200 LIFE OF THE PLEISTOCENE 



and many channels have been mapped, indicating the preglacial drainage 

 systems of the Ohio, Muskingum, Great and Little Miami, Mad, Wabash, 

 Vermilion, Black and Rocky rivers, besides numerous smaller streams. 9 These 

 buried valleys indicate changes of channel in many places, the change in some 

 instances being notably marked. Several streams with a present southward 

 drainage are shown to have drained northward in preglacial times. In southern 

 Indiana, the lower Wabash and its tributary rivers, as well as the Ohio River, 

 flowed in preglacial channels which are now drift-filled and the present streams 

 have excavated new channels for the most part. 10 The Ohio River did not 

 exist at that time as a separate stream. Its present channel was occupied by 

 a series of disconnected water courses, varying in size from small ravines to 

 large rivers. Many of the streams in West Virginia and Kentucky flowed 

 northward across Ohio, using the drainage channels now occupied by streams 

 flowing in the opposite direction. Presumably they entered river channels 

 now the site of the Great Lakes and the Wabash River. 11 



In western Illinois a river system composed partly of the present Pecatonica, 

 Rock, and Illinois rivers, has been more or less perfectly worked out by Leverett 

 and other geologists. 12 The drainage was southward and indicates that the 

 Mississippi above the Rock Island rapids turned southeast and joined the 

 southward trunk of the Rock River (in a preglacial channel) near the Town of 

 Ohio, the combined streams forming a large river (the preglacial Illinois) 

 which joined the modern Illinois below Hennepin. Well records made in 

 Iroquois, Champaign, Livingston, and McLean counties indicate that an old 

 valley extends southward from Lake Michigan thru portions of these counties. 

 At Chatsworth, Livingston County, its depth is 200 feet, and at Bloomington 

 the trough is 230 feet deep. Between Onarga and Gilman it is 268 feet and 

 near Spring Creek station it is over 400 feet beneath the surface. 13 Similar 

 buried channels are known in the region bordering the southern shore of Lake 

 Michigan. 14 



In Iowa a number of preglacial river channels have been traced, especially 

 in the southeastern portion of the state, where the Mississippi and tributary 

 streams have been shown to have occupied other and larger valleys in preglacial 



'Tight, Bownocker, Todd, Fowke, The Preglacial Drainage of Ohio, Special Papers, 

 No. 3, Ohio Acad. Sci., 1900. 



10 Leverett, Illinois Glacial Lobe, plates 8 and 9; pp. 93, 96, 102, etc. 



11 Tight, Professional Papers, U. S. G. S., No. 13. The map, plate 1, indicates the pregla- 

 cial drainages of these rivers, which are given names. Two of the rivers seem to have been 

 christened ahead}'. Thus Tight's Pittsburg River seems to be the same as the Spencer River 

 of Forshay, and the Cuyahoga is the same as the preglacial Newberry River. 



12 111. Glacial Lobe, plate 12. 



13 See Geology of Ohio, II, pp. 13-14; Bradley; Geol. 111., IV, pp. 229-230, 1870. 

 " See Chapter III. 



