:i 1 s The American Geologist. March,i894 
and Thompson cols, formerly discharged northward to the lake Erie 
basin. A third natural section of the preeent Allegheny is found be- 
tween the Thompson col and the mouth of the Clarion river, where a 
col has apparently been surmounted by the present stream. Evidence 
amounting almost to a demonstration is found that this portion of the 
Allegheny had its discharge through a broad and meandering valley 
following in part the lower course of French creek and in part an 
abandoned channel to Carll s "Conneaut outlet'" and thence into the 
lake Erie basin. A possible fourth point of division of drainage sys- 
tems is placed on the Ohio river near New Martinsville, West Virginia, 
which would throw the lower Allegheny, Monongahela, and upper Ohio 
rivers into the lake Erie basin through the Beaver and Grand river 
basins. Concerning reversal of drainage in this section of the upper 
Ohio, the evidence collected, though suggestive, is considered too in- 
complete to justify any firm opinion. This hypothesis differs from the 
one recently advocated by Dr. Foshay in placing the divide some fifty 
miles farther south, in giving the outlet a slightly different course 
from the Beaver to the Grand river basin, and in restricting the 
applicability of the hypothesis to the elevated base plane or to the 
upper part of the trench cut in it, data concerning the rock floor hav- 
ing been collected by Mr. R. R. Hice which demonstrate its inapplica- 
bility to the lower trench. 
The transgression of cols and the development of pseudo-cols through 
shifting of the summit of the rock floor by erosion was briefly touched 
upon. Some cols have shifted but little, w T hile others may have passed 
up the river many miles. The supposed col near the mouth of the 
Clarion is thought to have shifted its pseudo-col about ninety miles to 
the vicinity of Warren, where it has become coalescent with that of 
the Thompson col. 
The importance of considering each section of the Allegheny by it- 
self was urged, since in preglacial time it had an independent history 
and even in glacial times differed in some respects from its neighbor. 
The glacial drift of the region is separated into two distinct parts: 
(1) the attenuated border; (2) the series of moraines. The recent studies 
have shown that the high level gravels of the river valleys have a def- 
inite relationship to the attenuated drift, a relationship essentially the 
same as that of the moraine-headed terraces to the moraine. Since the 
gravel trains connected with the attenuated drift-sheet stand at alti- 
tudes far above the adjacent moraine-headed terraces, the conclusion 
cannot well be avoided that great erosion occurred between the two 
gravel depositions, consequently a great break in the glaciation. This 
being the case, the attenuated drift should no longer, in that region at 
least, be considered a dependency of the moraine which it borders. 
Terraces and gravel deposits occur along the Allegheny at levels be- 
tween the high gravels and the moraine-headed terraces, but they com- 
monly occupy such situations on sloping points, etc., as would be favor- 
able to deposition during the progress of valley cutting as well as dur- 
ing valley tilling. As such they do not furnish decisive evidence as to 
whether they are remnants of early gravel, or of the possible valley til- 
ling between the early and late gravels, or are incidents of valley cut- 
ting. In the lower Allegheny region no place was found, after careful 
search, where abandoned ox-bows or deep recesses of the valley contain 
a filling of early gravels comparable in depth to the present trench. On 
the upper portions of the Allegheny which were interpreted to have 
led directly to the Erie basin the broad preglacial base planes lie nearly 
as low as the present streams and trenching is not carried far below 
them. The small amount of trenching there strengthens the negative 
evidence against deep preglacial trenching on the lower Allegheny. 
In interpreting the phenomena of this region the hypothesis of a 
eirjgle continuous glaciation is necessarily excluded because of the 
