230 
GEOLOGY OF THE SECOND DISTRICT. 
common, but in an amorphous state; and there are also a few poor veins of iron, or iron 
stone, in which the ore is in a state of peroxidation. 
The next mass of gneiss and hornblende reaches the lake shore about half a mile below 
Port Henry. An interesting place for the examination of these rocks is at the termination of 
the Potsdam sandstone, a few rods north of the furnace. A cove or small bay is formed by 
the projecting point of the sandstone, in consequence of the destruction of a large mass of 
primary limestone which intervenes between it and a high wall of gneiss. We find, first, the 
potsdam sandstone on the shore ; secondly, passing round this point of sandstone, we find the 
limestone ; and thirdly, the gneiss in a perpendicular precipice fifty or sixty feet high, against 
which the limestone formerly reposed. Following down the lake a little less than half a mile, 
we reach a place called Crag harbor. Here the gneiss and hornblende contain a vein of 
magnetic oxide of iron, twelve feet thick. The dip of the rocks, together with the direction 
of the vein, is changed from east to west, or in a direction opposite to the general inclination 
of the primary on the east side of the main range of mountains. This dip is, however, still 
found prevailing farther north, at the Walton, or as it is sometimes called the old Crown-Point 
ore bed. 
The rock of this narrow range is more distinctly stratified than that of most of the other 
localities upon the lake. The limestone of Port Henry, which has already been described, 
appears to divide; one branch terminates a little north of the furnace, while another wider 
branch pursues a course still farther westerly, so that the range of gneiss which forms the 
rock between Port Henry and Crag harbor passes between these two branches. 
The great body of gneiss of this county, however, is a wide belt which next succeeds, 
and of which Bald mountain forms a conspicuous part. This belt is about nine miles wide, 
and is an extension of the same mass which comes up from Warren county through Chester, 
Johnsburgh, and part of Schroon. It presents all the varieties usual in primary rocks ; but 
what is well worthy of special examination, is the gradual amalgamation of gneiss with hy- 
persthene rock. Contrary to the common representations in elementary works on geology, 
there is no passage of the latter beneath the former, so far as surface indications show; and 
the latter cannot therefore be said to rest upon the former, but they are imperceptibly incor¬ 
porated with each other. This range pursues a northeasterly course, and terminates along 
the shore of the lake in steep high walls, which are often perpendicular. Such is the case 
at the high rocks nearly opposite Basin harbor. The main portion of this range terminates at 
Split-rock; or it may be called the middle portion, as a branch still more westerly appears 
one mile west of Westport, and finally terminates in Willsborough upon the lake. 
The main range of gneiss and hornblende is important, in consequence of furnishing so 
many veins of iron ore : it forms a metalliferous district, and some of the veins are excellent 
for the quality of the iron they produce ; some portions of it are well adapted for castings, 
while others form a tough malleable iron. 
Although I have given the bounds and limits of the gneiss and hypersthene rock with as 
much precision as if they were strongly marked, still this is not strictly correct; for, though 
the latter is often well developed along this line, there are yet many examples of gneiss and 
