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 McCoMBE 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 publi-shed by Mr. Finch. In this paper there is a brief account 

 of the rocks of this coiuity ; 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, iiad 

 explored this field mineralogically with success ; among wlu)m were Dr. Crawe of Water- 

 town, and Dr. Murdock of Gouvemeur. Much more, therefore, had been accomplished in mine- 

 ralog}'than geoloay. 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 knowoi 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 botli within the district and out of it, in 

 order to establish those facts beyond a doubt, far gi-eater probably than one would suppose, 

 who is unacquainted with the nature of those inquiries. 



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 comjaared with the actual results which have been ob- 

 tained by barometrical 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 lime to the prosecution of this object, in the 



