184 The American Geologist. September, i898 
questioned, but the facts are so numerous, so easily found and 
verified and so clear and incontrovertible that doubt is no 
longer possible. 
With the approximate determination of the trend of the 
retreating ice foot, as shown by the peripheral drift, the history 
of the glacial waters becomes possible. The study of glacial 
lakes naturally followed the study of moraines. The two 
studies are now prosecuted together with advantage, since it 
is found that shorelines and outlet channels must frequently 
correlate with moraines. 
The conspicuous shoreline phenomena about the Lauren- 
tian great lakes were early observed by settlers and travellers, 
particularly in the basins of Ontario and Erie, and their char- 
acter as beaches was understood. Lyell in 1842 regarded 
them as marine, but the common explanation and the correct 
one, attributed them to fresh waters. They were the subject 
of study and printed description by Thomas Roy (1837), 
Lyell, Hall, Whittlesey, Newberry, Gilbert, N. H. Winchell 
and Klippert before the true cause of the high waters was 
understood. Dr. Newberry seems to have been the first one 
to recognize the ice barrier as the occasion of the high-level 
waters in the Laurentian basin. As early as 1862 he clearly de- 
scribed the ice wall of the retreating glacier as forming the 
northern shore of the fresh-water inland sea and described the 
consequent phenomena. In 1869 he presented the same facts 
more definitely and with greater fullness, but apparently he 
did not yet clearly realize that the ice wall was the dam or bar- 
rier which retained the broad waters at the ancient high level, 
suggesting, instead, some change in the attitude of the land. 
However, he did recognize the ice barrier in his first vol- 
ume on the geology of Ohio, published in 1873; and in the 
second volume, 1874, he not only clearly predicated the ice 
dam but discussed the whole history of the glacial waters, 
from the early primitive stages, in a manner that shows he had 
a clear conception of the main facts. 
Before this association in 1872^, N. H. Winchell suggested 
the damming of the Michigan waters upon the north as having 
made the ancient Chicago outlet effective; also the blockade 
of the St. Lawrence valley as causing the high-level waters in 
the Erie basin. The latter suggestion doubtless implied the 
