Jan., 1908.] An Esker Group South of Dayton. 233 



General Discussion of Eskers. Much question and dispute 

 has arisen in the past concerning the terminology^ for certain 

 ridge-like products of glaciation, but the designation "Esker" 

 is generally applied by American Geologists to lines of debris 

 presumably aggraded by streams between walls of ice. Though 

 the theory of deposition in sub-glacial tunnels^ holds the greatest 

 credence today, the en-glacial and super-glacial or various com- 

 binations of the three theories have been offered as plausible 

 explanations in specific instanced For convenience this article 

 assumes in the beginning that the Dayton ridges are eskers, and 

 that they were formed in sub-glacial tunnels. 



Preliminary Description of Region. (Fig. 1.) The northern 

 end is known locally as "The Bluffs." These trend east-north- 

 east to west-southwest about half a mile presenting an abrupt 

 slope considerably over one hundred feet high toward the valley 

 of Dayton to the north. The Miami canal runs along the slope 

 not far from its bottom, and below this at the base of the Bluffs 

 flows the Great Miami River. The topography of this and also 

 of the western half of the area presents a beautiful study in 

 kames; mounds and basins'* are abundant. The inounds or 

 knolls frequently show a tendency toward alignment producing 

 ridges. The eskers indicated on the map constitute the eastern 

 boundary of this kame area. They overlie their base like rail- 

 way embankments crossing uneven topography.^ From the 

 region of the Bluffs they proceed southward about a mile ending 

 bluntly on the Miami Valley. The crest-lines are sinuous in both 

 vertical and horizontal directions, though the general course is in 

 almost a straight line. The esker form is at times modified by 

 knolls, rarely by distinct gaps. The crests are narrow and the 

 sloping sides steep, apparently taking the angle of repose normal 

 to the debris of which they are composed. Both the eskers 

 and the kamy topography westward rest upon a base rising above 

 the valley of the Miami. To the southeast, across the road- 

 way from the southern ends of the eskers the kamy topography 

 continues for about a mile. This topography shows a curious 

 branching and anastomosing of ridges. Though at present sug- 

 gestive of kames it is quite possible that it represents modified 

 glacial phenomena of other than kame origin. A more elaborate 

 study of this will be made in a future paper. 



5. G. F. Wright, The Ice Age in North America, (1891), p. 296. 



G. H. Stone, Monograph XXXIV, U. S. Gaol. Surv., (1899), pp. 35. 359. 

 W. C. Morse, The Ohio Naturalist, Vol. VII, (1907), pp. 63-65. 



6. Chamberlin & Salisbury, Geology, (1906), Vol. Ill, pp. 373-7. 



7. W. M. Davis, Proc. Bos. Soc. Nat. Hist., Vol. XXV, (1892), pp. 477-99. 



J. B. Woodworth. ProcBos. Soc. -Nat. Hist.'. Vol. XXVI, (1894), pp. 197-220. 

 O. H. Hershev, Am.. Geol.,Vol.-XIX, (1897), pp. 197-209, 237-253-.- 

 W. O. Crosby, Am. Gaol., Vol. XXX, (1902), pp.-l-39. 



8. T. C. Chamberlin, loc. cit., p. 334. 



9. Chamberlin & Salisbury, loc. cit., p. 375. '.:■.-• ■ . ■ ■ ■ 



