58 NEW YORK STATE MUSEUM 



Though of a temporary nature, these bodies of water endured suffi.- 

 ciently long to permit the formation of well marked beaches with 

 their accompaniment of bars, sand-spits and other wave-formed 

 features. These have been carefully studied and mapped by a num- 

 ber of observers, and the general extent and outline of these lakes 

 is today pretty accurately determined. 



The largest of these glacial lakes, though not the first to come 

 into existence, was glacial Lake Warren. ''At its maximum extent 

 Lake Warren covered the south half of Lake Huron, including 

 Saginaw bay, the whole of Lake Erie and the low ground between 

 it and Lake Huron; extended eastward to within twenty or thirty 

 miles of Syracuse, N. Y. and probably covered some of the western 

 end of Lake Ontario." ^ The retaining ice wall on the east ex- 

 tended in a northwesterly direction, across western New York, 

 Lake Ontario^ and the northeastern end of Lake Huron. This 

 position of the ice front is in part inferred from the existence of 

 moraines of sand and gravel along a portion of that line. The 

 total area of this ancient lake has been variously estimated as in- 

 cluding from one hundred thousand to two hundred thousand 

 square miles of surface but this estimate is based on the assump- 

 tion that the lake occupied the greater part of the area of the 

 present upper Great lakes, with the intervening land, a supposition 

 which Taylor holds to be incorrect. The area of Lake Warren 

 was probably less than 50,000 square miles, or approximately half 

 that of the state of Kansas. The extent and level of this lake was 

 not constant, there being many oscillations, due chiefly to warpings 

 of the land surface. These oscillations are recorded in the various 

 beaches which have remained to the present time. The chief outlet 

 of Lake Warren was by way of the Grand river valley into the 

 valley of Lake Michigan, the southern end of which was then much 

 expanded and occupied by the waters of " Lake Chicago." The 

 outflow of this lake was to the Mississippi by way of the Illinois 

 river, across the divide near where Chicago now stands, thus tem- 

 porarily reestablishing the southward drainage of this region. 



'Taylor. A short history of the Great lakes, p. loi. 



