138 THE JOURNAL OF GEOLOGY. 



Re-elevation of the la?id. Between the deposition of this 

 silt and the formation of the outer moraine of the later drift, the 

 altitude appears to have become about as great as at the present, 

 since, as shown below, the gravels deposited at that time along 

 valleys leading away from the ice margin bear witness of vigor- 

 ous drainage. 



Outer moraine of the later drift. Since the position of this 

 moraine is indicated on the accompanying map, it need not be 

 outlined. It should, however, be stated that this moraine is 

 overridden by a later one a few miles east of Hillsboro, Ohio, 

 and has not been recognized in the eastern part of the State. 

 The moraine consists of a ridge of drift one to two miles or more 

 in width, standing, as a rule, but twenty to forty feet above the 

 outer border plain. Its surface is gently undulating, there being 

 but a few sharp knolls or ridges, such as characterize the surface 

 of a later series of moraines described below. It is composed 

 mainly of till, though gravel deposits are not infrequent, either 

 in the low knolls or in beds or pockets incorporated in the body 

 of the drift. 



Striae are numerous in the district immediately north of this 

 moraine, and since the usual bearing is toward the moraine and 

 not toward the glacial boundary, it seems evident that they were 

 produced at the time of the later invasion. Some striae near 

 Cambridge City, Indiana, appear to be out of harmony with the 

 ice -movement of the later invasion, and may, therefore, be older. 



The older drift was but partially removed by this later inva- 

 sion, and it is frequently encountered in wells and exposed in 

 bluffs of streams. It is harder and dryer than the newer drift. 

 In a few places, notably at Marshall and Martinsville, in High- 

 land county, and in the vicinity of Wilmington, in Clinton 

 county, a black soil is found at the base of the newer drift. I 

 have seen it only at Wilmington, but Prof. Orton, in his report 

 on Highland county, calls attention to its occurrence at Marshall, 

 and I was told by well diggers of its occurrence in Martinsville. 

 In Wilmington it is exposed in a railway cutting near the pub- 

 lic school building, in the west part of the village. It consists 



