NORTHERN BOULDERS. 
335 
offer any evidences to lead to a belief that glaciers were formed on our northern mountains ; 
that moving down to a sea then covering a large portion of the country, they floated off with 
their loads of earth and boulders, which have been precipitated over the whole of New-York. 
When we examine these boulders, we are naturally led to ask, whether they are of the 
kind of rocks previously familiar to us in place, and if they can be referred to any known 
primary mountains; for if we can once fix their original locality, we are better prepared to 
offer explanations of their mode of transport. A large proportion of the boulders of Western 
New-York are of dark felspathic granite, and red granites like those of the northern part of the 
State. Some of other varieties occur, which are likewise referable to the same region. A 
few of crystalline limestone with serpentine have been found ; and these are so precisely like 
a rock of that kind in St. Lawrence county, that we are inclined to refer to that place as its 
original home. A few boulders of specular iron ore have been found among the most extreme 
southwesterly materials of that kind ; this is precisely like the ore from numerous points in 
St. Lawrence county. These are a few of the analogies which might be enumerated. 
By casting the eye over the Geological map, it will be perceived that the northeastern por¬ 
tion of the State is occupied by a great central nucleus of Primary rocks, consisting of dark 
and reddish felspathic and other granites, crystalline limestones, etc.; this extends, though 
somewhat interruptedly, into Canada. The elevation of a large portion of this country is from 
two to four thousand feet above tide water, and many of the higher peaks approach to the 
elevation of five thousand feet above the level of the sea. 
Admitting that the relative elevations between this part of the State and Western New- 
York have remained the same, the greater portion of the latter may have been submerged 
beneath the ocean, and still there would be large tracts of the former elevated two thousand 
feet above its level. If, under these circumstances, glaciers were formed upon the sides of 
these mountains, and descended to the sea, many of them would be carried forward by the 
oceanic current far into that part of the ocean which then occupied western New-York. Even 
the accumulations of snow and ice during winter, in the streams flowing from these islands, 
would, on the breaking up in spring, carry forward large quantities of loose stones. The same 
is shown by Capt. Bayfield to take place on the breaking up of the lakes and streams of the 
St. Lawrence valley at the present time; and we are warranted in supposing a more severe 
climate under the conditions suggested, as known by comparison in other latitudes. 
From observations in the southern hemisphere, Mr. Darwin has shown that a larger pro¬ 
portional area of water is accompanied (probably as a consequence) by a more equable climate, 
the presence of tropical productions, and at the same time a low limit of perpetual snow, and 
therefore the descent of glaciers into the sea in latitudes as low as 46° 40'.* This reasoning 
he has illustrated by some beautiful comparisons between places in the southern hemisphere 
and different parts of Europe. These facts he has undertaken to apply to the explanation of 
the geological phenomena of the transportation of boulders and fragments of rock included in 
’ Darwin’s Journal, quoted by Mr. Murchison, Silurian Researches, p. 512. 
