330 
GEOLOGY OF THE FOURTH DISTRICT. 
surfaces of these, from the highest to the lowest, are grooved and striated, and in the lime¬ 
stones often beautifully polished. 
In the first place, we are unacquainted with any high land on the north, from which glaciers 
could originate to cover this entire surface. The relative levels, as well as the directions of 
the water courses, must also have been different, to have allowed of such effects from glaciers ; 
for under present circumstances, we should hardly expect to find a glacier advancing from 
the valley of Lake Ontario, toward the southern margin of the State, and ascending nearly 
two thousand feet in one hundred miles. Even admitting the theory to be true, it is probable 
that the glaciers would originate among the mountains of Canada, or farther north among the 
primary rocks ; and in this event, we might expect to meet intermingled with the earliest drift a 
considerable proportion of granite, and other pebbles and boulders of the older rocks, which is 
not the case. There is also another circumstance connected with glacial action, which deserves 
inquiry. The deep valleys were either excavated previously ; at that period ; or subsequently. 
If these were excavated previously, then the power which accomplished it was sufficient to 
produce all the striae and grooves which we now find. It can hardly be supposed that these 
excavations were made at the time the glaciers were progressing southward; for no such 
power is attributed to them, and they usually follow the course of valleys previously formed. 
If we attribute these valleys to subsequent causes, then we have a power capable of obliterating 
all traces of glacial action. 
Not being familiar with the views of M. Agassiz from his own writings, I may have an 
imperfect or erroneous opinion of his theory ; but so far as I understand it, it seems inadequate 
to produce all the phenomena in question, and inapplicable to this portion of the country. 
In regard to glacio-aqueous action, there are other considerations to be taken into view. 
Glaciers, loaded with fragments of rock, may have drifted from the base of mountains, and 
in passing over shallow portions of the ocean, have scored the surfaces of the strata ; but in 
order to accomplish this, a peculiar condition of things is necessary. It requires that the 
surface be free from the accumulation of detritus, which in the ocean cannot be, except the 
elevated rocks; and we can never find any portion of country which has been for a con¬ 
siderable time submerged beneath the ocean, but is covered to a greater or less depth with 
superficial detritus. Again, it requires that the surface should be even; or that there should 
be an immense number of these bergs at all conceivable depths, to touch the varying elevation 
of the strata. And even under the most favorable circumstances, it requires that thousands 
and millions should have traversed the ocean, and stranded upon the bottom, in order to pro¬ 
duce the wearing down, the polishing, and the myriads of small and large grooves and striae 
which mark the surface of strata. 
It is not pretended that more than a few masses of granite or other rocks can be attached 
to the bottom of an ice island, and therefore but few points could touch the bottom at one time; 
and if we reflect that they may often be as irregular and jagged in their outline beneath the 
surface as they are above it, then the points will be few indeed. If an ice island were to 
be stranded in the valley of Lake Ontario, supposing the whole country covered with water, 
it woidd require to be elevated three hundred feet to groove the Niagara limestone, and one 
