358 THE ILLINOIS GLACIAL LOBE. 



end of the sandstone belt above noted. This is about 5 feet square and 18 

 to 20 inches in thickness. Probably other large bowlders occur in this 

 region, for no exhaustive search was made. The sandstone bowlders appear 

 to be of northern derivation, though the exact locality and geological horizon 

 of the beds from which they came have not been determined. One of the 

 limestone bowlders in Van Buren County, examined by Dr. Alexander 

 Winchell, is referred by him to the Corniferous. Possibly the outcrop of 

 this rock is to the north beneath Lake Michigan. They are now at an 

 elevation of 150 feet above the level of the lake in a district where the 

 drift deposits are shown by the wells to be very thick. 



In this connection it may be remarked that one of these limestone 

 bowlders in Van Buren County has been referred to by Winchell in evi- 

 dence of a northward transportation of drift. 1 This bowlder is mentioned 

 in connection with others noted in Hillsdale, Jackson, and Lenawee coun- 

 ties, Michigan, and all are supposed to have been transported northwestward 

 bv an ice movement from the border of Lake Erie. Winchell was probably 

 correct in his interpretation of northward transportation into the counties in 

 southeastern Michigan, for the Lake Erie glacier would very naturally have 

 given limestones on the north border of the lake a northward transporta- 

 tion, but the Erie ice movement can scarcely be supposed to have extended 

 to Van Buren County. 



It may naturally be inferred that strong wells are difficult to obtain in 

 the portion of this morainic belt where till greatly predominates over sand 

 and gravel. It is found, however, that, with the exception of a small section 

 embracing southern Lake, northwestern Cook, and northern and eastern 

 Dupage counties, wells suitable for supplying stock and dairy farms may 

 be obtained at convenient depths. In Will County wells seldom reach a 

 depth of 100 feet because of abundance of water-bearing sand and gravel 

 at less depth. The same is true of Lake and Porter counties, Indiana, and 

 of much of Cook and Lake counties, Illinois. In the district where wells 

 are difficult to obtain, it is often necessary to sink to a depth of 150 feet or 

 more. This carries the wells into the older drift sheets beneath the Wis- 

 consin drift. Well sections obtained in the Illinois portion of this morainic 

 system are presented in the discussion of wells below; those in the Indiana 



'Am. Jour. Sci., 2d ser., Vol. XL, 1865, p. 331. 



