Review of History of the Great Lakes. — Spencer. 289 
the water was rising and the other as it was receding, during 
both of which shallow water conditions prevailed. The gravel 
beaches and silt beds, with the intervening zone of dunes and 
sand ridges, complete the testimony that the submergence 
was not only of long duration, but that it was an invasion of 
waters of great extent. Taken alone the silts prove only a 
long duration of time, such as might characterize the depos- 
its of a small lake. But the gravel spits and beaches were 
made by waves, which came in from Georgian bay over the 
basin of Muskoka lake, and these forms prove the wide ex- 
tent of the water. 
It has been held by many that all the abandoned relics of 
submergence found within the St. Lawrence basin are due to 
ice-dammed lakes formed during the glacial recession. But 
the shore lines have now been traced so far northward toward 
the center of the glacial radiant of the Lauren tide plateau 
that this view seems no longer plausible. The inference near- 
est at hand is that the submergence was an invasion of the 
sea and that the Great Lakes were connected with it through 
a strait over lake Nipissing. It is not more than 25 miles 
from the Nelson beach northeast of North Bay to the nearest 
point on the Ottawa river above Mattawa. There is much 
reason to expect that exploration will ultimately prove that 
the upper silts and gravel beaches of the highlands of all the 
upper Great Lakes are of the same age as the higher postglacial 
marine deposits of the lower Ottawa and St. Lawrence valleys. 
A REVIEW OF THE HISTORY OF THE GREAT 
LAKES.* 
By J. W. Spencer . Ph. D., F. G. SS. (L. and A.). 
(Plate VIII.) 
CONTENTS. Page. 
Problems and Progress » 290 
Former High Continental Elevation 290 
Character of the Lake Basins 291 
Glaciation of the Region 292 
Buried Laurentian valley 293 
Buried Tributaries 293 
Reversal ot the Drainage of the Upper Ohio and othei rivers 294 
Closing of the Valleys into Lake Basins 294 
Deserted Beaches in the Lake Region and their Deformation 295 
Warren Water 296 
Algonquin and Lundv Waters 297 
Iroquois Water and Birth of the Modern Lakes 207 
History of the Niagara River and Changes of the Outlets of the l aki 
Recurrent Drainage of the Great Lakes into tin- Mississippi River by 
way of Chicago 300 
*Read in ■fun' Section E <>l' the American Association for the Advance 
ini-ni of Science, a1 the Brooklyn meeting, August 20, 1804. 
