536 



JOHN L. RICH 



that below. The gorge bottom in this upper part is about 120 feet 

 wide and shows rock in only one or two places, then not sufficiently 

 to cause falls or rapids. The walls show marked decay. In line 

 with this upper gorge and running from the amphitheater to the side 

 of Cayuta Gorge is a sag of about fifteen feet in the surface which 

 undoubtedly marks the drift-filled continuation of the gorge above 

 (see Fig. 5). 



The Stream B, then, above the amphitheater, is flowing in a gorge 



distinctly broader 

 and older than the 

 interglacial one 

 which it follows 

 from the amphi- 

 theater to its junc- 

 tion with Cayuta 

 Gorge. If this 

 larger gorge is due 

 to a hanging condi- 

 tion initiated by the 

 cutting of Cayuta 

 Gorge then, in order 

 to explain the facts, 

 appeal must be 

 made to three pe- 

 riods of glaciation; 

 for what but the 

 intervention of a 

 glacier would ac- 

 count for the diver- 

 sion of the stream from its broader gorge to the one, itself interglacial, 

 which it occupies in the lower part of its course ? It has been sug- 

 gested however, that the older gorge may be the result of a regional 

 rejuvenation antedating the appearance of the first ice-sheet. Such 

 a rejuvenation, evidence of which has been found by Tarr in many 

 of the streams of this region, might account for the conditions here 

 found without appeal to more than two periods of glaciation. 



It seems probable, however, if Stream B cut a gorge due to regional 



Fig. 5. — Sketch of tributary Stream B. Note the 

 broad upper gorge, and the narrower one, itself inter- 

 glacial, through which the stream reaches Cayuta 

 Gorge. 



