478 GLACIAL FOKMATIONS OF ERIE AND OHIO BASINS. 



TOPOGRAPHY. 



The contours of this moraine, as ah^eady observed, are of a smooth and 

 gentle type compared with those of the knolls and ridges of the main 

 inorainic system. The main ridge rises somewhat abruptly above the outer 

 border plain, but the undulations on its crest and slopes are low and gentle, 

 seldom exceeding 16 feet in height. Basins are not a common feature 

 except locally, as noted below. 



At the northeast end in Logan County, Ohio, and westward from that 

 point, in the portion of the moraine east of the Great Miami, there are 

 many basins, some of which have abrupt bluff-like borders, while others 

 are saucer-like, with a gentle rise on their borders. This portion of the 

 moraine has not so well defined k main ridge as the portion farther west 

 and has, on the whole, sharper contoui-s. The knolls, however, commonly 

 fall between 10 and 15 feet and seldom exceed 20 feet in height. The 

 Miami River enters an elevated plain just west of De Graff, the altitude of 

 which is 50 to 60 feet higher than portions of the moraine near De Graff, 

 but the surface is remarkably free from di-ift knolls. Just west of Tileton 

 and north of Port Jefferson the moraine reappears in considerable strength, 

 there being a ridge or range of sharp knolls whose highest points stand 

 about 30 feet above the bordering plains. This rang-e continues sharp for 

 only a mile or so, when the moraine assumes its usual surface expression, the 

 knolls being 10 to 15 feet or less in height and the tendency to ridging not 

 conspicuous. The little ridging that occurs commonly, though not always, 

 takes the trend of the basement ridge which constitutes the bulk of the 

 moraine. 



A thin sheet of drift without definite ridging appears to have been 

 deposited at this time on the plain east of the Miami, opposite Sidney, there 

 being a small tract there with undulatory surface, and on its east border an 

 abrupt descent of 10 to 15 feet to the outer border plain. 



In the valley of Loramie Creek, near Lockington, basins as well as 

 knolls are displayed. The knolls have a height of 10 to 20 feet and their 

 contours are sharper than are those of the knolls on adjacent uplands. 



For a few miles southwest from Loramie Creek the moraine is below 

 its average strength and has not a continuous ridge, though a few short 

 ridges with northeast to southwest trend occur. On the divide between the 



