284 Canadian Record of Science. 
except in one isolated spot, is only 48 feet, and the average 
is only about 30 feet. Whilst thus shallow, the main body 
of the lake east of Pt. Pelée is remarkably level. The 
general depth is between 60 and 84 feet to within four or 
five miles of the shore on each side. 
The deepest point in the lake lies in its eastern third 
about ten miles south-east of Long Point, and registers 210 
feet. Here, parallel with the axis of the lake, there isa 
depression about twenty-seven miles in length by a width 
of from five to six miles, the depth everywhere in which 
exceeds 180 feet. Surrounding this and about forty miles 
long by twenty-five miles wide is an irregular area which 
has a minimum depth of 120 feet. This wider depression 
approaches within six miles of the south shore and thirty- 
five miles of Buffalo, towards which city it gradually shoals 
to 24 feet at the entrance to the Niagara River. The level 
plateau on which the main body of the lake rests is gener- 
ally clay, whilst for the ten miles adjoining the United 
States side, the lake bottom is sand or sand and clay, with, 
occasionally, gravel, and, near the shore, rock. In the 
deeper parts off Long Point, which evidently included a 
wider area in preglacial times, the bottom is clay or mud. 
This is frequently replaced by sand towards the Niagara 
River, whilst near the shore there on both sides the bottom 
is rock. 
The currents of the lake have, in the past, played an im- 
portant part in shaping the contour of the Canadian side. The 
American coast line has a uniformity which the Canadian 
has not. The direction of these currents is seen in the out- 
lines of Point Pelée, Rondeau Harbour and Long Point and 
in the arched contour of the long coast line fronting the 
County of Elgin, whose high clay cliffs have been worn 
gradually backward through great distances to their pre- 
sent position by the eroding action of waves, frosts and 
rains, and have supplied material for shallowing the lake 
in front and building up Long Point. This process is still 
going on. Within the barriers created by Point Pelée, 
Rondeau Harbour and Long Point it is, however, being 
