Other metallic ores are said to have been found among these mountains, and particularly those of gold and silver; but the accounts are vague and uncertain, and not to be credited.
The numerous Caves of this country present attractions to every, the least curious, traveller; and, in an eminent degree, to the mineralogist. They are crevices, or large chasms, probably worn in the rocks by the passage of water. This will, at first view, perhaps appear a bold assertion; but if it be recollected that they occur only in limestone, which is a soft rock, and (under certain circumstances,) soluble in water; that the rocks bear every mark of having been worn by water; and that streams of water are always found in them, it will not appear an improbable hypothesis. It is by no means difficult to believe that a stream, after having worn such a chasm as a cave presents, in the solid rock, may have found another channel; and, forsaking the old, have left room for nature to display some of her most beautiful works. A description of one of these caves will be a description of all; and we shall select Wier's Cave, in Rockingham County, Virginia, as it is the most curious of any with which we are acquainted.
The entrance of the cave is narrow and difficult. When the cave was first discovered, the passage into it was impeded by stalactites, which had formed perpendicular columns across it; but these are now removed. As we advance, our course is at first horizontal, but we soon descend fifteen or twenty feet by a ladder, and find ourselves in a large echoing cavern. Stalactites of a silvery whiteness are suspended from above, and pillars of stalagmites are rising around us. Ledges of rocks form our floor, and the uneven walls are incrusted over with a beautiful brown spar, which is sometimes suspended from the canopy in thin, shining, and translucent sheets. In passing on over the rugged rock of our pathway, our attention is divided between a care for our safety, and an admiration of the surrounding wonders.
Proceeding on through a narrower crevice in the rocks, we are soon introduced into other apartments, differing in shape and size from the first, but resembling it in the irregularity of its walls, floor, and covering, and in the calcareous incrustations and concretions, which, assuming a thousand fantastic shapes, and displaying a sparkling lustre, the more vivid as the light is stronger, give to this whole grotto the power of charming every beholder.
The cave is a mile and a half in extent, and extremely irregular in its course and shape. Its perpendicular height varies from three to forty feet, and its breadth from two to thirty. Its dividing branches are numerous, forming a great variety of apartments. The blue limestone appears frequently enough to satisfy us that it is the groundwork of the whole; but it is almost every where covered with incrustations of the hard carbonates. These hang from the arched vault above in clusters, and often reach the ground, forming massive columns. Stalagmites again rise from the floor like so many statues; the irregular sides of the ledges of rocks are often incrusted over with white crystals of the carbonate of lime, and have the appearance of banks of salt: at times we seem to walk on diamond pavements; again our footway is of rounded pebbles, and seems the bed of a river which had deserted its channel. Often we pass small streams of water; and the water is continually dripping from the ends of the stalactites, the echoing sound of which, when it drops, forms the only interruption to the profound silence which reigns throughout the cavern.
To give an idea of the diversified shapes which these concretions assume in the progress of their formation, (and they are constantly forming,) would be impossible. Suffice it to say, that there is scarcely any thing on earth to which they may not be supposed to form a resemblance; and yet, in fact, they are unlike any thing but themselves.
It is generally known that the earth in these caves contains the nitrates of lime, and potash, and other salts. The numerous caves which have been found in the Cumberland mountains and other parts of Tennessee, have been very productive of the nitrate of potash. In the investigation of the causes which have given origin to these salts, it may be recollected, that wild animals burrow in these caves; that when pursued by the hunter, they make them the places of their retreat, and probably die there; that the aborigines have made them a place of burial; and that the streams of water which flow through them in wet weather, carry with them not only great quantities of leaves but many other vegetable productions.
The natural bridge is celebrated as one of the greatest curiosities of the world. Viewed by a geologist, it would probably be considered as a cave (so to speak) unroofed in all but one place. It seems improbable that if the ravine had been made by a convulsion, which had split and separated the rock to the distance of fifty or sixty feet, any part of it, and particularly so large a mass as that which forms the bridge, should have been left, without exhibiting any marks of violence. The rock is limestone. It is known that this rock wears away rapidly under the attrition of water; and the supposition does not appear improbable, that, in the lapse of ages, so large a creek as that which flows below the bridge, may have worn as deep a ravine as that which now strikes us with so much surprise, In short, may not a cave have been originally formed where the ravine is now, and the pending portion of it have fallen in at every place except that which now forms this celebrated natural curiosity?
Mineral Springs.—The mineral springs of this region are numerous and diversified. Chalybeate springs are promiscuously scattered over the whole of it; and springs impregnated with sulphuretted hydrogen are quite common. Salt springs and licks are found more in the western than the eastern range of mountains. That which was first wrought by William King, is well known. The salt here is associated with gypsum. In the same range of mountains, farther to the southwest, there are now several other salt-works, and also one to the west, on Goose Creek, in Kentucky, which has been very productive.