180 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



water passing through this valley was apparently very great, for it left a 

 silt deposit nearly 100 feet in depth. 



This stream has a valley 80 to 120 rods in width from a point near the 

 present divide at Camba northward to the junction with Buckeye Creek, 2 

 miles below Jackson. It there enters the Logan conglomerate and becomes 

 narrowed abruptly to a width of less than 200 yards. It continues narrow 

 nearly to its junction with Middle and North forks. This constriction does 

 not appear to mark an old divide, but on the contrary seems to be due 

 entirely to the great resistance of the conglomerate to erosion. 



LITTLE MIAMI RIVER. 



Little Miami River, which enters the Ohio just above Cincinnati, is the 

 first large northern tributary below the Scioto, yet the distance between 

 the mouths of the two streams is more than 100 miles. The source of the 

 stream is a few miles southeast of Springfield, Ohio, and the course is west 

 of south to the Ohio. The length of the stream is about 100 miles and 

 the drainage area probably 1,850 square miles. The East Fork, which is a 

 nearly independent drainage basin, rises in southeastern Clinton County, 

 a few miles east of Wilmington, and enters the main stream about 10 miles 

 above its mouth. Two other important eastern tributaries are Todds Fork, 

 entering at Morrow, and Csesars Creek, entering near Waynesville. There 

 are no large western tributaries. 



RATE OF FALL. 



The source of the main stream and also that of East Fork are at an 

 altitude of about 1 ,150 feet above tide, while the mouth is less than 450 feet. 

 The fall is therefore rapid, that of the main stream averaging about 7 feet 

 per mile, while that of the East Fork is fully twice as rapid. In the 35 

 miles from its source to a point opposite Xenia the fall of the main stream 

 is nearly 400 feet, but in the next 35 miles, to Morrow, it is about 130 feet, 

 or only one-third as rapid as the headwater portion. In the lower 30 miles 

 the fall is about 180 feet, it being more rapid than in the middle portion. 



CHANGES IN DRAINAGE. 



The headwater portions, both of the main stream and of its tributaries, 

 flow in shallow valleys 50 to 60 feet or less in depth, but from a few miles 

 below Xenia to the mouth the valley is 200 to 300 feet or more in depth. 



