262 Canadian Record of Science. 
ward, and those on the Manitoulin Islands in the curve 
which the outcrop of the Niagara limestones there takes, 
slope to the southward. 
The Georgian Bay in this part appears to be subsiding, 
according to Bolton’s survey. North-Hast Shingle, off 
Lonely Island, presently 2 to 5 feet below water, was in 
Bayfield’s time, 3 to 4 feet above, whilst White Shingle, off 
Snake Island, now 1 foot below, was formerly 2 to 3 feet 
above. As Bayfield’s survey was made in 1822, the max- 
imum subsidence has been about one foot in each nine 
years. Commander Bolton, however, has personally sug- 
gested to me the possibility that floating ice may have been 
the cause. 
On the eastern banks of the St. Clair River there are also 
evidences of subsidence, but these may be local. 
It is possible that in some sections the Niagara escarp- 
ment, including under this term the whole strata exposed, . 
may result partly from a fault. The country at the foot of 
and approaching the escarpment is in Canada, almost in- 
variably either obscured by heavy superficial deposits, or 
covered by the waters of the lake, rendering exact observa- 
tion difficult. It is quite possible that could the profound 
depths of the lake adjoining the east and north side of the 
Bruce Peninsula be studied, such a fault or faults might be 
discovered. Whilst the escarpment at Cabot’s Head towers 
324 feet above the water, the depths close at hand in the 
Georgian Bay reach about 498 feet, giving a total of 822 feet, 
and along the face of the escarpment lie the deepest parts 
of the Georgian Bay. From this line of depression the 
slope is upward towards the north-eastern shores of the bay, 
where the depths outside of the islands average about 60 
feet, excepting in Parry Sound, where there is a maximum 
of 354 feet. 
From Cabot’s Head south-eastward, at every point and 
island, and sometimes also in the bays, Mr. Alex. Murray 
found a fringe of reefs close to the cliffs, all apparently com- 
posed of loose blocks, and probably all derived from the 
destruction of the cliffs by rapid. currents, by the action of 
