50 THE PREGLACIAL DRAINAGE OF OHIO. 



SO much with their individuahty — as that they are parts of a 

 whole, converging to a common axis of drainage, and this axis 

 is the trough between the Coal hills and the Waverly from 

 Loudonville to Lake Erie. The P. F. W. & C. R. R. follows 

 this trough from Loudonville to Wooster, and its record of levels 

 will tell us the grade of descent. Mansfield is 578 feet above 

 the Lake, Lucas 518, Perrysville 433, Loudonville 412, Lakeville 

 378, Shreve 352 and 'Wooster 342 above Lake Erie, making a de- 

 cline of 236 feet between Mansfield and Wooster or about 6 

 feet to the mile. 



This old waterway is clearly defined from Loudonville to 

 Wooster, and from there is easily traced by Orrville and Chip- 

 pewa Lake to Rocky river ; that portion between Loudonville and 

 Wooster is bounded by high and rocky hills of Waverly on the 

 northwest, and Carboniferous conglomerate on the southeast; 

 and the channel ran the entire distance, exactly between these 

 too widely different geologic formations. It is filled to varying 

 depths with gravel, and sand, and clay; its surface presenting a 

 broad and fertile valley, with soft undulations between kames, 

 kettle holes, and cranberry marshes. 



Its rock floor, however, is of greater interest to the student 

 of preglacial water ways, and, beginning at Loudonville, a drilled 

 well shows this rock floor to be 150 feet below the village, mak- 

 ing our starting point 262 feet above Lake Erie. Next, near the 

 bridge over Lake Fork, where a preglacial channel comes in 

 from Mohecanville, the rock floor is determined by the chain of 

 lakelets that marks its course; their depth being about 130 feet, 

 and the surface elevation here being 375 feet gives the rock bot- 

 tom 245 feet above Lake Erie. Applying the same rule at 

 Odel's Lake, through which the axial channel passes, I find 

 rock at 228 feet ; and at Big Prairie with a surface elevation of 

 390 feet, a drilled well shows 176 feet of drift, making the floor 

 214 feet above Lake Erie. 



Near Alligewi (Custaloga) Junction between Big Prairie and 

 Shreve, where the precursor of the Lake Fork, that tore out a 

 channel 10 miles long, i^ miles wide and 400 feet deep — counting 

 from hill tops — thus creating the "Big Meadow" of the Indian and 

 the "Big Prairie" of the Pioneer, entered the axial channel by 



