540 GLACIAL FORMATIONS OF EKIE AND OHIO BASINS. 



degree of assorting- and force of ciTrrent, and also in the existence of an 

 excavated trough, strong evidence in support of the hypothesis of the 

 subglacial origin of the esker. By this it must not be understood that all 

 eskers are thought to have been formed in subg'lacial channels; indeed, it 

 seems not improbable that in some instances they may have had a super- 

 glacial origin, having apparently been formed in a channel open above to 

 the air. Possibly cases occur in which an esker is in part superglacial 

 and in part subglacial in its origin, the stream which formed it being for a 

 portion of its course on the surface or in a deeply covered tunnel or chasm 

 in the ice, while later, or upon approaching the ice margin, it flowed on 

 the ground beneath the ice and excavated the trough. In places where the 

 current was not swift enough to carry onward all the material it deposited 

 the material for the ridges. In some esker systems a delta or fan was devel- 

 oped at the end nearest the margin of the ice sheet, but in the Taylor Creek 

 esker no such delta appears. The tracts where the esker terminates, as well 

 as those bordering it, are underlain by till, and show no more assorted 

 material than portions of the moraine not associated with an esker. 



RICHWOOD ESKER. 



In the village of Richwood, in Union Count}^, there is a low gravel 

 ridge of the esker type. It is 10 to 15 feet high where most prominent, 

 and 30 to 60 yards w^de. It sets in about one-half mile north of Richwood 

 station, and runs in a course S. 20° E. to the business portion of the village. 

 From Richwood southward no well-defined ridge appears, but a nearly 

 plane gravelly belt in line with the ridge continues to Fulton Creek, li miles 

 south of the village. The bordering tracts are till. The relation between 

 this level gravelly belt and the esker is thought to be somewhat close, both 

 being deposited probably by a glacial stream, the esker perhaps in a nari'ow 

 tunnel and the level-surfaced gravel in a broad one. The thickness of 

 drift in Richwood along the line of this gravelly belt is only about 30 feet. 



RADNOR ESKER. 



A gravelly belt formed along the Scioto River Valley from Prospect 

 southward to the moraine has been well described by Winchell, as follows:^ 



A singular line of gravel knolls and short ridges pertaining to the glacier drift 

 crosses Radnor Township, coming into the county from the north at Middletown 



1 Geology of Ohio, Vol. II, 1874, pp. 304-306. 



