364 
GEOLOGY OF THE SECOND DISTRICT. 
undoubtedly continuous ; but at the present time, we find it only in separated beds : frequently 
the inferior beds remain, but more generally the upper are entirely removed. 
Superficial Covering, Drift, or Boulder System of St. Lawrence. 
The Boulder system or drift of this county differs in no respect from that of Franklin. It 
is, however, more favorably located for observation, as St. Lawrence has a larger territory 
than Franklin, and lies in a direction well formed to receive the floating materials from the 
north. The country slopes generally to the St. Lawrence river, in no part of the county steeply, 
but in by far the greater part very gradually. 
The towns on the river, those which are underlaid by the calciferous sandrock, are low. 
Passing east from this to the sandstone of Potsdam, we ascend as it were from a lower ter¬ 
race to a higher; and in going still farther east, from the potsdam sandstone to the primary, 
we reach a higher terrace still, and a portion of the county which is thrown more into hills 
and ridges ; but still even in this part, for a wide space, there are but few steep and abrupt 
eminences. Upon all these terraces we find a thick mantle of sand, gravel and boulders, all 
of which belong to one era, or one system : it is the Drift or Boulder system. Now although 
the river towns are lower and more level, still they do not present a greater accumulation of 
these loose materials than the higher towns, and perhaps even not so great. This is contrary 
to what we should expect. The materials in the former or lower district, however, are all 
finer; that is, there is more sand and gravel, and it is spread more evenly over the surface. 
But there is a difference in another respect: there is more clay, which is frequently laid bare ; 
and the loose materials, instead of having accumulated, have been apparently removed. Upon 
the sandstone region, the drift begins to accumulate, and we now find quite thick and heavy 
beds, and coarser too than in the limestone district. At the next step east, which brings us on to 
the primary, we begin to meet with large boulders imbedded in coarse gravel and sand. These 
beds lie in steep hills or ridges. In this arrangement, we find that it forms no exception to other 
parts of the district; for without exception, I believe, the coarse heavy materials have been trans¬ 
ported to the higher levels, where they form stony rough ridges. The kind of boulders which 
prevail are those of granite and sandstone ; the former arc the transported rocks, and the latter 
appear to have been broken from the rock below. They are less rounded than the granite. 
In the primary class we find also a few large boulders of hypersthene rock, particularly in 
the neighborhood of Ogdensburgh: generally they are not carried so far from the river as those 
of granite. These boulders may be traced northwards ; they do not, therefore, appear to have 
been derived from the hypersthene rock of Essex ; for we do not find that they increase in 
that direction, but rather diminish. We, however, find them continuously in a line parallel 
with the river : it appears, therefore, that they came from that direction. 
Comparing the northeast part of the county with the southwest, another difference is found 
to prevail. In the towns in the former direction, a great many boulders of limestone are 
found, some 6f which belong to the rock of the county: they are of the calciferous, but 
