JANUARY 18, 1901.] 
The lower courses of the Allegheny, 
Monongahela, Kanawha, Guyandot, Big 
Sandy and Kentucky rivers are character- 
ized by abandoned channels which generally 
range from 100 to 200 feet above the present 
streams. Generally these channels are 
deeply covered with silt, but sometimes the 
- rock floor is only partially obscured by a 
thin layer of sandand gravel. Thestreams 
which have forsaken these valleys have 
sought new routes, along which they have 
earved deep channels through the upland 
topography. Teays Valley in West Virginia 
is perhaps the most noted example, but the 
old channels at Carmichael and Masontown 
on the Monongahela River and at Parker 
on the Allegheny River are also well known. 
No reason has been assigned for the 
abandonment of these channels ; they can 
not be considered as ‘ox-bows,’ and they 
are all beyond the limit of glacial ice. The 
present hypothesis seeks to explain them 
through the breaking up of river ice and 
the formation of local ice dams, which were 
of sufficient height to force the water over 
the lowest divide in the rim of the basin 
and which persisted long enough for the 
stream to intrench itself in its new position. 
The paper was illustrated by many lan- 
tern slides of topographical maps. It 
brought on an extended discussion, because 
the Fellows were generally familiar with the 
subject, since for many years Teays Valley 
has not been omitted at a meeting, but has 
come up in one connection or another, and 
has grown to be a sort of geological Banquo’s 
ghost, that will not down. I. C. White op- 
posed the ice jams and argued in favor of 
one large dam produced by the continental 
glacier when it crossed the Ohio river. He 
emphasized the softness of the rocks at the 
headwaters of the southern tributaries and 
the harder ones further down. W. M. Davis 
suggested lakes as a possible obstruction 
which had developed cut-offs by gradually 
falling waters. G. K. Gilbert opposed the 
SCIENCE. 
99 
explanation by means of a glacial dam, and 
suggested a possible change in climate, with 
increasing cold and a filling of the valleys 
with ice, which brought about a rearrange- 
ment of the drainage. M. R. Campbell op- 
posed the explanation by lakes and by a 
glacial dam, because of the lack of uni- 
formity in the sedimentation which should 
appear with such an extended cause. A. P. 
Brigham called attention to the fact that 
the new courses assumed by some of the 
rivers were longer than the old and raised 
the point that ice jams ought to cut off and 
shorten meanders. M. R. Campbell ad- 
mitted the slightly longer courses in a few 
cases, but still supported the ice jam as 
against all the other causes suggested. 
The Alleged Parker Channel: Epwarp H. 
Witiams, Jr., Bethlehem, Pa. 
The paper was a brief one, which de- 
scribed one of the cases cited by Mr. Camp- 
bell, located at Parker, Pa. Instead of 
an old channel, the apparently abandoned 
detour of the Allegheny river was explained 
by the disappearance or effacement of the 
divide between the headwaters of two trib- 
utary streams. 
This general subject having been so well 
gone over, the above paper was not spe- 
cially discussed. 
Apparent Unconformities during Periods of 
Continuous Sedimentation: GrorcE B. 
SHattruck, Baltimore, Md. 
The paper was based on certain phenom- 
ena which the author had observed along 
the shores of Chesapeake Bay. Lenticular 
beds of black clay were found resting with 
apparent unconformity on older sediments 
and provided with cypress knees and other 
fossilized vegetation. The explanation ad- 
vanced was that minor stream valleys had 
been ponded during subsidence of the 
shore by bars formed across their mouths. 
Thus, while the sea crept inland and formed 
extended sediments, these ponded embay- 
