OTHER GROTTOS AND CAVERNS.
There are few countries which have not to boast of a variety of natural excavations; and these have, from their extent, structure, and the curious phenomena they exhibit, in the formation of petrifactions, &c., been at all times objects of popular attention. Among those particularly deserving of notice are the following.
The volcanic country bordering on Rome, is peculiarly diversified by natural cavities of great extent and coolness; on which last account it is related by Seneca, that the Romans were accustomed to erect seats in their vicinity, to enjoy their refreshing chillness in the summer season. He gives a particular account of two such grottos belonging to the villa of Vatia; and it was in a place of this kind that Tiberius was nearly destroyed while at supper. Its roof suddenly gave way, and buried several of his attendants in its ruins; which so alarmed the others, that they fled and abandoned the emperor, with the exception of Sejanus, who, stooping on his hands and knees, and covering the body of Tiberius with his own, received all the stones which fell at that part from the roof, insomuch that, although he himself sustained considerable injury, the emperor escaped unhurt.
The grottos of the Cevennes mountains, in lower Languedoc, are both numerous and extensive. The principal one is not to be explored without much precaution, and without a safe guide. The entrance, which is low and narrow, leads to a spacious amphitheater, the petrifactions hanging from the roof of which have a most splendid effect by the light of torches. Hence the visitor has to descend to several chambers, one of which is named the Chamber of the Winds; another, of Echo; another, of the Cascade; another, again, of the Statue, &c.; on account of their exhibiting these different phenomena. In the grotto of Valori, at a small distance, the different natural curiosities which are to be found at every step, may be viewed at leisure, and without apprehension, as the visitor never loses sight of the light at the entrance, and is, therefore, not under any dread of not returning in safety. Here he is gratified by a view of the most singular petrifactions, representing flowers, fruits, bee-hives, and, in short, a variety of objects, in many of which the resemblance is nearly as accurate as if they had been sculptured.
In a wood, about five leagues from Besançon, in the province of France called Franche Comte, an opening, formed by two masses of rock, leads to a cavern more than nine hundred feet beneath the level of the country. It is in width sixty feet, and eighty feet high at the entrance, and exhibits inside an oval cavity of one hundred and thirty-five feet in breadth, and one hundred and sixty-eight in length. To the right of the entrance is a deep and narrow opening, bordered with festoons of ice, which, distilling in successive drops on the bottom of the cavern, form a mass of about thirty feet in diameter. A similar one, but somewhat smaller, produced by the water which drips in less abundance from the imperceptible fissures in the roof, is seen on the left. The ground of the cavern is perfectly smooth, and covered with ice eighteen inches thick; but the top, on the outside, is a dry and stony soil, covered with trees, and on a level with the rest of the wood. The cold within this cavern is so great, that, however warm the external atmosphere may be when it is visited, it is impossible to remain in it for any length of time.
These natural ice-houses are not unfrequent in France and Italy, and supply this agreeable luxury at a very cheap rate. Thus, in the same province, in the vicinity of Vesoul, is a cavern which, in the hot season, when it is eagerly sought, produces more ice in one day, than can be carried away in eight. It measures thirty-five feet in length, and in width sixty. The large masses of ice which hang pendent from the roof, have a very pleasing effect. When mists are observed in this cavern, they are regarded by the neighboring peasantry as infallible prognostics of rain; and it is worthy of observation, that although the water in the interior is always frozen in the summer, it becomes liquid in the winter season.
A grotto near Douse, also in Franche Comte, forms a similar ice-house, and is remarkable on account of the various forms of its congelations, which represent a series of columns, sustaining a curious vault, which appears to be carved with figures of men, animals, trees, &c.
The caverns of Gibraltar are numerous, and several of them of great extent. The one more particularly deserving attention is called St. Michael’s cave, situated on the southern part of the mountain. Its entrance is one thousand feet above the level of the sea, and is formed by a rapid slope of earth, which has fallen in at various periods, and which leads to a spacious hall, incrusted with spar, and apparently supported in the center by a large stalactitical pillar. To this succeeds a long series of caves, of difficult access. The passages leading from the one to the other are over precipices, which can not be passed without the aid of ropes and scaling-ladders. Several of these caves are three hundred feet beneath the upper one; but at this depth the smoke of the torches carried by the guides becomes so disagreeable, that the visitor is obliged reluctantly to give up the pursuit, and leave other caves unexplored. In these cavernous recesses, the process and formation of the stalactites is to be traced, from the flimsy quilt-like cone suspended from the roof, to the robust trunk of a pillar, three feet in diameter, which rises from the floor, and seems intended by nature to support the roof from which it originated.
The variety of forms which this matter takes in its different situations and directions, renders this subterraneous scenery strikingly grotesque, and in some places beautifully picturesque. The stalactites of these caves, when near the surface of the mountain, are of a brownish yellow color; but, in descending toward the lower caves, they lose the darkness of their color, which is by degrees shaded off to a pale yellow. Fragments are broken off, and, when wrought into different forms, and polished, are beautifully streaked and marbled.
About seven English miles from Adlersberg, in Carniola, is a remarkable cavern, named St. Magdalen’s cave. The road being covered with stones and bushes, is very painful; but the great fatigue it occasions is overbalanced by the satisfaction of seeing so uncommon a cavern. The visitor first descends into a hole, where the earth appears to have fallen in for ten paces, when he reaches the entrance, which resembles a fissure caused by an earthquake, in a huge rock. The torches are here lighted, the cave being extremely dark. This wonderful natural excavation is divided into several large halls, and other apartments. The vast number of pillars by which it is ornamented give it a superb appearance, and are extremely beautiful: they are as white as snow, and have a semi-transparent luster. The bottom is of the same materials; insomuch that the visitor may fancy he is walking beneath the ruins of some stately palace, amid noble pillars and columns, partly mutilated, and partly entire. Sparry icicles are everywhere seen suspended from the roof, in some places resembling wax tapers, which, from their radiant whiteness, appear extremely beautiful. All the inconvenience here arises from the inequality of the surface, which may make the spectator stumble while he is contemplating the beauties above and around him.
In the neighborhood of the village of Szelitze, in Upper Hungary, there is a very singular excavation. The adjacent country is hilly, and abounds with woods, the air being cold and penetrating. The entrance into this cavern, fronting the south, is upward of one hundred feet in hight, and forty-eight in breadth, consequently sufficiently wide to receive the south wind, which here generally blows with great violence; but the subterraneous passages, which consist entirely of solid rock, winding round, stretch still farther to the south. As far as they have been explored, their hight has been found to be three hundred feet, and their breadth about one hundred and fifty. The most inexplicable singularity, however, is, that in the midst of winter the air in this cavern is warm; and when the heat of the sun without is scarcely supportable, the cold within is not only very piercing, but so intense, that the roof is covered with icicles of the size of a large cask, which, spreading into ramifications, form very grotesque figures. When the snow melts in spring, the inside of the cave, where its surface is exposed to the south sun, emits a pellucid water, which congeals instantly as it drops, and thus forms the above icicles: even the water which falls from them on the sandy ground, freezes in an instant. It is observed, that the greater the heat is without, the more intense is the cold within; so that, in the dog-days, every part of this cavern is covered with ice. In autumn, when the nights become cold, the ice begins to dissolve, insomuch that, when the winter sets in, it is no longer to be seen; the cavern then is perfectly dry, and has a mild and gentle warmth. It is, therefore, not surprising that swarms of flies, gnats, bats, owls, and even great numbers of foxes and hares, resort thither, as to their winter retreat, and remain there till the return of spring.
MINES, METALS, GEMS, &C.
“Through dark retreats pursue the winding ore,
Search nature’s depths, and view the boundless store;
The secret cause in tuneful numbers sing,
How metals first were framed, and whence they spring:
Whether the active sun, with chymic flames,
Through porous earth transmits his genial beams
With heat impregnating the womb of night
The offspring shines with his paternal light:
Or whether, urged by subterraneous flames,
The earth ferments and flows in liquid streams;
Purged from their dross, the nobler parts refine,
Receive new forms, and with new beauty shine:
Or whether by creation first they sprung,
When yet unpoised the world’s great fabric hung:
Metals the bases of the earth were made,
The bars on which its fixed foundation’s laid:
All second causes they disdain to own,
And from the Almighty’s fiat sprung alone.”
The transition from the caverns and caves of the earth, to its MINES, and the various metals and gems they contain, is both natural and easy; and having dwelt on the former, we propose next to advert to the latter. By the word “mines” we understand those excavations, in which metals, minerals and precious stones are sought and found; and according to the substances which they yield they are variously spoken of as “gold mines,” “silver mines,” “lead mines,” &c., &c. The richest and most celebrated gold and silver mines are those of Mexico and Peru, in South America, and those lately discovered in California and Australia. Iron mines are more abundant, or at least more abundantly worked, in Europe than elsewhere, though the rapid increase of iron mining in the United States gives promise that our country may in this respect some day rival the old world. Copper mines have been found chiefly in England, Sweden and Denmark; and of late years copper has been found to be abundant in the region of our northern lakes. Lead and tin mines are numerous in England, the latter chiefly in the county of Cornwall; and lead is also found in abundance in the United States. Quicksilver mines abound principally in Hungary, Spain, Friuli, in the Venetian territories, and in Peru. Diamond mines are mainly in Brazil, and some in the East Indies; and salt mines are in Poland.
To explain the structure of mines, it should be observed that the internal parts of the earth, as far as they have been investigated, do not consist of any one uniform substance, but of various strata, or beds of substances, extremely different in their appearances, specific gravities and chemical qualities, one from another. Neither are these strata similar to each other, either in their nature or appearance, in different countries; insomuch that, even in the short extent of half a mile, sometimes, the strata will be found quite different in one from what they are in another place. As little are they the same either in depth or solidity. Innumerable cracks and fissures are found in all of them; and these again are so entirely different in size and shape, that it is impossible to form any inference from what may have been met with, relative to that which remains to be explored.
In Cornwall, the most common opinion entertained by the miners, is, that crude and immature minerals nourish and feed the ores with which they are intermixed in the mines; and that the minerals themselves will, in process of time, be converted into ores productive of those metals to which they have the nearest affinity, and with which they are most closely intermingled. And a distinguished professor, who is familiar alike with geology, chemistry and mineralogy, after visiting the mining districts of California, has given it as his opinion, that gold is constantly being formed there, by some powerful agency of nature which is still and steadily at work. And as a somewhat kindred view, Mr. Price, in his mineralogy of Cornwall, thinks it is most reasonable to conclude, that metals were made and planted in veins, at, or very soon after, the creation of the world; but that, in common with all other matter, they are subject to a degree of fluctuation, approaching to, or receding from, their ultimate degree of perfection, either quicker or slower, as they are of greater or less solid and durable frame and constitution. He supposes in every metal a peculiar magnetism, and an approximation of particles of the same specific nature, by which its component principles are drawn and united together; more particularly the matters left by the decomposition of the waters passing through the contiguous earths or strata, and deposited in their proper nidus or receptacle, until, by the accretion of more or less of its homogeneous particles, the metallic vein may be denominated either rich or barren.