CHARACTERISTICS AND DISTRIBUTION OF LAKES 629 
of about 50 square miles, being 25 miles in length, with a maximum 
width of about 3 miles, and discharges into Lake Champlain. 
"Lake on the Mountain" is situated on the top of a cliff, 
180 feet in height, which rises on the south side of the Bay of Quinte, 
a bay on the northern shore of Lake Ontario. The outflow gives the 
power which operates the Glenora Mills, but its inflow is invisible 
and yet steadily maintained from year to year. The lake is 300 feet 
from the edge of the clifl', and measures three-quarters of a mile in 
length. The greater part of it is shallow, not exceeding a few feet in 
depth ; but close alongside its southern boundary is a great rent, as it 
were, in its bottom, nearly a mile long, one-third of a mile or more 
wide, and varying from 75 to 1 00 feet deep. Probably the rent has 
some connection with a widened fault in the Trenton limestone area 
25 or 30 miles to the north-east of the Bay of Quinte, and the forces 
which gave rise to the fault may have caused subterranean communi- 
cation with higher ground many miles away. The dip of the rocks 
is favourable, and the whole area into the Laurentian region beyond 
is a steady rise, till about 50 miles away a height of nearly 400 feet 
above Lake Ontario is reached. During a period of drought in the 
neighbourhood the level of the lake was well maintained, so that its 
source is not attributable to the rainfall in the immediate vicinity. 
On the other hand, a fair amount of rain fell in the Trenton region 
during that period, so that evidence seems to point in favour of the 
waters having their origin there and reaching the lake by an under- 
ground channel. In August the temperature of the surface water at 
the outlet of Lake Ontario opposite Kingston was about 72° Fahr. 
(22°-2 C), and at the bottom in 78 feet 56^ Fahr. (13°-6 C). At 
the same time in the " Lake on the Mountain the temperature at the 
surface was 74i° Fahr. (23°-5 C), at 80 feet it was 69^ Fahr. 
(20°-8 C), at 45 feet 47° Fahr. (8°-3 C), at 60 feet 43° Fahr. (6°-l C), 
and at 99 feet 42° Fahr. (5° '6 C). In the upper 30 feet, therefore, 
there was little change in the temperature, but between 30 and 45 feet 
there was a rapid fall amounting to 22 i degrees, and from 45 feet to 
the bottom a further fall of only 5 degrees. 
The geography of the region to the north-west of the Laurentian Rivers 
basin, which now drains to Lake Winnipeg and thence through the an?Nelso™ 
Nelson River to Hudson Bay, underwent many revolutions during 
the advance and retreat of the ice-sheet. The drainage to the north 
was obstructed, and a lake formed over the country of mild relief 
surrounding Lake Winnipeg and the Lake of the Woods, and 
extending southward through the Red River valley far into Minnesota. 
This lake, now marked by its ancient shore-lines and the deltas of 
inflowing rivers on the east and west, has been called Lake Agassiz in Lake Agassiz. 
