THE QUATERNARY PERIOD 



345 



sey 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 (Fig. 217) 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 



1/ ( A 









Fig. 217 

 Glacial Lake Warren. At this stage the discharge of the lake was still west- 

 ward to Lake Chicago, while the eastern end of the lake covered most of 

 the Finger Lakes region of New York. (Modified by W. J. M., after Taylor 

 and Leverett.) 



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 lobe into the Mohawk Valley of New York, 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 then into the Hudson 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 



