152 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



The principal data concerning the several fluvial plains which form the 

 basis of the above discussion are grouped in the following table: 



Height above tide of fluvial plaim along the Beaver and Shenango rivers. 



Mouth of Beaver River 



Beaver Falls 



Mouth of Conoquenessing River 



Head of Beaver River 



Newcastle 



Harbor Bridge 



Sharon 



Clarksville 



Greenville - 



Jamestown 



Outlet of Pymatuning Swamp. . 

 Head of Pymatuning Swamp. . . 



Miles. 

 

 5 

 9 



14 

 3 

 4 



17 



20 

 5 



13 

 9 



Gradation Buried Present 



plain. channel. stream. 



Feet. 

 865 to i 

 855± 

 840 

 810± 



800 

 780 



Feet. 



605i 



615 d 



682 



620=t 



645 



664 

 716 

 734 

 764 

 780 

 800 

 840 

 860 

 940 

 965 

 1,000 

 1,025 



LITTLE BEAVER RIVER. 



The Little Beaver, a small north tributary, flows into the Ohio near the 

 Ohio-Pennsylvania line. Its drainage area lies mainly in Ohio, though the 

 North Fork has much of its watershed in Pennsylvania. The northern half 

 of the area drained by the Little Beaver has been glaciated, and its pre- 

 glacial features are greatly obscured by heavy deposits of diift. Its general 

 elevation is scarcely so great as the unglaciated southern half This and 

 other features suggest that much of this drainage basin once had a north- 

 ward discharge to the old Beaver system. The lower course of the present 

 stream is very narrow, and in preglacial times may have carried but a 

 small fraction of the present drainage. The probable course or courses of 

 northward drainage and the extent of change in drainage have not been 

 determined. White reports that the North Fork has a sluggish flow through 

 a region heavily covered with drift from its source nearly to its junction 

 with the main creek at Fredericktown, Ohio, but that below that junction 

 the stream falls at the rate of 25 feet per mile.^ 



^ Second Geol. Survey Pennsylvania, Rept. Q, 1878, p. 6. 



