THE GEOLOGICAL HISTORY OF NEW YORK STATE 99 
from Whittlesey was westward by a large river flowing through 
small Lake Saginaw and into Lake Chicago, which latter still 
emptied through the Illinois river. 
At a still later stage (figure 32) Lake Saginaw merged with the 
waters of the Erie basin to form the large Lake Warren which 
extended along the ice front eastward nearly to central New York. 
As the map clearly shows, the Finger lakes basins of New York 
were then occupied by Warren waters, while Niagara Falls were 
not then in existence because that region was also covered by Lake 
Warren. Lake Warren continued to discharge westward into Lake 
Chicago and the Mississippi river until a very late stage, when the 
waters had worked their way along the border of the Ontario ice 
Fic. 32 Glacial Lake Warren. At this stage the discharge of the lake 
was still westward to Lake Chicago and the Mississippi river, while the east- 
ern end of the lake covered most of the Finger Lakes region of New York. 
Modified from Taylor & Leverett, U. S. G. S. 
lobe into the Mohawk valley which was then occupied by a large 
glacial lake (held up by the Ontario ice lobe on the west and the 
Champlain-Hudson lobe on the east) and thence into the Hud- 
son valley. Thus, for the first time, the Great Lakes drainage 
passed eastward into the Atlantic ocean. This great volume of 
water draining eastward was often in the form of distinct streams 
with the ice front for north wall and the high land of the Helder- 
berg escarpment for wall on the south. Many of these glacial 
stream channels, which are still plainly visible, have been studied 
and mapped by Professor Fairchild. 
4 
