lS93-] UPHAM ESKERS NEAR ROCHESTER, N. V. 183 



the Mount Hope Cemetery and the Genesee river and farther to the 

 west, the material of the ridge is largely till, which shows that low 

 portion to be a marginal or interlobate moraine ; but the high range 

 of the Pinnacle hills from Brighton to the Mt. Hope Cemetery is 

 clearly an esker, t,}^ miles long, consisting of interbedded gravel and 

 sand, here and there enclosing boulders, sometimes in surprising 

 abundance, but containing no till in the extensive sections nor on its 

 surface. 



The width of this hill range is mostly about a sixth of a mile, 

 but varies from a tenth to a half of a mile. Along its whole extent 

 it is a single range, nowhere presenting a combination of parallel 

 series of hills ; but, in some parts, especially in the Highland Park 

 and near the reservoir, it is incised on each side by ravines between 

 spurs and outlying hillocks of the main belt, and its top is occasion- 

 ally very uneven in contour, with infrequent bowl-shaped hollows lo 

 to 50 feet below the surrounding surface. The profile of its crest line 

 undulates in an irregular way, generally varying 50 to 100 feet in 

 height upon each mile or half mile ; and it nowhere maintains a level 

 course for any considerable distance. In the vicinity of the Pinnacle 

 and in many other places, the slopes on each side are very steep, 

 ranging to a maximum of about 30 degrees ; and the crest line has 

 occasional slopes of half this steepness. More commonly, however, 

 the slopes vary from 6 to 15 degrees, having from 10 to 25 feet of 

 ascent in a distance of 100 feet. 



When my first contribution to geology was published, sixteen 

 years ago, "On the origin of Kames or Eskers in New Hamp- 

 shire," (') these classes of the modified drift, produced jointly by the 

 ice-sheet and the water of its melting, had not been discriminated 

 from each other. Every knoll, hillock or hill, short or long ridge, or 

 series or network of ridges composed of irregularly and often anti- 

 clinally bedded gravel and sand, retaining nearly the original form in 

 which it was accumulated, was then called interchangeably a kame, 

 esker, or as, or a series of kames, eskers, or asar. The first of these 

 terms is of Scottish, the second of Irish, and the third of Scandina- 

 vian origin, the last being Anglicized to osar, with osars as its plural 

 form. It is found very desirable, however, to subdivide these gravel 

 and sand accumulations into two classes, as proposed by McGee (^) 

 and Chamberlin, (^) giving to the hillocks and short ridges the name 



(i.) Proc. A. A. A. S., Vol. XXV, for 1876, pp. 216-225. 



(2.) Report of the International Geological Congress, second session, Boulogne, 1881, p. 621. 

 (3.) U. S. Geological Survey, Third Annual Report for 1881-82, p. 299 ; Am. Jour. Sci III 

 Vol. XXVII, 1884, p. 389. 



