710 THE ILLINOIS GLACIAL LOBE. 



In the vicinity of Greenview the drift is less than 100 feet in thickness. 

 The loess has a depth of 12 to 16 feet, and is separated from the underlying 

 till by a definite soil horizon. 



The record of a boring at Sweetwater, published in the Geology of 

 Illinois, is as follows: 



Section of a boring at Sweetwater, Illinois. 



Feet. 



Brown clay 



Sand I 1 



Blue clay ° 9 



Total drift n0 



Black soil at bottom of drift. 



Another deep boring, reported in the Geology of Illinois, is in a valley 

 in sec. 2, T. 17, R. 6 W., which reached a depth of 86 feet without entering 

 rock. Wood was found at 65 feet. 



Outcrops of rock occur in the west part of T. 18, R. 5 W., along ravines 

 at a level only 35 feet below the neighboring uplands, and wells east from 

 there near the county line enter rock at about 70 feet. 



CASS COUNTY. 

 GENERAL STATEMENT. 



Cass County is sittfated on the east side of the Illinois River, immedi- 

 ately south of the mouth of the Sangamon River, with Virginia as the 

 county seat, and has an area of 360 square miles. It is drained by small 

 streams tributary to the Sangamon and Illinois, and its drainage is much like 

 that of Menard County, rainfall being disposed of by the loess as well as 

 by a well-developed drainage system. There are extensive bottom lands 

 along the Sangamon and Illinois rivers, occupying about one-third the area 

 of the county. These bottoms have a sandy deposit, though usually their 

 soil is productive. 



Wells at Beardstown indicate that the Illinois Valley has a filling of at 

 least 100 feet, mainly sand and gravel. On the uplands the drift thickness 

 is known to the writer at only two points — Ashland and Virginia — being 

 85 feet at the former and 187 at the latter village. 



Wells are usually obtained at 25 to 50 feet, both on the bottom lands 

 and on the upland. The shallower ones obtain their supply above the blue 

 till, but the deeper ones on the uplands enter that deposit a few feet. 



