246 
GEOLOGY OF THE SECOND DISTRICT. 
in the quality of the ore which they furnish : different parts of the same vein appear to have 
different qualities, which often arise from causes not well understood; for example, where a 
trap dyke cuts through a mass of ore, it always changes the mode of its working, and, I 
believe, invariably increases the difficulty of its reduction ; and when reduced, it makes a 
a harder iron. The great veins of Adirondack, however, present a high degree of uniformity 
in the texture of their ores, in their mode of working, and in the quality of the resulting metal, 
and this uniformity is only equalled by a few of the minor beds in the counties of Essex 
and Clinton. This I conceive to be a very important fact; for it is perfectly plain that great 
advantages will always arise from uniformity in these respects, especially the latter. 
Again, the ores of all the beds of much consequence have a jointed structure, and break 
into tabular masses, and in this respect resemble the stratified rocks. This structure is not, 
however, due to stratification, but probably to crystallization; and it is also probable that 
this kind of structure is more distinct near the surface, and that as the beds are worked, 
less of it will appear. This will have some effect in the facility of raising the ore, which will 
become more compact the deeper the vein is worked, and freer from the seams or divisions 
necessary to allow the masses of ore to be laid hold of, in order to effect their separation from 
each other in certain directions. 
My examination of the relative position of these veins or beds has never enabled me to deter¬ 
mine whether the mass, as a whole, had a dip and line of bearing, or not. It will be seen by an 
inspection of one of the places, that minor veins occasionally project from the main mass, and 
pursue a given direction ; but where our observations have been directed to a vein as a whole, 
it has been very often followed by uncertainty whether it pursued, like an ordinary vein, a 
course which could be denominated its strike or line of bearing. A difficulty which of course 
contributes mainly to this result, is the uncertainly of distinct walls ; and where a mass of 
rock appears bounding the ore on one side, whether it was truly a wall, or a mass of rock in 
the midst of the bed or vein ; inasmuch, too, as such masses are not unfrequent, and, in the 
course of mining, run out, and disappear entirely from the vein. From this fact, it will be 
perceived how it happens that I have expressed myself vaguely in regard to the point whether 
these masses are truly veins; and as we have no assistance in determining the question from 
the presence of walls, except in some veins subordinate to a large mass, so we have none in 
the direction in which the outcrop of the ore appears on the surface; for though they are often 
situated in imperfect ranges as it regards each other, yet it is not clear that masses so situated 
are really beds or veins prolonged in such a direction. 
In all the uncertainty which lies over this subject, I am more disposed to believe that the 
whole valley of the Adirondack river is underlaid by the magnetic oxide. It is true that this 
belief borders on the extravagant, particularly when it is first suggested ; but after all, where 
is the extravagance in supposing that a mountain may be composed of iron ore, or a valley 
underlaid with it ? For aught that appears to the contrary, the interior of the earth may as 
well be composed of ore, as of rock or stony matter. In confirmation of the opinion 
expressed above, I shall have occasion to state many facts in the following pages. 
