136 The American Geologist. February, is97 
The gorges of central New York, near lakes (Jaj'uga and 
Sene(ra, are in some cases much broader near their mouths 
than their heads. In some cases, notably in Estey's glen on 
the eastern side, and Taiighannock gorge on the western side 
of the southern end of lake (!ayuga, the present streams are 
engaged in cutting narrow gorges. Below the falls in these 
streams tlie valleys are broad, tliough still distinctly post- 
glacial gorges. The valley width is entirely out of proportion 
to the size of even the broadest torrents that now flow through 
them. It is as much out of proportion as the late summer 
stream is to the gorge valle}^ which the spring torrents are now 
carving in Greenland. 
It will not suffice to say that weathering and stream mean- 
dering have broadened the gorges in their lower reaches, for 
the change in width of the gorge is abrupt. Moreover in some 
of the smaller streams the broad lower gorge is now being 
littered by talus heaps, upon which trees are growing; and 
this shows that the water supply of the present is not only 
unable to cut so large a gorge, but cannot even dispose 
of the rock load furnished it by weathering. The condition 
reminds one of the abandoned outflow channel of lake Bonne- 
ville, and the shrunken streams of the far west. Once occu- 
pied by large streams, they are now becoming littered by the 
products of weathering from the valley sides. 
If this interpretation is correct, and the time near the close 
of the Glacial period was one of .greater water supply to the 
rivers, as we may well expect that it would have been, it is 
hazardous to draw conclusions from post-glacial gorges con- 
cerning the length of time that has elapsed since the Glacial 
period. This adds another important element of uncertainty, 
and in the case of Niagara it may well be sufficient to partly 
or entirely counteract the less rapid work that some believe 
was done during the time of diminished water suppl3^ Double 
the amount of water that flows over Niagara falls, even for a 
ver}^ short time, and the rate of work in gorge formation will 
certainly becoiiie greatly accelerated. 
