Glacial Geology ni America. — Fairchild. 185 
blocking also of the low divide between the Ontario basin and 
Mohawk valley, which is far below the old shorelines. In 
the same year, 1872, Winchell suggested that the waters of the 
Winnipeg basin (lake Agassiz) had been forced south, through 
river Warren, by a glacier barrier. These were probably the 
earliest definite localization of glacial waters. 
The first mapping of ancient beaches, and the correlation 
of those beaches with an abandoned outlet, was by Mr. Gil- 
bert, in 1871, in description of the Maumee valley beaches and 
the Fort Wayne outlet. Land deformation he supposed was 
the cause of the change in water level. 
The tracing of the beaches in the Erie basin was done by 
Gilbert, Winchell, Klippert and Newberry mostly before 1872. 
Newberry's map of the beaches west of Cleveland, 1874, is the 
first map of glacial lake beaches, so recognized. 
The earliest systematic work upon the beaches in the On- 
tario basin was done by J. W. Spencer and published in 1882 
with a theory of marine origin. In 1885 Mr. Gilbert printed a 
description of the high beaches upon the southern side of the 
Ontario basin and correlated them with an eastward outlet 
by the Mohawk-Hudson. The names W^arren, Algonquin and 
Iroquois were applied by Spencer to the ancient high waters 
of the Erie-Huron and the Ontario basins in 1888, but with de- 
nial of their glacial character. 
The earliest comprehensive account of the glacial lake his- 
tory of the Laurentian basin was published by Gilbert in 1890, 
with maps, which were the earliest cartographic representa- 
tion of glacial lakes. In this admirable paper he showed the 
rise of the beaches northeastward, due to the dilTerential uplift 
of the region; the fluctuation of level in the basins produced 
by the opening of successively lower outlets toward the north 
and the progressive tilting of the land throwing back the flow 
upon southern outlets; with the final result in the present great 
lakes. 
For the full confirmation of the theory of glacial dams it 
was necessary to prove the actual relation of moraines, as 
marking locations of the ice barrier, to the beaches. This 
was first done by Frank Leverett in 1892, in the western sec- 
tion of the Erie basin; and in 1895 in the southeastern section. 
In 1896 F. B. Taylor correlated the beaches and moraines in 
