166 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



the most plainly marked instances of the crossing of an old divide to be 

 found in northern Ohio. The Tuscarawas, whose valley above the mouth 

 of One Leg Creek is fully one-half mile in average width, enters a gorge 

 below the mouth of this creek which is scarcely twice the width of the 

 stream, or but 150 to 200 yards. The gorge is a winding channel about 

 4 miles in length, which was probably mainly drained southward to the 

 Lower Tuscarawas, for the old divide appears to be within a mile of its north 

 end. In this gorge, 1 to 2 miles below the mouth of One Leg Creek, the 

 river is running on the rock floor. Above the gorge, at the mouth of One 

 Leg Creek, the rock floor is known to be more than 100 feet below the stream 

 bed, a boring on its flood plain having failed to reach rock at a depth of 130 

 feet. A few miles below the gorge, at Canal Dover and New Philadelphia, 

 borings have shown the rock floor to be nearly 150 feet below the stream 

 bed. There is, therefore, not only the marked constriction of the valley, 

 but also the presence of a concealed rock divide to prove that the Tuscara- 

 was is there opening a new channel. 



The small size of this gorge compared with other channels across old 

 divides in this part of Ohio is a matter on which further light is needed. 

 The gorge is much smaller than the part of Sugar Creek Valley near 

 Strasburg, which, as noted above, is thought to have been opened by a 

 reversal of drainage. These disparities in size may prove to be due sim2Dly 

 to difference in resistance afforded by the rocks in the two localities, for 

 the valleys of that region present surprising variations in width, which seem 

 due solely to rock texture. For example, the valley of One Leg Creek, 

 whose usual width in its lower course is less than one-half mile, expands 

 near New Cumberland to a width of more than a mile and then contracts 

 near its mouth to a width of about one-third of a mile. The valley of 

 the Tuscarawas at Canal Dover is exceptionally broad, being more than a 

 mile in width, yet it appears to be the headwater portion of the old Lower 

 Tuscarawas. In case rock texture proves inadequate to account for the 

 exceptionally small size of this gorge across the old divide, it becomes nec- 

 essary to consider whether its opening does not date from the Wisconsin 

 stage of glaciation, while the opening of the broader channel in the lower 

 course of Sugar Creek dated from an earlier invasion. The consideration 

 of this question would also carry with it an inquiry into the question whether 

 the lower course of Sugar Creek may have furnished the southward line of 



