred could not be ascertained. 



In southwestern McLean County a few wells have reached a depth of 

 200 feet without entering rock, lint the majority of tubular wells are 75 feet 

 or less in depth. The Shelbyville drift sheet apparently has at least this 



