LAKE RIDGES. 
353 
St. Lawrence and Hudson. These may have been successive stages in the subsidence of the 
waters, under the condition supposed, during which the northern mountains formed groups of 
islands, from which masses of ice with boulders were drifted over the surrounding sea, and 
deposited at various elevations. This supposition seems not improbable, nor would it be 
surprising if some of the remains of shells found in the ridge of Lake Ontario should prove 
to be marine, thus in a measure identifying it with the period of the tertiary of the St. 
Lawrence and Champlain valleys. 
Tire elevations of the different levels of this former ocean may, hereafter, prove of the 
highest interest, in connection with the theory of the distribution of boulders. The fields of 
boulders between Lake Ontario and the ridge were evidently dropped upon its bed in the 
most quiet manner. The thin deposit of older drift appears not to have been disturbed, and 
it lies evenly spread over the strata, till we approach the ancient shore, where the waves 
had sufficient power to pile up all the loose materials in one long ridge. 
From the fact that no other well defined ridge exists between this one and the present lake, 
it seems that the elevation of the land was rapid; for, had there been a cessation for any con¬ 
siderable time, the waves would have thrown up another ridge of the kind, which does not 
appear in New-York. 
The existence of these ridges, and others at higher elevations, though less prominetly de¬ 
fined, give us sufficient proof of the existence of water at different elevations, and of its 
gradual subsidence. These evidences have given origin to the theory of an ancient inland sea, 
which formerly spread over a large portion of the territory east of the Rocky mountains, and 
was limited by the great primary regions of New-England on the east. Subsequently, and 
at successive periods, this sea reduced its barriers, and eventually discharged itself by the 
valleys of the St. Lawrence, the Hudson and the Susquehannah, draining an immense area. 
This view seems very plausible, and there are numerous facts to sustain the conclusion, but 
still there are objections which appear to me insurmountable. 
The evidences of the former elevation of the inland waters remain, principally, in the 
ridges and terraces of superficial materials. These are accumulated in valleys, and upon 
their sides, showing them to be of subsequent origin to the formation of the river channels 
and lake basins. All the great outlets being apparently of the the same date as the valleys 
alluded to, it follows that this inland sea, if existing at all, had only to excavate its outlets 
through the superficial detritus. From all the testimony in the case, it appears more pro¬ 
bable that these marks of the ancient limits, which are everywhere visible, resulted from the 
partial submergence of our continent after the present character of surface had been im¬ 
pressed upon it, or from the action of water during its later elevation. These ridges are the 
lines of successive emergence, and they are more or less strongly marked as they remained 
for a longer or shorter time the limit of the water. 
Mr. Roy, civil engineer at Toronto, Canada, has examined these ancient sea beaches with 
much care; and has thus been able to establish several lines, at successive elevations, be¬ 
tween the level of Lake Ontario and the height of 1000 feet above the ocean. From these 
[Geol. 4th Dist.] 45 
