1898-99. | THE GEOLOGICAL HISTORY OF LAKE SUPERIOR, 57 
those of marine species when embedded in sand or gravel. It is, 
therefore, probable that at the close of the glacial epoch, an enormous 
sheet of fresh water covered the whole region of the great lakes of the 
St. Lawrence and extended far to the south, and that it was drained 
away to the southward by a slightly greater elevation of the land in the 
north. Geologists have named this vanished sea Lake Warren. 
After a time, the land to the south of the general basin of the great 
lakes had become dry, but all the water above Lake Ontario was united 
in one body, which included Lake Nipigon and flooded the land north 
of Georgian Bay as faras Lake Temiscaming. Dr. Spencer has named 
it Lake Algonquin and it discharged by the Trent valley into his Lake 
Iroquois which covered the site of Lake Ontario and the surrounding 
country and flowed out to the sea by the Mohawk valley. 
When the water had fallen to within about 100 feet of the present 
level of Lake Superior, it remained united with Lakes Michigan and 
Huron as one sheet in three lobes discharging by way of Lake Nipissing 
and the Ottawa River. Mr. F. B. Taylor proposes the name Great Lake 
Nipissing for this former inland sea. The fact that a differential eleva- 
tion of the land towards the north-northeast has been going on and is 
still in progress is proved by the undoubted southward inclination of the 
ancient beaches around the great lakes which succeed one another and 
together record a movement which was continuous through a great 
length of time, and also by other phenomena which I have observed in 
the northern part of the Province of Quebec and in the Labrador 
peninsula. But we are not dependent on the geological records alone to 
establish the existence of this movement in the crust of this part of the 
earth. Professor Gilbert has carefully investigated the readings of 
various gauges which were placed many years ago at different points on 
the American side of the lakes and he has found that, after eliminating 
all disturbing elements, they agree in showing a steady fall in the water 
towards the north and a corresponding rise towards the south, which 
amounts to about .42 of a foot per 100 miles per century. Iam of the 
opinion that both the amount and rate of the uplift increase for a certain 
distance to the northward or until we reach the centre of the maximum 
height of the ice during the glacial period ; and consequently around 
Hudson’s Bay and in the Labrador peninsula the elevation is going on 
more rapidly than in our lake region. This is only what we might 
naturally expect if our theory of the cause be correct. 
As a consequence of this tipping up, or canting of the lakes, their 
northern shores are shoaling, while their southern ones are flooding. 
