Читать книгу The Mirror of Literature, Amusement, and Instruction. Volume 20, No. 583, December 29, 1832 - Various - Страница 1

Rock Bridges occupy the same pre-eminence amongst the sublimities of nature, that artificial bridges maintain amidst the labours of man. Both alike inspire us with admiration, though we are enabled to obtain but unequal results as to their respective origins. The bridge, built by human hands, is, indeed, a triumph of the perfection of skilful contrivance; the strength and beauty of the arch are among the most simple yet exquisite results of science, wonderful as they may appear to the untaught beholder: but how shall we explain the formation of stupendous rock-arches across deep ravines and rolling torrents, in countries where none but the wild and picturesque forms of nature rise to gladden the eye and heart of the inquiring traveller? Of the latter description are the natural bridges which abound in the State of Virginia; as Rockbridge, which gives name to the county in which it is situated, and the wild and fantastic bridges of Icognozo; all of which are more extensively recognised among the wonders of creation than the specimen here presented to the reader.

This Tunnel is in Scott county, Virginia; but was so little known beyond its immediate neighbourhood, as to induce Lieut.-Col. Long, (U.S. Army,) to communicate its description to Mr. Featherstonhaugh's American Journal of Geology and Natural Science; and the following narrative of the Colonel's Excursion will be read with interest:—

"During the past summer, I visited a remarkable natural bridge in Scott county, Virginia, to which I have given the name of Natural Tunnel, on account of its striking resemblance to artificial structures of that kind.

"The immediate locality of this tunnel is upon a small stream called Buck-eye, or Stock Creek. This last name owes its origin to its valley having been resorted to by the herdsmen of the country, for the attainment of a good range, or choice pasture-ground, for their cattle. The creek rises in Powell's mountain, and is tributary to Clinch river, which it enters at the distance of between two and three miles below the tunnel. The aspect of the surrounding country, and especially of that to the northward of the tunnel, and constituting the southerly slope of the mountain just mentioned, is exceedingly diversified, and broken by elevated spurs and ridges, separated from each other by deep chasms, walled with cliffs and mural precipices, often presenting exceedingly narrow passes, but occasionally widening into meadows or bottoms of considerable extent. The mural precipices just mentioned occur very frequently, bounding the valleys of the streams generally in this part of the country, and opposing ramparts of formidable height, and in many places utterly insurmountable. Such are the features peculiarly characteristic of Wild Cat Valley, the Valley of Copper Creek, of Powell's and Clinch rivers, and of numerous other streams of less note, all of which are situated within a few miles of the Natural Tunnel.

"To form an adequate idea of this remarkable and truly sublime object, we have only to imagine the creek to which it gives a passage, meandering through a deep, narrow valley, here and there bounded on both sides by walls, or revetements, of the character above intimated, and rising to the height of two or three hundred feet above the stream; and that a portion of one of these chasms, instead of presenting an open, thorough cut from the summit to the base of the high grounds, is intercepted by a continuous unbroken ridge, more than three hundred feet high, extending entirely across the valley, and perforated transversely at its base, after the manner of an artificial tunnel, and thus affording a spacious subterranean channel for the passage of the stream.

"The entrance to the Natural Tunnel on the upper side of the ridge is imposing and picturesque in a high degree; but on the lower side the grandeur of the scene is greatly heightened by the superior magnitude of the cliffs, which exceed in loftiness, and which rise perpendicularly—and, in some instances, in an impending manner—two or three hundred feet; and by which the entrance on this side is almost environed, as it were, by an amphitheatre of rude and frightful precipices.

"The observer, standing on the brink of the stream, at the distance of about one hundred yards below the debouchure of the Natural Tunnel, has, in front, a view of its arched entrance, rising seventy or eighty feet above the water, and surmounted by horizontal stratifications of yellowish, white, and grey rocks, in depth nearly twice the height of the arch. On his left, a view of the same mural precipice, deflected from the springing of the arch in a manner to pass thence in a continuous curve quite to his rear, and towering in a very impressive manner above his head. On his right, a sapling growth of buck-eye, poplar, linden, &c., skirting the margin of the creek, and extending obliquely to the right, and upward, through a narrow, abrupt ravine, to the summit of the ridge, which is here and elsewhere crowned with a timber-growth of pines, cedars, oaks, and shrubbery of various kinds. On his extreme right is a gigantic cliff, lifting itself up, perpendicularly from the water's edge, to the height, of about three hundred feet, and accompanied by an insulated cliff, called the Chimney, of about the same altitude, rising, in the form of a turret, at least sixty feet above its basement, which is a portion of the imposing cliff just before mentioned.

"Desirous of illustrating this paper by a front view of the Natural Tunnel where the creek issues from it, I have, with the assistance of a particular friend in this city—to whom I am indebted for the accompanying drawing1—been enabled to furnish a sketch which very faithfully represents some of the appearances I have described. The embellishments last mentioned, however, viz. the chimney and its accompaniments, could not be comprised in the landscape.

"The following passages are from my own private journal:—

"Saturday, Aug. 13, 1831. Having ascended Cove ridge, we turned aside from our route to visit the natural bridge, or tunnel, situated on Buck-eye, or Stock creek, about a mile below the Sycamore camp,2 and about one and a half miles from a place called Rye cove, which occupies a spacious recess between two prominent spurs of Powell's mountain, the site of the natural tunnel being included within a spur of Cove ridge, which is one of the mountain spurs just alluded to. Here is presented one of the most remarkable and attractive curiosities of its kind, to be witnessed in this or any other country. The creek, which is about seven yards wide, and has a general course about S. 15 W., here passes through a hill elevated from two to three hundred feet above the surface of the stream, winding its way through a huge subterraneous cavern, or grotto, whose roof is vaulted in a peculiar manner, and rises from thirty to seventy or eighty feet above its floor. The sides of this gigantic cavern rise perpendicularly in some places to the height of fifteen or twenty feet, and, in others, are formed, by the springing of its vaulted roof immediately from its floor. The width of the tunnel varies from fifty to one hundred and fifty feet. Its course is that of a continuous curve, resembling the letter S; first winding to the right as we enter on the upper side, then to the left, again to the right, and then again to the left on arriving at the entrance on the lower side. Such is its peculiar form, that an observer, standing at a point about midway of its subterranean course, is completely excluded from a view of either entrance, and is left to grope in the dark through a distance of about twenty yards, occupying an intermediate portion of the tunnel. When the sun is near the meridian, and his rays fall upon both entrances, the light reflected from both extremities of the tunnel contributes to mollify the darkness of this interior portion into a dusky twilight.

"The extent of the tunnel, from its upper to its lower extremity, following its meanders, is about 150 yards; in which distance the stream falls about ten feet, emitting, in its passage over a rocky bed, an agreeable murmur, which is rendered more grateful by its reverberations upon the roof and sides of the grotto. The discharge of a musket produces a crash-like report, succeeded by a roar in the tunnel; which has a deafening effect upon the ear.

"The hill through which this singular perforation leads, descends in a direction from east to west, across the line of the creek, and affords a very convenient passage for a road which traverses it at this place, having a descent in the direction just mentioned of about four degrees.

"The rocks found in this part of the country are principally sandstone and limestone, in stratifications nearly horizontal, with occasional beds of clay slate. A mixture of the two former frequently occurs among the alternations presented by these rocks. A variety of rock resembling the French burr occurs in abundance on Butcher's-fork of Powell's river, about twenty miles northwardly of the Natural Tunnel. Fossils are more or less abundant, in these and other rocks. Fossil bones, of an interesting character, have been found in several places. Saltpetre caves are numerous. Coves, sinks, and subterranean caverns, are strikingly characteristic, not only of the country circumjacent to the Natural Tunnel, but of the region generally situated between the Cumberland mountain, and the Blue ridge or Apalachian mountain. Bituminous coal, with its usual accompaniments, abounds in the northerly parts of this region; and in the intermediate and southerly portions, iron, variously combined, often magnetic, together with talcose rocks, &c. &c. are to be met with in great abundance.

"The mountains in this vicinity—long. 82° to 84° W. from Greenwich, lat. 35° to 36° N.—are among the most lofty of the Allegheny range. Several knobs3 in this part of the range, among which may be enumerated the Roan, the Unaka, the Bald, the Black, and Powell's mountains, rise to the height of at least four thousand five hundred feet above tide."

Mr. Featherstonhaugh remarks, that the Natural Tunnel has not been worn through the rock by the long-continued action of running water is evident, not from the cavernous structure alone of the general country, but from the form of Powell's mountain, in a spur of which the Tunnel passes transversely.

Mr. Featherstonhaugh further concludes the Tunnel to be a natural cavity in the rock, for, if such had not been the case, "it is evident that the stream would have been deflected from its line; would have followed the base of the hill, and have turned the extreme point."

Little is known of the geology of the country in which this Tunnel is situate, notwithstanding the popularity of the natural bridges of the State. The rock before us would appear to belong to that class which geologists commonly term Perforated Mountains, which some suppose to have been bored through, in part, at least, by the persevering industry of man. "Such phenomena," observes Maltebrun, "are, however, mere eccentricities of nature, and differ from caverns only from the circumstance of having a passage entirely through them. The Pierre-Pertuise in Mount Jura, and Pausilippo, near Naples, are instances of this kind. The Torghat, in, Norway, is pierced by an opening 150 feet high, and 3,000 long. At certain seasons of the year, the sun can be seen darting its rays from one extremity to the other of this vault. Near New Zealand is a rocky arch through which the waves of the sea pass at high water."4 The latter, one of the Piercy Islands, will be found engraved and described in The Mirror, vol. xix. p. 145.