LAKE ALGONQUIN. 
3 
In 1908, an instrumental survey of the shore-lines of the 
extinct lakes Algonquin and Nipissing in southwestern Ontario 
was undertaken by Mr. J. W. Goldthwait under the direction of 
Mr. F. B. Taylor, the results of which were published as Memoir 
No. 10 of the Geological Survey, Canada. The Lake Simcoe 
district, Ontario, was included in the area examined by Taylor 
and Goldthwait and altitudes of the Algonquin shore-line were 
determined at a number of localities in the district. An isobasic 
map of the Algonquin beach and a profile of the warped Algon- 
quin water-plane accompany the report. The map and profile 
show the direction and rate of tilt of the beach and the rapid 
steepening of tilt in the northern portion of the Lake Simcoe 
district. Goldthwait showed “that the strong Algonquin beach 
was formed during the activity of the Algonquin river as an 
outlet/' His observations around Balsam and Cameron lakes 
also showed “that even in these small basins there is a distinct 
shore line which is either the extension of the Algonquin beach 
itself, or its contemporary in a chain of pools along the Algonquin 
river. A comparison of the five or six measurements in this 
district shows that if this shore line is the Algonquin it has suf- 
fered local warping of an unusual sort. Nowhere else in the 
Great Lake region where detailed work has been done, has a clear 
case of local warping of the Algonquin beach been discovered. 
The alternative is that this shore line on Balsam and Cameron 
lakes marks the outline of a chain of lakes between rapids on the 
ancient outlet ; that in Balsam lake the water plane was originally 
lower than in Lake Algonquin, and in Cameron lake it was still 
lower." 1 
Lake Simcoe district, Ontario, is one of the most favourable 
localities in the Great Lakes region for a study of the character 
of the differential uplifts which are known to have taken place 
by the deformation of the Algonquin beach; for this beach is 
well developed in the district and can be followed continuously 
for long distances. It occurs on both sides of Lake Simcoe and 
its general trend on both sides is approximately in the direction 
of maximum uplift so that isobases or lines of equal deformation 
can readily be drawn and a profile constructed showing the 
i Goldthwait, J. W., Geol. Surv., Can., Mem. 10, 1910, pp. 46-47. 
