ESKERS IN THE VICINITY OF ROCHESTER, NEW YORK. 163 



revisited, and several additional occurrences not originally examined 

 were studied. The results are incorporated in the following paper.* 

 It is hoped that it will make some contribution to the subject of 

 eskers and to the general subject of glacial geology. The bibliogra- 

 phy at the end of the paper the writer has tried to make as complete 

 as possible. 



Eskers represent an interesting type of glacial phenomena. 

 Their peculiar form and trend excite interest even in the casual and 

 superficial observer, and a great deal has been written regarding 

 them. 



Definition. Eskers may be defined as long, winding ridges of 

 gravel and sand, commonly stratified, with steep slopes and narrow 

 crests, trending in the general direction of former ice movement. 

 They may strikingly resemble artificial railway embankments. 



Popular names of eskers. People familiar with these inter- 

 esting ridges have accorded them a great variety of names, some of 

 them indicative of their supposed origin, such as, horsebacks, hog- 

 backs, serpent kames. serpentine kames. whalebacks, ridges, wind- 

 rows, turnpikes, back furrows, ridge furrows, morriners, Indian 

 roads (99). 



Technical nojnenclatiire. Esker is the technical name now long 

 used in this country for this class of glacial phenomena. The term 

 is of Irish origin (44). The Swedish word "os", plural "osar", 

 sometimes written "as (asar)", has priority, but has never come into 

 use in America. In Scotland the term "kame" has been used to 

 designate these ridges, the word being probably derived from the 

 Teutonic "kam", meaning ridge (44) By general agreement the 

 term "kam", is now restricted to mounds and short ridges, fea- 

 tures developed perpendicular to the direction of ice movement, while 

 the word "esker" is applied to ridges extending in the general direc- 

 tion of ice movement (10). 



History. In the early part of the last century, when attention 

 was first directed to these singular esker ridges, various explanations 



* I wish to express my appreciation of assistance by Professor Fairchild in connection 

 with this paper. He first suggested the subject to the writer as one worthy of study; he 

 has made many suggestions during the progress of the work; and has placed the facilities 

 of the Geological Laboratory of the University of Rochester at the disposal of the writer. 

 Finally he has contributed of his experience and time in the immediate preparation of the 

 paper for the press. 



