WABASH MORAINE. 555 



Ridge," which stands nearly 50 feet above the surrounding country. Also 

 in southern Dekalb County, in the southwest part of T. 33, R. 13 E., knolls 

 30 to 40 feet in height occur. East of this prominent part of the moraine 

 and near the line of Allen and Dekalb counties several marshes and sloughs 

 were noted. They are narrow and look like obstructed valleys, though no 

 connection with modern valleys could be found. East of these depres- 

 sions is an undulatory till tract presenting oscillations of 10 to 20 feet in 20 

 to 40 rods. 



In a trip from Butler south to the St. Joseph River near the State line 

 a few swells 10 to 16 feet high and shallow basins 3 to 5 feet deep were 

 noted, the sharpest knolls being in sees. 23 and 24, T. 34, R. 14 E. But 

 slight though the undulations are they furnish a decided contrast to the 

 very flat surface north of Butler and between Butler and Auburn, where 

 a hummock or rise of ground as great as 5 feet in height is rare. 



THICKNESS OF THE DRIFT. 



In each of the moraines under discussion the thickness of the drift is 

 perceptibly greater than on the plane tracts on either side, the difference 

 being measured by the relief of the moraines. The relief, as has already 

 been stated, ranges from 16 up to 50 or 60 feet, but the average relief is 

 probably about 30 feet. The relief represents the increase in thickness 

 beneath the crest, but on the slopes the amount of increase would be less. 

 Assuming for each of the moraines an average breadth of 1^ miles the 

 average thickness of the drift properly included in them would be not more 

 than 20 feet. 



The amount of drift deposited by various invasions and covered by 

 this moraine ranges from 20 feet or less up to about 400 feet. The average 

 thickness is probably less than 100 feet from the old lake outlet westward, 

 but is much more than 100 feet from the outlet northward into Michigan. 

 The thickness in the coalesced portion of this morainic series in northern 

 Ohio is somewhat less than in the portion where the moraines are distinct 

 in western Ohio, the amount on the elevated hills and ridges being seldom 

 so much as 40 feet. 



STRUCTURE OF THE DRIFT. 



This moraine is preeminently a till tract, there being but few gravel 

 knolls. It is known tliroughout much of its course as the "White oak 

 ridge," since the forests along it are largely oak, while the bordering 



