528 



SCIENCE 



[N. S. Vol. XXVIII. No. 720 



tinued soutliward in a single valley about a 

 mile wide (Upper Genesee Valley), which is 

 only slightly clogged by drift. 



Beyond the Lower Falls, the ancient valley 

 is obscured by drift, yet not to the extent of 

 becoming untraceable. The modern river 

 makes a detour through the High Banks gorge, 

 the walls of which are over 500 feet high. At 

 St. Helena, four miles to the north of Portage- 

 ville, the modern river again enters the old 

 valley and continues in it for about 10 miles, 

 flowing northeasterly. This St. Helena val- 

 ley is clearly the northward continuation of 

 the Lower Falls Valley, the old connection 

 being drift fiUed. This course of the ancient 

 valley (now partly reoccupied by the Genesee), 

 from St. Helena to the Lower Falls, and 

 thence in a direct line to Portageville, was 

 outlined by Hall in 1842. Several miles above 

 Mount Morris the modern river leaves this 

 ancient St. Helena Valley, and has cut a 

 fourth short gorge. At Mount Morris the 

 modern river enters at right angles, from the 

 west, a broad open valley nearly three miles 

 in width and with a rock bottom 190 feet 

 below the river level, and therefore more than 

 600 feet below the rock bottom of the ancient 

 valleys first described, and more than 650 

 feet below the rock bottom (as tested by bor- 

 ings) of the Upper Genesee Valley at Por- 

 tageville less than twenty miles away. In 

 this broad and deep ancient valley, to which 

 the present author fifteen years ago applied 

 the name Preglacial Canaseraga Valley, the 

 Genesee continues for thirty-five miles to 

 Rochester, where it enters the Rochester gorge 

 with its three falls. The preglacial Cana- 

 seraga Valley, which contains the Genesee 

 flats north of Mount Morris, is continued 

 southward as an open valley for flfteen miles 

 to Dansville, beyond which it is choked by 

 drift. The modern Canaseraga follows this 

 valley to its junction with the Genesee at 

 Mount Morris. This valley is clearly an inde- 

 pendent valley, parallel to the Upper Genesee 

 Valley, and cut by an independent stream 

 as suggested by the author in 1894. 

 There is practical unanimity of opinion on 

 this point. The question at issue is : was this 

 a northward or a southward flowing stream? 



It is generally held that this was a northward 

 flowing stream, and that the Genesee, also a 

 northward-flowing stream in preglacial times, 

 joined the stream of this valley south of 

 Mount Morris, by way of the broad Nunda 

 Valley. The present Nunda Eiver enters the 

 Canaseraga Valley through a rock gorge. A 

 careful examination of the banks of the 

 Canaseraga Valley from Mount Morris south- 

 ward, shows rock exposures everywhere, the 

 lowest of which are more than 200 feet above 

 the present bottom of the Canaseraga Valley. 

 The Genesee could not enter this valley except 

 hy a narrow gorge. Moreover, unless it is as- 

 sumed that the Canaseraga Valley was 

 deepened by glacial erosion to the extent of 

 600 feet below its original depth, the Genesee 

 could not be its tributary, since the old rock 

 floor of the Genesee Valley is more than 600 

 feet above that of the Canaseraga Valley, the 

 distance between the two being not much over 

 fifteen miles along the supposed ancient 

 course. 



Attention is now invited to the Glen Iris 

 Valley. This is half a mile or more in width, 

 and 250 feet deep. Evidently such a valley 

 could only have been cut by a stream of some 

 length. If the Genesee flowed northward by 

 way of the Nunda or some other channel, this 

 valley must have been that of a tributary 

 stream, unless it marks the path of the north- 

 ward-flowing Genesee itself, as formerly sug- 

 gested by the author. In any case this valley 

 must have been continued far beyond Glen 

 Iris. It is filled by local drift. For ten miles 

 northwest from Glen Iris the country is flat 

 and deeply drift-covered. Then we come to 

 the Warsaw Valley, an ancient valley extend- 

 ing northwestward, and later bending to the 

 north. At the bend north of Warsaw, another 

 ancient valley, the Dale Valley joins it from 

 the northwest. The junction is somewhat ob- 

 scured by drift, but can be traced. The Dale 

 Valley at its junction with the Warsaw Valley 

 is as broad and deep as anywhere along its 

 course. It is evidently a tributary valley. If 

 the Warsaw Valley was cut by a northward- 

 flowing stream, two streams, one from the 

 southeast, and the other from the northwest 

 came together at Warsaw in exactly opposite 



