ESKERS IN THE VICINITY OF ROCHESTER, NEW YORK. 213 



As already indicated the finest exposure is found at the southern 

 end of the esker. Here the whole ridge has been practically cut away 

 for more than 1,000 feet. At the east end of the excavation the 

 material is coarse at the top grading into fine gravel below. The 

 bedding is horizontal. Southwest 60 feet from here a layer of sand 

 6 feet thick occurs upon the remnant of the western flang of the 

 esker, which probably represents sand blown upon the esker subse- 

 quent to its formation. Four hundred feet farther southwest this 

 sand layer has disappeared entirely, the surface layers being coarse 

 gravel and rounded boulders, with finer gravel and some coarse sand 

 below, cross-bedding being very characteristic here. Southwest of 

 the north and south road the remnant of the esker remaining is com- 

 posed of coarse gravel chiefly. Sand occurs here again on the sur- 

 face of the slopes, and cross-bedding is excellently exhibited. A 

 study of the material throughout this whole excavation reveals the 

 fact that it is largely local in origin. 



It seems probable from recent study that the esker described 

 above represents only a portion of a very much longer esker system. 

 Chadwick in a recent paper, "Lake Deposits and Evolution of the 

 Lower Irondequoit Valley," describes a gravel ridge lying in the 

 Irondequoit valley that may well be a part of this esker. This ridge 

 divides the valley into two parts and extends southward to East 

 Rochester where extensive sand plains occur, probably representing 

 an esker fan. Three miles southeast of this fan lies the esker that 

 is described in this paper. Two or three miles beyond Bushnells 

 Basin southeast of Cartersville occurs another typical esker fan 

 which is probably associated with this esker system. The continua- 

 tion of the portion of the esker studied to this outwash plain has not 

 been traced as yet. It is further possible that this esker system may 

 continue north of Irondequoit Bay and lie concealed beneath the 

 waters of Lake Ontario. At any rate if all these features are to be 

 considered as a single esker system, which seems to be the correct 

 interpretation, then the Cartersville esker is the longest esker system 

 in Western New York. 



Origin. Some features exhibited by this esker throw light upon 

 its origin. The depression of the esker gravels below the general 

 surface on either hand, the preponderance of local material, and the 



