764 GEOLOGY OF OHIO. 
at least five hundred or six hundred feet in depth, this being the height 
of the watershed between the Licking river, in Kentucky, and the Ohio 
river on either side. Such an obstruction would set back the water of 
the Ohio far up into the valleys of the Allegheny and the Monongahela, 
submerging the site of Pittsburgh three hundred feet. (The low-water 
mark at Cincinnati is 441 feet above the sea, that of Pittsburgh, 715 
feet). It remains to be seen how much light this may shed upon the 
terraces which mark the Ohio and the tributaries in Western Pennsyl- 
vania. 
We learn from Prof. I. C. White, of the Pennsylvania Geological 
Survey, that the terraces of the Upper Monongahela correspond very 
closely in height to what we should expect if the ice-barrier at Cincin- 
nati were such as I have supposed. In the vicinity of Morgantown, 
West Virginia, terraces of clay, sand, gravel, boulders, drifted logs, 
and other rubbish occur in the valley of the Monongahela up to an 
elevation of 1,065 feet, but above that elevation not a single rounded 
and transported boulder has ever been found. This corresponds very 
closely to the height of the barrier indicated by the glacial deposits 
south of Cincinnati. Similar terraces are found up the Allegheny and 
its tributaries to about the same height. 
According to Mr. White, also, the glacial dam at Cincinnati pre- 
sents a complete explanation for the origin of Teaze’s valley, an ancient, 
deserted river channel, 20 miles long, and one to two miles wide, which 
leaves the great Kanawha 15 miles below Charleston, W. Va., at Scary, 
and passing through Putnam and Cabell counties, extends to the valley 
of Mud river, a tributary of the Guyandotte which empties into the 
Ohio at Huntington. 
This valley, though having an elevation of 200 feet or more above 
the Kanawha, is filled to a great depth with rounded boulders of sand- 
stone, chert, cannel coal, and other trash, which have been plainly trans- 
ported down the Kanawha from above Charleston, so that although it 
was clearly seen that the water of the Kanawha had once found an out- 
let to the Ohio by the way of this valley and the Mud and Guyandotte 
rivers, yet why this ancient channel should have been abandoned for 
the present much more circuitous one had always remained a mystery 
until the key was furnished by the discovery of the great ice dam at 
‘Cincinnati ; for it is now clear that while such a barrier would set back the 
water of the Kanawha until rising above the divide which had previously 
