100 Mr. Maclure on the Geology of part of N. America. 
Island, would not have been accumulated at this ies. and 
the current now called the Gulf Stream, would have then 
most probably run along the foot of the chain of esveaethte. 
he continent east of the Stoney Mountains, and south o 
the north edge of the great lake, would then consist of an 
immense lake, surrrounded on the east and south side by a 
strip of high land from one hundred to two hundred miles 
broad; the rain falling upon which would partly fall into the 
Jake and partly into the ocean, through small rivers, along 
the mouths of which navigators might have in vain searched 
for rivers proportionate to the apparent extent of the conti- 
nent, as they now do on the coast of New ito Wales, for 
rivers capable of draining so extensive a country. 
he passage of the St. Lawrence through the high ridge 
between Quebec and Montreal, must either have been torn 
asunder by an extraordinary convulsion, been always in that 
state, or it must have been worn down by the gradual butcon- 
tinued action of running water, aided by the friction of all the 
substances it carries along with it; the undisturbed bevel 
of all the surrounding strata both on a banks of the St. 
rence and Hudson, renders the first supposition idea. 
ble ; on the second supposition that the river had always 
run freely through the passage in those mountains, it must 
follow that the river had always run in its bed from Lake 
Ontario to Montreal, and from the roy of water and ra- 
pidity of its current, for so long a time, must have worn 
down a deep channel, and buried itgelf between high and 
perpendicular banks ; but this does not correspond with the 
actual state of the river, which from the lake to the rising 
ground above Montreal runs in a bed very little below the 
Jevel of the surrounding country, nor does either the present 
situation of the river or its banks, warrant the supposition 
that the action of the current had continued so long: by 
the same supposition the level of Lake Ontario must have 
always remained as far below the level of Lake Erie as at 
present, and the waters must have constantly fallen over a 
ridge at Niagara; but the small progress it has ma 
wearing away that ridge, compared with the effects of otbet 
rivers, (for instance, the Rhine below the lake of Constance 
with a tenth part of the water has worn a dee eper bed ten 
times the distance through the high lands composed of hard- 
er materials) is against the probability of such a supposition; 
