UNION MORAINE. 477 



correlation, it is suggested that the ice margin, at the time it was occupying 

 the line between Muncie and Peru, held, farther east, a position essentially 

 coincident with the Union moraine, and that, in its later shiftino's, the ice 

 margin fell short a few miles of reaching the western ^^ortion of the belt 

 but again occupied the portion from Delaware County eastward, and at 

 that time formed the well-defined ridges which distinguish this eastern 

 portion from the western. These ridges in Delaware County, Ind., become 

 associated with the Mississinawa moraine, and are also combined with that 

 moraine on the borders of the Miami and Scioto basins in west-central Ohio. 



From Delaware County, Ind., eastward the Union moraine, through- 

 out much of its course, has an abrupt outer border relief The inner 

 border relief is somewhat less than that of the outer border, there being 

 an accumulation of ground moraine material north of the terminal ridge 

 There is usually a descent of 10 to 20 feet from the crest of the moraine 

 to the inner, border plain, though in places there is no perceptible descent 

 on the inner border, and the limits of the moraine are best determined by 

 the change from undulating to plane topography. 



RANGE IN ALTITUDE. 



The Ohio portion of the moraine has but little range in altitude. Its 

 highest points, which are in western Darke County, opposite the highland 

 tracts of Logan County, stand 1,125 to 1,150 feet above tide, while its lowest 

 points, which are along the southern curve of the loop between Grreenville 

 and the Great Miami River, have an altitude of about 1,000 feet. In Indiana 

 there is a gradual descent from 1,125 feet at Union on the State line 

 to about 925 feet at the junction with the Mississinawa moraine. In the 

 feebly ridged tract outside that moraine the altitude of the uplands in the 

 vicinity of the Wabash River is 750 to 800 feet, while the valley of that 

 portion of the river stands only 660 feet above tide. 



The rock surface has a range in altitude fully as great as the di'ift 

 surface, there being as great an amount of drift at points where the moraine 

 stands lowest as where it stands highest. 



