2S4 'The Aiiiericdji (reolotjiaf. Ndvc'ininT, i.v.ts. 
thickly strewn witli these gravel and boulder remains and a 
sand deposit occurs similar to that at AVaco. The boulders 
occur to a hight of 200 feet above the river. With one excep- 
tion, all the materials seem to be of Carboniferous origin. The 
exception noted was a hard quartzite boulder measuring 14 by 
8 by 5 inches; and it had every appearance of the Canadian 
([uartzites found so abundantly in the beds of southern Ohio' 
streams near the margin of the drift. The hight of the hills, 
850 feet above tide, has not been quite great enough to render 
their tops entirely free from pebbles. 8ixty-tive miles farther 
on in the sinuous course of the stream (25 miles in an air 
line), at Tyrone on the western flank of the anticline, where 
the river, after rounding the anciently obtruded barrier, again 
resumes the wonted course of Kentucky rivers — toward the 
northwest — the same high level conglomerate pebbles w^ere 
sought for and found at their proper hight. The evidence 
seems conclusive, that the Kentucky river, as its sister river 
the Licking, was within comparatively recent times flooded 
out over its banks to a level that was, for its lower course, 
from 300 feet to 350 feet above its present channel, or to some- 
thing like 875 feet above sea level. 
The glacial dam hypothesis, which has been urged to ex- 
plain the terrace phenomena of the Ohio River valley above 
Cincinnati, might also seem the most reasonable one here ; and 
if we had only the Kentucky river to deal with, "lake Ken- 
tucky" might be added to "lake Ohio." The terminal mo- 
raine is platted by Wright as crossing into Trimble county. 
Ky., below Carrollton. This could give us an ice dam block- 
ing the mouth of the Kentucky as etfectually as did that at 
Cincinnati the mouth of the Licking and the upper course of 
the Ohio. We may, upon this assumption, by tracing the 
contour of 875 feet, approximately determine the outlines of 
this "lake Kentucky." It would be long and narrow, hardly 
getting outside the confines of the strip of river hills about 
four or five miles back on either side, because the Kentucky 
river for a great part of its course flows far below the present 
level of the country in a carion-like gorge. P^vidence may be 
forthcoming that the river was flooded to a higher level than 
this, as high as Prof. Wright claims for his lake Ohio, in 
which case the two lakes were probabl}^ continuous, at least 
