20 
GEOLOGY OF THE SECOND DISTRICT. 
interior of the wilderness. Many of the observations in the report for 1840 were highly in¬ 
teresting and important. In estimating the labor required for the establishment of doctrines 
or principles in geology, or any of the classificatory sciences, only a small amount of that 
which has been required for those ends can appear connected with the result, unless the de¬ 
tails are given in the form of a journal; the reason of this is, that it frequently requires as 
much labor to establish a negative as a positive result; all of which, as it concerns the former, 
must necessarily go for little or nothing; it is only the latter which goes upon the record. 
The non-existence of gold in primary limestone, required as much labor, and a series of ob¬ 
servations as complete and full, as those which have determined its position in the talcose 
slate. Such has been the case in the prosecution of many inquiries relating to the geology 
of the State ; and were details given in full in many instances, it might appear, to some, that 
time had been wasted in an unprofitable pursuit; while, in reality, the subjects in question 
would have been left in an uncertain state, if left unprosecuted to the extent to which they 
have actually been carried. 
With these general remarks and statements of what was known of the geology of the 
Northern District, at the commencement of the survey, I shall proceed with that part of my 
report which is usually termed Scientific Geology, or that division of the science under which 
the masses composing the accessible portions of the earth are classed and described in a 
language more or less technical, and their relative positions assigned them according to prin¬ 
ciples which have been established by observation. 
Technical descriptions, however, will only be given where clearness and precision require 
them, or where popular descriptions would be likely to lead to error and misapprehension ; 
and conceiving that the report is intended to benefit general readers, or those who have not 
made geology a particular study, such a course seems to be called for. We are relieved, how¬ 
ever, from much embarrassment of this nature, in consequence of there being, comparatively, 
but few scientific or technical terms in this department of knowledge. The method which I 
shall follow in describing the rocks of the Northern District, will be that of the ascending 
order; an order which has usually been adopted in this country, and one which appears to be 
best adapted to impart distinct and accurate views of the chronology of events which have 
been connected with the early history of the eartli. Whatever may be the best method in a 
general treatise on rocks, there can be but little doubt that this which I propose is best 
suited to the geology of the district, and which will enable me to give a clearer account of the 
subjects I have been called upon to investigate. 
In order that the views of the geology of the Northern District may be simplified, we may 
consider the rocks as belonging to two classes : the crystalline, or primary in the Wernerian 
sense of the word ; and the sedimentary, or those which have been deposited from water. The 
former occupy the more central parts of the district; they rise into high and precipitous 
mountains ; while the latter occupy a belt, which borders the preceding on all sides, and from 
which they usually decline. This belt is, however, imperfect, if we confine our observations 
solely to New-York. Thus, at several points upon the eastern side, the primitive ranges, 
when they extend to Lake Champlain, break through it; in many places it is quite narrow, 
