s 
THE GEOLUGICAL HISTORY OF NEW YORK STATE SI 
territory at the expense of the Susquehanna because the short, 
swift tributaries of the Mohawk, which flow northward over the 
Helderberg escarpment, are cutting down their channels rapidly, 
while their headwaters are migrating southward into the territory 
of the Susquehanna. A great network of large and small streams 
tributary to the upper Susquehanna drain a considerable portion of 
south-central New York, there being no single great master stream 
in this region because the rock formations are so nearly horizontal 
and are so much alike as regards resistance to erosion. 
The Delaware system has had a history practically the same as 
that of the Susquehanna, except that it never drained any of the 
region north of the Mohawk. 
The present ruggedness of the Catskills is largely, if not alto- 
gether, due to the production of deep channels which have been 
cut into the region upraised at the time of the uplift of the great 
peneplain by the headwaters of the Delaware, Schoharie creek 
(north-flowing), and the smaller streams flowing across the steep 
eastern front of the mountains. 
During Tertiary times Lake Champlain was certainly not in 
existence, but the great depression was there and was no doubt 
largely developed or at least increased in depth by the settling of 
earth blocks during the time of extensive faulting at the close of 
the Mesozoic or beginning of the Cenozoic. The depression is 
essentially a fault trough. The major stream occupying this valley 
flowed northward and in late Tertiary time, at least, the divide 
between the drainage of this and the Hudson valley passed between 
Glens Falls and Whitehall, and through the present position of 
the “ Narrows” of Lake George, the lake, of course, not then being 
in existence. 
Drainage of New York in the Tertiary. The outline of the 
probable drainage condition of western New York during the 
Mesozoic has already been given, and now as we attempt to restore 
the drainage conditions of the Tertiary, we must admit that some 
problems yet remain unsolved. Lakes Ontario and Erie certainly 
were not in existence. Streams flowed through these basins, which 
were not as deep as they now are. The bottom of Ontario is as 
much as 491 feet below sea level, while its surface lies at an alti- 
tude of 247 feet, and the altitude of Erie is 573 feet while its 
greatest depth is 204 feet. The explanation of the increased depths 
of the basins is given on a later page. The question now arises, Did 
the waters from western New York drain westward or southwest- 
ward and into the Mississippi, or northeastward through the St 
