GEOLOGY AT THE COMMENCEMENT OF THE SURVEY. 
19 
of the geology of the Northern District. Mr. Eaton, who was the oldest laborer in geology in 
New-York, had not extended his observations far into this field. He had, however, represent¬ 
ed the Me Combe Mountains as composed of ranges of gneiss, extending from the valley of 
the Mohawk to the Provincial line, and the intermediate valleys, of limestone extending along 
their bases and around their northern extremities ; and the whole section as being composed 
of two principal formations, a carboniferous slate, denominated primary, and a calcareous for¬ 
mation, denominated secondary. 
It is sufficiently evident that all this was imaginary ; it is even difficult to conceive how 
imagination could have carried even a partial observer so far from the truth. 
In the 19th volume of Silliman’s Journal, a paper on the geology and mineralogy of the 
county of St. Lawrence was published by Mr. Finch. In this paper there is a brief account 
of the rocks of this county; the Potsdam sandstone was spoken of as a transition rock, and 
the calciferous sand-rock of Eaton as a siliceous limestone ; but their geological position does 
not appear to have been known to the author. A very good account of the minerals is given 
in that paper. In addition to this, however, several gentlemen, previous to Mr. Finch, had 
explored this field mineralogically with success ; among whom were Dr. Crawe of Water- 
town, and Dr. Murdock of Gouverneur. Much more, therefore, had been accomplished in mine¬ 
ralogy than geology. Other regions which had also been explored, were those of Lake George 
and the vicinity of Willsborough ; and many of the minerals of those primary rocks were 
already well known to the public. The beautiful labradorite too had been discovered by Mr. 
Henderson, near the site of the Adirondack iron works. 
But as it regards the geology of the Second District, nothing had been really settled or ac¬ 
complished. Gneiss, granite, limestone, sandstone and iron, it is true, were known to exist in 
this section; but their relations, their extent, their value as mining rocks, and various other 
facts and inquiries remained unknown. The field was therefore new, and I was obliged to 
commence my observations without a guide or a starting point. To those who may now 
commence the study of the rocks of this region, it may appear perfectly simple; and it may 
be that only a few days, or weeks at most, will be required to obtain possession of the general 
arrangement and relations and characters of the rocks. The determination of these points, 
however, has required a multitude of observations both within the district and out of it, in 
order to establish those facts beyond a doubt, far greater probably than one would suppose, 
.who is unacquainted with the nature of those inqiuries. 
As it regards the topography and general features of this portion of the State, I may also 
justly remark that they were subjects as little known as the geology. The mountains were 
estimated, or rather given in the various works of the day,, as varying in height from 500 to 
2000 feet. Those statements may be compared with the actual results which have been ob¬ 
tained by baropietrical measurements, the correctness of which have been verified in several 
instances by levelling, in surveying for' the northern railroad route, by competent engineers. 
In obtaining some of the heights of elevated points in this region, I have been assisted by Mr. 
Redfield of New-York city, and Prof. F. Benedict of the University of Vermont. The latter 
gentleman, at my request, devoted considerable time to the prosecution of this object, in the 
