THE ANCIENT OUTLET OF LAKE MICHIGAN. 227 



tinctly defined than before, chiefly because of the smaller depth 

 to which it could be cut in the lower ground. The blufi's are only 

 about fifty feet high at Joliet, while at Morris, eight miles below 

 the entrance of the Kankakee, they are hardly perceptible. 

 Through this district the floor of the old channel is generally 

 rocky, and in the floor the Desplaines River or the Illinois, as it 

 is called below the entrance of the Kankakee has cut a narrow 

 and shallow trench. Occasionally heavy gravel beds were seen, 

 but their origin could not be determined in our rapid excursion. 



A peculiar feature of the northeastern part of this district is 

 the subdivision of the old channel into several courses, as if a 

 number of almost equally good lines of escape had been originally 

 ofl'ered to the lake overflow, along all of which the waters ran for 

 a time, but into one of which they were gradually collected, that 

 one being the channel now followed by the Desplaines past Joliet. 

 Two of these temporary branching channels are represented on 

 the Joliet sheet, a short distance above that city, in the form of 

 swampy passages connecting the Desplaines with the Dupage 

 River. A third is seen southwest of Joliet, and is now utilized by 

 the Illinois and Michigan Canal. 



The second belt of higher ground again reaches a level of 

 seven hundred and fifty feet north and south of the town of Mar- 

 seilles, after which it may be named ; and through this belt the 

 old channel again appears as a depressed linear plain, now about 

 a mile and a half wide at an altitude near four hundred and ninety 

 feet. It is inclosed by steep bluff's, a hundred or more feet in 

 height. Back from the bluffs, narrow and steep-sided ravines dis- 

 sect the rolling upland for a distance of from two to four miles. 

 There are flat alluvial fans in front of some of these ravines, and 

 it may be for this reason that several small lateral streams in 

 the neighborhood of Marseilles enter the river by direct courses 

 instead of first running a distance down the valley, as is so often 

 the habit of side streams while traversing the flood plain of their 

 master. The contour lines of the maps do not indicate the occur- 

 rence of any fans, the lines being concave toward the mouth of 

 the streams ; but I think some of them should be slightly convex 

 in that direction. It is possible that small matters of this kind 

 may have escaped the attention of the topographers, although the 

 scale of the maps is large enough to show them clearly if they 

 really exist. As in the Morris basin, the present river about Mar- 

 seilles is sunk in a narrow trench, twenty or thirty feet below the 

 broad plain of the old channel bottom. 



West of the Marseilles morainic belt the second belt of higher 

 ground there is a broad stretch of even country at a height of 

 about six hundred and fifty feet. The city of Ottawa is located 

 in the old channel where it traverses this even upland ; the in- 



