:i08 GEOLOGY OF THE SECOND DISTRICT. 



is readily reduced to a state fit for smelting. It is mixed with hornblende, and a small quan- 

 tity of a reddish mineral which has some resemblance to phosphate of lime. Still, we observe 

 none of the effects of this substance in the iron. This ore makes a tough iron, suitable for 

 chains, horseshoes and nails, hoops, etc., and all those purposes where a hard tough iron is 

 required. Some portions of the vein furnish an ore resembling the grey ore of the Arnold 

 vein, but the iron is like that obtained from the Cook ore. 



Sailly and Averil's vein. This ore breaks into angular fragments or masses. It is fine 

 grained, and intermixed with greenish matter which appears to be pyroxene. It contains 

 some sulphuret of iron, and the ore is brighter than that of the vein just described. It con- 

 tains about one-third of its weight of earthy matter. Its matrix is also a red coarse granite, 

 in which large crystals or masses of feldspar are quite common. From the general character 

 of the ore and rock, it seems to be a continuation of the preceding vein. 



These veins are favorably situated for the manufacture of iron, being only about three miles 

 north of the Saranac, where there is abundance of water power, and in the midst of a country 

 abounding in wood. , 



LOWER MEMBERS OF THE NEW-YORK SYSTEM. 



The great development of the lower members of the New-York system, is the most dis- 

 tinctive characteristic in the geology of Clinton county. The series extends from the Pots- 

 dam sandstone, to the Utica slate. Between these extremes, several thick masses occur, which 

 do not appear in other parts of this district. It will be my object to give a full view of the 

 rocks, as they are here developed. The most important and interesting fact is the addition 

 of beds to most of the rocks, which rarely, if ever, appear in other places where the same 

 rock seems to be fully formed. For example, the calciferous has many additional beds, some 

 of which might be separated from it and placed among the rocks ; the birdseye contains many 

 feet of a drab-colored rock, quite distinct in mineralogical characters from the birdseye itself; 

 and the chazy limestone, too, is a much thicker rock here than elsewhere. But leaving these 

 peculiarities to be more distinctly noticed in another place, I will proceed in the usual order, 

 and describe first the potsdam sandstone. 



This rock, where it enters Clinton from Essex county at the soutli, is continuous for about 

 seven miles. From near Keeseville upon the Ausable, it lies above, and rests upon the pri- 

 mary, and extends in a northwest direction to Redford. From the latter place, it runs nearly 

 north over and in the direction of Rand's hill, to Ellcnburgh. The width of the belt occupied 

 by it is scarcely less than fifteen miles in the central part of Clinton, or from Plattsburgh west. 

 From Lake Champlain to the extreme west border of the calciferous sandstone, does not ex- 

 ceed in any place four miles ; and the remainder of this county, then, from the latter rock to the 

 western limit of the potsdam, is nearly the distance already stated. In this space, it is often 

 concealed beneath thick beds of drift ; in which drift, too, a great abundance of rounded masses 



