ESKERS IN THE VICINITY OF ROCHESTER, NEW YORK. 217 



Origin. There was little developed in the study of these Pal- 

 myra esker segments that throws light on the precise manner of 

 origin. If the broad elevation on which the northern and highest 

 part of Ridge B is located is to be interpreted as till and possibly as 

 a drumlin then the esker was deposited after the deposition of this 

 till. However, that does not necessarily mean that the esker stream 

 was superglacial even in this part of its course. 



The presence of several kettles depressed into the crest of the 

 eskers would indicate ice block inclusion with subsequent melting 

 leaving the depression, or possibly the places of rest of the sagging 

 ice arch over the broad subglacial tunnel, either interpretation favor- 

 ing the subglacial origin of the esker. 



Probably each ridge was built when the ice front stood near its 

 southern terminus. In each case this was followed by ice recession 

 and the building of the next ridge northward followed. The pres- 

 ence of kame areas near the ends of the individual ridges would 

 seem to indicate this, the kames representing the outwash beyond the 

 stagnant ice front from the stream in which the individual esker 

 ridges were being deposited. 



The trend of this esker system along the axis of a valley rein- 

 forces the idea of its origin in a subglacial stream. 



Eskers of the Mcndon kame area. Figures 10-11, plates XIIT. 

 XIV. The Mendon kame area lies about 12 miles south of Rochester. 

 It has been described by Prof. Fairchild (34), who mentions briefly 

 the eskers of the area. 



All of the eskers of this kame area are excellently developed, in 

 fact the one on the east side of the area east of Mendon pond is 

 probably the finest esker in Western New York. The Rochester 

 topographic quadrangle indicates the eskers of this region, although 

 very inadequately. They all trend north and south and pursue 

 meandering courses. They are of historic interest because their 

 crests were utilized as trails by the Indians in passing northward to 

 the vicinity of the present village of Pittsford. 



Esker zvesf of Mendon pond. Figure 10, plate XIII. West of 

 Mendon pond occurs an esker that is nearly two miles long and in 

 places attains a height of 100 feet. 



On the north it rises from a low swampy tract and passes west- 

 Avard for about 600 feet with a height of less than 5 feet. Turning 



