Researches relating to the Great Lakes. — Spencer. 1 1 5 
beaches in both places were found to record the evidences 
of gentle terrestrial movements. Following up his investi- 
gations, Prof. Gilbert connected the various fragments of a 
great beach upon the southern and eastern sides of lake 
Ontario, as far as Adams Centre, near Watertown, N. Y.,^'^' 
and found that the old waterline was deformed to the extent 
of several hundred feet in proceeding northeastward. This 
was an admirable piece of work, whicli was invaluable to the 
writer, who extended the observations farther! and made use 
of them in measuring the amount of the long sought for ter- 
restrial deformation at the outlet of lake Ontario, and found 
that these post-glacial movements were sufficient to account 
for the rocky barrier across the Laurentian valley, producing 
the basin which retains the waters of lake Ontario. The 
channels across this rocky barrier, however, were closed with 
drift deposits reaching to a depth of 240 feet. In thus estab- 
lishing the ancient drainage of the Ontario basin, after years 
of observation, often representing but little progress, the 
phenomena of the basin were discovered without the glacial 
theory of erosion. Then the writer found that the drowned 
channels cross lake Huron, and passing through Georgian 
bay, continued beneath hundreds of feet of drift, eastward of 
the Niagara escarpment, and joined the Ontario valley a few 
miles east of Toronto. A similar channel (the Huronianj 
crossed the state of Michigan, passed through Saginaw bay, 
and over the sub-lacustrine escarpment, to the deeper chan- 
nel of the Huron basin. J The Erie (Erigan river) drainage 
had been found to pass into the head of the Ontario basin. 
Thus was discovered the course of the ancient Laurentian 
river and its tributaries of antiquity. These upper basins were 
also affected by the terrestrial tilting recorded in the beaches, 
as well as by the drift obstructing them. 
Prof. Gilbert, who had, many years before, mapped 
beaches at the head of lake Erie§ afterwards measured the 
* Report of the meeting of the Am. Assc. Adv. Sci., Science, Sept.. 
1885, p. 222. 
tThe Iroquois Beach: a Chapter in the Geological History of Lake 
Ontario, by J. W. Spencer. Trans. Roy. Soc. Can., 1889, pp. 121-134. 
(First read before Phil. Soc, Wash., March, 1888.) 
J Origin of the Basins of the Great Lakes. O, J. G. S. (Lon.), vol. 
XLVI, 1890, pp. 523-533- 
§'See Geology of Ohio, vol. II, 1874. 
