GLACIAL WATERS IN CENTRAL NEW YORK 45 



Rush-Mendon. The delta near Fishers built by the Rush-Mendon 

 series of channels is well defined and not seriously eroded, though 

 not as large as might be expected from the size and length of the 

 stream channels. It seems probable that most of the detritus of the 

 higher channels was partially or largely dropped in the low places 

 along the stream courses, while that of the lower channels being 

 Salina shales has been reduced by grinding and the product carried 

 far away. 



Victor-Phelps. The ice-border rivers in the Victor- Manchester- 

 Clifton Springs-Phelps channels [pi. 3] had low gradient and small 

 carrying power. They were mostly on the limestones and secured 

 little detritus by their own corrasion. Probably a large portion of 

 their load was used to fill low places along the stream courses and 

 grade the channels ; an illustration is the sandy plain northwest of 

 Manchester. The final deposits of this 20 odd miles of stream flow 

 form the somewhat anomalous and extended delta between Phelps 

 and Geneva. This deposit of gravel and sand has a decided slope 

 to the east and grades east and south into silts, as if it were a veneer 

 on the valley slope. The direction of the channels and the trend of 

 the delta seems to indicate that the ice front occupied the ground 

 on the east. The sub-Warren waters at a later time held possession 

 of this district, and lake silts and dune sands are spread over the 

 surface toward Waterloo. The delta has been much gullied by 

 storm-wash and largely eroded, as shown by the map contours, to 

 a degree unusual for a sand-gravel deposit. 



Fairport-Lyons. The splendid channel between Fairport and 

 Lyons has no commensurate delta. For reasons already given it 

 seems probable that the depressions occupied by the later streams 

 were cut by the ice border drainage of an earlier ice invasion. The 

 channel is in drift and the soft Vernon shales of the Salina, and the 

 product of the stream corrasion in rock was not of delta-making 

 character. Moreover such detritus as the stream obtained was 

 spread over the low grounds in the swampy tracts to the eastward, 

 specially along the Clyde river, beyond Lyons and southeast of Clyde. 



Elbridge district. The deltas at Hartlot and Elbridge [pi. 4]. as 

 noted on page 26, seem to be chiefly the product of land drainage, 

 by the Skaneateles outlet. 



Marcellus valley. The excellent delta in the Marcellus valley at 

 the mouth of the Gulf channel is small in area relative to the great 

 rock channel. It is composed largely of coarse limestone derived 

 from the intake district, and has suffered little erosion by post- 



