320 
GEOLOGY OF THE FOURTH DISTRICT. 
This condition of the surface clearly indicates the condition of the waters from which this 
deposition was made. On the one hand we have comparatively an evenly distributed deposit, 
as if made by the retiring waters of an ocean ; in another, the long hills, with certain direc¬ 
tions, show a determinate course and more powerful current in the ocean, while the irregular 
conical and dome-shaped hills, with deep, bowl-shaped cavities, show the force of contend¬ 
ing currents, or of other obstructions in the course of the transported materials. 
It becomes very evident, therefore, that to whatever cause we choose to attribute the pheno¬ 
mena of the superficial detritus of the Fourth District, the whole surface has been permanently 
covered by water; for it seems impossible that partial inundations could have produced the 
uniform character and disposition of the materials which we find spread over the surface, not 
only of the limited area we have been describing, but over several hundred miles farther east 
and west. That partial influences have operated, and partial inundations taken place, there 
is no doubt; and some of their effects will be enumerated. Ii is very possible also that many 
of the varying features of this deposit are due to causes not now recognized, and less universal 
than at first view may be supposed. In these I would often be disposed to include the abrupt, 
conical and elongated ridges, which, with no determinate direction, often cover considerable 
spaces, when the surrounding country is comparatively level. 
There is also another fact to be borne in mind, viz. that the materials of the hypogene or 
primary rocks constitute but a comparatively small proportion of the superficial accumula¬ 
tions of Western New-York. The great bulk of the deposit, whether evenly distributed or 
irregularly raised into hills and ridges, is, nevertheless, composed, in large proportion, of the 
rock but a short distance on the north, or perhaps of the one on which it rests, with a con¬ 
stantly decreasing proportion of rocks of northern origin. It is true that boulders of granite 
and gneiss are often scattered in great profusion over the surface, sometimes indeed to the 
almost entire exclusion of every other rock, and they are more or less numerous in almost all 
situations where the superficial detritus has accumulated ; still they rarely enter into the 
great mass so as to constitute any large proportion of the whole. 
Although it may not be impossible that some of these boulders, of granite and other rocks 
of similar nature, have been transported at the period of this great accumulation of local drift, 
and forming a part of the great moving mass; yet they are, for the most part, due to sub¬ 
sequent operations; brought thither by a force which has transported them alone, and which 
has had no great effect, even upon the previously deposited superficial detritus ; and we must 
carefully guard against confounding these accumulations with those of antecedent formation. 
In many instances there has been an intermingling of the products of two periods, and 
sometimes the granite boulders appear to have rolled down from higher elevations, often in¬ 
deed resting upon the most recent superficial deposits.* ] nstances of this kind are visible along 
the valleys of the northern part of the district. On the broad northern slope towards Lake 
Ontario, where hills arc distant, there are numerous and extensive fields of boulders, resting 
upon the surface, or but partially imbedded in the soil, and holding such a position that it is 
* Such as river alluvium, et j. 
