226 ROCHESTER ACADEMY OF SCIENCE. 



face seems to indicate that the stratified materials continue below the 

 general till surface. This excavation is now occupied in its deeper 

 part by a pond. The excavation west of the road exhibits fine gravel 

 only. 



The slopes of the esker are gentle and the gravelly surface has 

 developed sufficient soil to support vegetation. Its base rarely 

 reaches a width of 50 feet. 



About one-half mile west of the termination of the esker and 

 just north of the railroad a ridge starts abruptly from the level sur- 

 face and rapidly gains in height until an altitude of 50 feet is attained. 

 This ridge continues northwestward for more than 1,000 feet and 

 then turns northward and ceases rather abruptly. Its surface is of 

 gravel with an excavation near its summit in fine gravel, these fea- 

 tures together with its steep sides and change in direction give this 

 ridge a decidedly esker appearance. 



Northeastward this ridge is succeeded within a few hundred 

 feet by another ridge that abruptly rises to a height equal to that of 

 the first and as abruptly declines nearly to the level of the adjacent 

 topography where it is succeeded by a low broad ridge. This last 

 ridge is nowhere more than 20 or 30 feet above the adjacent surface, 

 and continues for a half mile or more toward the northeast. Possi- 

 bly these developments may be interpreted as the main esker, the one 

 mapped and described above being considered a small tributary to it. 

 This may help to explain the unusual direction of the latter. Further 

 study will be necessary to bring out the relationships and to deter- 

 mine if the high disconnected ridges are really a part of an esker sys- 

 tem. The topographic map very imperfectly exhibits these features. 



Origin. The manner of origin of the ridge shown on the 

 accompanying map (Fig. 12) is not demonstrated by the field study. 

 The fact that the gravels continue below the general surrounding 

 surface where one of the excavations occurs (see above) would 

 seem to indicate that the esker materials were deposited not later 

 than the deposition of the till which would favor the subglacial 

 method of origin. 



Eagle Harbor esker. Figures 13-14, plates XV, XVI. Three 

 miles south of Eagle Harbor, a small station on the Falls branch of 

 the New York Central railroad, occurs an esker several miles in 



