LAKE ALGONQUIN. 
21 
been generally supposed. Correlative shore-lines of the highest 
Algonquin shore-line occur in several basins along the Trent 
valley. Strongly marked outlet channels show that the ancient 
water bodies in these basins were connected with each other and 
with the Balsam Lake embayment of Lake Algonquin. The 
main channel of the ancient Algonquin river between Stony 
Lake and Rice Lake basins was by way of the Indian River 
valley. At the mouth of this valley in Rice Lake basin a large 
delta occurs. This delta was deposited in Lake Iroquois and 
was formed by the Algonquin river during an early stage of 
Lake Algonquin when the discharge was largely by way of the 
Trent valley. The Otonabee outlet channel and Peterborough 
delta are correlated with the “two outlet” stage of Lake Algon- 
quin when the discharge was divided between the Trent valley 
and St. Clair outlet. They are probably post-Iroquois in age. 
The strong outlet channel along Trent valley below Rice lake is 
correlated with the Otonabee Valley channel. Its exact relation 
to the post-Iroquois water bodies in the Ontario basin is not 
known. 
The total fall in the Algonquin river from Lake Algonquin 
to Lake Iroquois probably did not exceed ISO feet. This is 
about 100 feet less than the difference in altitude of the two lakes 
as determined from a comparison of the altitudes of the Algon- 
quin and Iroquois beaches in the southern part of the Huron and 
southwestern part of the Ontario basins respectively. This 
seems to show as Gilbert and Taylor concluded that, previous to 
the Algonquin uplift, and during the early stage of Lake Algon- 
quin, when the discharge was largely by way of the Trent valley, 
the plane of Lake Algonquin was much lower in the southern 
part of the Huron basin than it was at the later “two-outlet” 
stage of the lake when the discharge was divided between the 
Trent outlet and the St. Clair outlet. 
An isobasic map of the Algonquin beach and a profile of 
the warped Algonquin water-plane in Lake Simcoe-Balsam 
Lake district show that there are remarkable changes and 
irregularities in the direction and rate of uplift. The profile 
of the warped Algonquin water-plane along the line of maximum 
uplift seems to show that the character of the deformation is 
