G. F. Wright—Glaciated Area of Ohio. 49 
the hills for three or four miles southeast, and four or five. hun- 
dred feet above the river, and here, as at Flag’s Spring, on the 
other side of Cincinnati, the formation marks the true glacial 
boundary. It would seem, however, that the ice nowhere ex- 
tended into Kentucky more than four or five miles from the 
river. Near Burlington, in Boone county, on one of the tribu- 
taries to Gunpowder Creek, which flows to the south, and whose 
source is between five hundred and six hundred feet above the 
river, there is a noticeable collection of granitic bowlders mark- 
ing the southern extent of the ice. Fifteen or twenty of these, 
from one to three feet in diameter, were counted in a small space. 
Three or four of these were composed of a metamorphic con- 
glomerate containing jasper pebbles peculiar to the eastern 
shore of Lake 
sub-glacial channel was kept open. It would scarcely seem 
possible that this was the case at Cincinnati; for the trough of | 
the Ohio is considerably wider than that of the Upper Alle- 
ghany, and not far from fifty miles of the Ohio: Valley, border- 
ing Campbell, Kenton, and Boone counties, Ky., must have 
been covered by glacial ice. Probably, fora short time, the ice - 
at Cincinnati formed an obstruction to the channel. But what 
was the course of its overflow I am not prepared to say. The 
obstruction must have been at least five hundred or six hun- 
dred feet in depth, this being the height of the watershed be- 
tween 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 Alleghany and the Mo- 
nongahela, submerging the site of Pittsburg three hundred feet. 
(The low water mark at Cincinnati is 441 feet above the sea, 
that of Pittsburg 715 feet.) It remains to be seen how much 
light this may shed upon the terraces which mark the Ohio and 
its tributaries in Western Pennsylvania. 
TERRACES, . 
facts connected with each stream mentioned. 
streams in their course through the glaciated area have much 
more gentle current, and much less distinct valleys, than in the 
unglaciated area, and the point where a stream emerges from a 
glaciated area is pretty sure to be marked by terraces of excep- 
tional height, ad exceptionally coarse in their composition, _ 
Am. Jour. Sor.—Tarep Sunres, Vou. XXVI, No. 151.—Juy, 1883. 
Bee 
