430 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



consists of a main ridge that stands 20 to 40 feet above the plain on its 

 eastern border, and 40 to 60 feet above the Scioto River, which flows 

 along its west side. In several places ridges separate from the main ridge 

 and return to it one-fourth mile or so south, making a nearly complete 

 connection with it at each end. In some cases very sharp basins are 

 inclosed between the main ridge and these side ridges. Two were observed 

 that are about 40 feet deep. One of these was dry, tlie other contained 

 a pond. The ridges on each side have sharp slopes of fully 30°. These 

 slopes afford a means for calculating the amount of filling the basins may 

 have received since the ice retreated. By continuing the slopes down- 

 ward beneath the basins from opposite sides, they would meet at a. point 

 about 20 feet below the present surface, which represents the possible amount 

 of filling. It could not well be greater and it may have been less, espe- 

 cially if the basin originall}^ was somewhat flat in the bottom; but, granting 

 a filling of 20 feet, it follows that the amount is small for such steep slopes 

 of loose material to have contributed, and it aff'ords evidence in favor of 

 the brevity of postglacial time. 



At its southern end the esker branches, like the mouths of a stream in 

 a delta, and is lost in a marshy plain. Low ridges or knolls occur in this 

 plain south of the terminus of the esker proper, and on the border of the 

 plain, in the northern part of Circleville, there are gravel knolls which may 

 bear some relation to the esker, though they are situated in the moraine. 

 The termination of the esker proper is but a mile or so from the moraine. 

 In all probability the esker was formed before the ice sheet had withdrawn 

 from the moraine. 



But few exposures occur to show the structure of the esker. A well 

 at R. I). Harmon's residence, on the crest of the esker, about 3 miles north 

 of Circleville, penetrated 60 feet of sand and gravel and obtained water at 

 about the level of the Scioto River. The water contains sulphur in such 

 large amount that stock will not drink it. The sulphur is probabl}' from 

 sulphuret of iron contained in fragments of shale. Mr. Stevenson has a 

 well near the base of the ridge, a short, distance north of Harmon's, which 

 penetrated 6 or 8 feet of clay and then 80 feet of gravel before obtaining 

 water, probably reaching the level of the Scioto. In places the ridge is 

 capped by a few feet of clay, through which pebbles are scattered, but 

 quite as often the gravel is at the surface. At a slight exposure near 



