194 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



Blue River has a fall of about 4J feet per mile, nearly as great as the 

 fall of the headwater poi'tion above Shelbyville. From Columbus to the 

 mouth of the Muscata,tuck, a distance of 55 miles, the average fall is very 

 nearly 20 inches per mile. In the remaining 125 miles, where the stream 

 is flowing in a preglacial valley, the fall is about 10 inches per mile. 

 In this portion there are, however, occasional riffles and rapids in which 

 a descent of several feet is made within a mile. The most conspicuous of 

 these rapids is at Hindostan, where a fall of about 5 feet occurs. At this 

 point the stream has cut off an old oxbow and is excavating the rock in the 

 ridge encircled by the oxbow. 



The Muscatatuck River in its lower 25 miles has very little fall com- 

 pared with the neighboring portion of East White River. At the railway 

 crossing south of Seymour the bed of the Muscatatuck is 40 feet lower 

 than at the crossing on the East White immediately north of Seymour. 

 The difference in g-radient is due to a filling- of the East White Valley by 

 deposits of gravel at the Wisconsin ice invasion. As the Muscatatuck 

 drainage system lies outside the limits of this later ice invasion or the reach 

 of its waters, its valley remains unfilled. The fall on the lower 25 miles 

 of the Miiscatatuck is apparently not more than 10 feet, while on East 

 White River, in the 25 miles above the mouth of the Muscatatuck, there 

 is a fall of about 50 feet. 



The portion of the East White River Valley lying within the ungla- 

 ciated districts of southern Indiana is cut to a comparatively low gradient, 

 notwithstanding the hardness of the rock formations through which its 

 course is channeled. The valley at present is silted up to a height of per- 

 haps 100 feet above the rock floor. The bluffs rise 200 to 300 feet or 

 more above the present valley bottom, thus giving the preglacial valley a 

 depth of 300 to 400 feet. If we consider this great depth and the hardness 

 of the formation, the width of the valley, which is seldom less than one- 

 third mile and probably averages more than one-half mile, is not surpris- 

 ingly small. The valley of this stream, like that of the Ohio in the 

 corresponding section, presents a series of oxbow curves, with very little 

 straight channeling. 



Within this unglaciated portion the East White receives one important 

 northern tributary. Salt Creek. This stream has a length of about 60 miles 

 from its headwaters, in Brown County, to its mouth, near Bedford, in Law- 



