Lake Warren* is the name given by geologists to an extensive body of water held at a high level in a portion of the Laurentian basin by a barrier of glacial ice which blocked the low eastern outlets. The Laurentide continental glacier, which at its maximum covered all the upper Mississippi valley and the basin of the Great Lakes, had at this time receded so as to leave at least the southernmost part of the Laurentian basin exposed. The ice still lay over most of Canada and northeastern New York, and the water in the uncovered part of the basin being unable to escape by the Saint Lawrence or Mohawk valleys, these being still closed by the ice-sheet, was compelled to find an outlet to the sea by the Mississippi.
The glacial lake Warren is believed to have covered all of the basin of the present lake Erie, at . . .