398 GLACIAL FORMATIONS OF EKIE AND OHIO BASINS. 



large knolls, the height commonly falls below 25 feet. Drift knolls 10 to 

 15 feet high occur on the elevated tract east of Lattas, in the vicinity of 

 the Greenfield and Chillicothe pike, but such features are not common on 

 the high ridges, the sharply defined morainic knolls in this vicinity being 

 confined mainly to lowlands and valleys. 



Of the four members that appear in the southwest portion of this 

 morainic system, the outermost one is by far the strongest. Along Paint 

 Greek, near the mouths of Rocky Fork and Rattlesnake Creek, and thence 

 up the west side of Rattlesnake Creek for several miles, this member is 

 characterized by numerous large, gravelly knolls, manj" of which are 30 to 

 40 feet, and a few 75 to 100 feet in height, while among them are many 

 smaller ones. The aggregation is close and the contours are sharp, so 

 that an exceptionally rugged topography is presented. From northern 

 Highland County northward large knolls are infrequent, but closely aggre- 

 gated knolls and ridges 10 to 25 feet or more in height occur. Besides 

 having these minor I'idges and knolls, the moraine carries a basement ridge 

 with well-defined relief of 20 to 30 feet, so that one standing at the base of 

 the knolls is somewhat above the outer border plain. The outer members 

 of this series display generally a ridge with well-defined crest on which the 

 small knolls and ridges are deposited. The height of these knolls seldom 

 exceeds 25 feet and is" commonly only 10 to 15 feet, but they are so closely 

 aggregated as to make the belt conspicuous. The intervening tracts between 

 the several members are plane or very gently undulating, with scarcely a 

 knoll worthy of notice. 



At their northei'n ends these several members do not at once form a 

 bold moraine, but for a space of 10 miles or so the features are rather more 

 subdued than in the separate members. But in northeastern Clark County 

 the moraine assumes greater prominence, and from there northward through 

 Champaign and Logan counties it exhibits as strong and characteristic 

 morainic features as anywhere in its course. There are winding and inter- 

 locking ridges ranging in height from 10 feet up to 75 feet or even more, 

 among which numerous basins are inclosed. The slopes of the larger knolls 

 are frequently dotted with small knolls and ridges, and cai-ry an occasional 

 basin. Near Mechanicsburg the moraine rises abruptly on its eastern 

 border to the unusual height of 75 or 100 feet, and a series of ridges whose 

 height is 30 to 50 feet and whose contours are exceedingly sharp, lead 



