532 THE ILLINOIS GLACIAL LOBE. 



PATOKA RIVER. 



This eastern tributary of the Wabash has a drainage area of nearly 

 1,000 square miles. Its watershed is long and narrow, being about 80 miles 

 in length and less than 15 miles in average width, and lies between the 

 watershed of East White River and the watersheds of several small streams 

 which are directly tributary to the Ohio. The interesting drainage modi- 

 fications which resulted in the production of the present Patoka River have 

 already been considered (pp. 98-102). 



WHITE RIVER. 



The entire watershed of White River is about 11,000 square miles. 

 Exclusive of East Fork it embraces about 6,000 square miles. The East 

 Fork enters the district covered by the Illinois lobe only in the portion 

 below the bend west of Shoals, and therefore lies mainly outside the field 

 of the present discussion, which is restricted to the lower course of the 

 main White River. 



Near Martinsville, in southern Morgan County, White River leaves 

 the district which has been covered by more eastern portions of the ice 

 sheet, and from this point to its mouth, a distance of 125 miles by direct 

 line, lies within the limits of the district covered by the Illinois lobe. That 

 lobe encroached only a few miles upon territory east of White River, the 

 greatest known extension being about 20 miles, at points where it touches 

 upon East White Valley east and south of Loogootee in western Martin 

 County. Throughout much of the distance below Martinsville the glacial 

 boundary is within 10 miles east of the east bluff of the present river. 



The valley of White River for a few miles below Martinsville, although 

 including sections of a preglacial line or lines, has not been definitely con- 

 nected with the preglacial line occupied by the stream in its lower course. 

 The river crosses a rock ridge just below Ramona, another just above 

 Spencer, while below Spencer it flows for a few miles in a narrow shallow 

 channel among hills and ridges, there being apparently no definite pre- 

 glacial drainage line to control its course. It occupies a preglacial valley 

 from the mouth of Raccoon Creek down to Worthington, having a width of 

 nearly a mile. Near Worthington the valley joins a larger preglacial val- 

 ley, 2 to 2£ miles wide, which leads in from the north along the lower 



