238 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



The glacial waters usually found exit into valleys that were only 200 

 to 300 feet above the Allegheny, but a few points were found where the 

 discharge took place at much higher altitude. Thus at the head of Gordon 

 Hun, a tributary which enters the Allegheny at Tidioute, a line of glacial 

 discharge has formed a flat-bottomed channel at a height of 1,750 feet above 

 tide, or more than 600 feet above the river. There is a much lower tract to 

 the north which must have been covered by the ice sheet at the time waters 

 were discharged into Grordon Run. A neighboring valley. Perry Magee 

 Run, received glacial waters at about as high an altitude as Gordon Run. 

 The headwaters of Pithole Creek also received glacial waters while the ice 

 was occupying the lowland to the north. The altitude of this stream is but 

 little lower than of the tributaries just mentioned. 



There seems to have been but one eastern tributary of the Allegheny 

 which received a glacial outwash, Tionesta Valley. The outwash in this 

 valley will be considered first, after which that in the Lower Allegheny, the 

 Beaver, and the Upper Ohio will be taken up. Possible lines of discharge 

 in southwestern New York during this ice invasion are discussed to better 

 advantage in connection with the terraces of Wisconsin age. 



TIONESTA VALLEY. 



From Clarendon, near the bend of the Tionesta, a stream of consid- 

 erable volume and strength must have discharged from the ice sheet into 

 the lower Tionesta Valley. A channel one-fourth to one-half mile in width 

 passes from the present divide southward to the bend of the Tionesta, on 

 the borders of which the glacial deposits rise in places to a height of 100 ^ 

 feet above its swampy bottom. This channel stands about 1,400 feet above 

 tide, or 226 feet above the Allegheny River. It falls nearly 60 feet in 5 

 miles to Sheffield. Below this village, as noted in Chapter III, an old 

 divide is crossed by the Tionesta, and the valley for several miles is 

 very narrow and carries but little glacial outwash. The writer's obser- 

 vations were extended only 3 or 4 miles below Sheffield, but Wright 

 has followed the valley down to its mouth and reports the occun'ence of 

 glacial gravel in small amount at a few points in its lower course. N. P. 

 Wheeler, of Tidioute, reports that just back of Newtown Mills, a few miles 

 above the mouth of the Tionesta River, there is a terrace of glacial gravel 

 which stands about 100 feet above the stream, or 1,250 feet above tide. 

 Wheeler estimates the width of the terrace to be one-eighth of a mile or 



