542 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



LEESVILLE ESKER. 



A short esker near Leesville, in Crawford County, about 3 miles west 

 of Crestline, is also described by Winch ell in his report on that county, as 

 follows: ^ 



At Leesville, in the southern part of section 7, Jackson, is a long and prominent 

 ridge of gravel popularlj^ denominated a " hog's-back. " The gravel ridge has been 

 in use for fourteen j'ears, during which time thousands of carloads have been taken 

 away for the Pittsburg, Fort Wayne and Chicago Railroad, but the part which 

 still remains rises iO feet above the surrounding level. A former spur from this, 

 known as the "Cleveland Hill," rose 20 feet higher, but it has been entire!}^ removed. 

 This gravel ridge is a little over half a mile long and runs nearly north and south, 

 or a trifle east of south. The "Cleveland Hill" tended more easterly along the 

 southern extremity. The main ridge lies on the observed line of superposition of 

 the Berea grit over the Bedford shale. The soft shale is in outcrop along the banks 

 of the Sandusky River, on section 12, within a quarter of a mile of the ridge, and 

 the sandstone is extensivelj^ wrought about half a mile east of the ridge. This ridge 

 is not bordered on both sides by low, swampy belts, as several others have been 

 observed to be, at least it is not on the eastern side. On the west side there is more 

 low ground, but the Sanduskjr River and a ravine tributary to it have somewhat 

 broken up its original surroundings in this respect. The country about is flat, or 

 nearly so, and the drift is made up of the common hardpan cla3^ The gravel of the 

 ridge embraces a great many bowlders about the size of 18 inches in diameter: some 

 also much larger. This conjunction of a gravel ridge pertaining to the drift with 

 ■ the line of outcrop of two formations, the one hard and the other soft, is not an 

 uncommon occurrence in northwestern Ohio. They are mentioned under the head 

 of "Drift" in the reports on Auglaize, Hardin, Allen, Morrow, and Delaware 

 counties, and seem to the writer to bear an intimate relation to the cause of that 

 deposit. Thej^ indicate that whatever that cause was it was susceptible of being 

 influenced bj^ the character of the underlying rock.^ 



The coincidence between the line of strike in the rock formations and 

 trend of the esker noted by Winchell is not to be found in all eskers. 

 While, therefore, it is not always necessary that there should be a line of 

 outcrop of two formations, one hard and the other soft, to cause the depo- 

 sition of an esker, it still may be true that the position of the stream which 

 produced the esker was determined by the resistance oftered by the hard 

 strata to the flow of the ice sheet as suggested by Winchell. 



CORRELATIONS. 



This moraine appears to be the equivalent of Winchell's St. Johns 

 moraine of the Maumee-Miami g-lacier, which when traced into Indiana is 

 called the Salamonie moraine. 



^ Geology of Ohio, Vol. II, p. 247. 



