THE PHLEGRÆAN FIELDS.
This celebrated region, which is situated between Baiæ and Naples, contains Monte Nuovo, Monte Barbaro, which is covered with vineyards, the Lake Avernus, formerly noted for its sulphureous vapours, and the Solfatara, or Lake of Sulphur, which has a stream of warm water flowing through it, containing so much carbonic acid gas that it appears to be actually boiling.
The Islands of Lipari are all volcanic. Lipari itself is remarkable for what are called its stoves. These consist of five caverns or grottoes, two of which cannot be entered on account of their intense heat. The stones even on the outside are so hot that they cannot be touched without giving pain; and from a slight crack or fissure in the floor of one of the grottoes, issues a thin stream of sulphureous vapour which is almost suffocating.
Vulcano, which has given the name to all the other burning mountains, is the next island to Lipari; and it was believed by the ancient Pagans, that in this island Vulcan erected the furnace at which he forged the thunderbolts of Jove, and hence the name. The mountain is in the form of a truncated cone, but it is merely a case enclosing another mountain, in which the crater or mouth of the volcano is situated; the outer case being open only on that side which is washed by the sea. The ground in this island is covered with large pieces of pumice stone, and if any of these be struck with a hammer, it gives out a low hollow sound, as though there were a large cavern below it. In March, 1786, the crater of this volcano threw out a prodigious quantity of sand, which covered every place in the neighbourhood to the depth of several feet, besides much more which fell into the sea.
Stromboli is the largest of the Lipari Islands, and the volcano is a conical mountain upwards of 2,000 feet high, and about nine miles in circumference; and it differs from the other volcanoes in being continually burning. It has also frequent explosions, which sometimes follow each other in quick succession; and as a shower of red hot stones is thrown up with each explosion, it closely resembles a bombardment of artillery. In some cases it is scarcely possible to land without danger, though the island has 1,200 inhabitants, and its vines produce some of the finest wines of the Mediterranean.
A volcanic island was elevated near Iceland in the year 1783; and shortly afterwards one of the minor volcanoes of that island threw out a stream of lava which completely choked up a river, and destroyed nearly twenty villages, and 9,000 human beings. This eruption produced the largest body of lava ever witnessed. The lava was in two streams, the longest of which was fifty miles, and the other forty miles in length; and both varied from seven to fifteen miles in breadth. The ordinary thickness was 100 feet, while in some places it was as much as 600 feet.
OTHER VOLCANIC ISLANDS.
There are several other islands of a similar nature in different parts of the world, but among the more remarkable may be mentioned the Sulphur Island in the Japanese Sea mentioned by Captain Basil Hall. The sulphuric volcano, from which the island takes its name, is on the north-west side. It emits white smoke, and a smell of sulphur is very strong on the lee side of the crater. The cliffs near the volcano are of a pale yellow, interspersed with brown streaks; the ground is very rugged; and on the top is a thin coat of brown grass. The south end of the island is of considerable height, of a deep blood-red colour, with here and there a spot of bright green. Sir Stamford Raffles, in his History of Java, records a fearful eruption, which occurred in the Island of Sumbawa on the 5th of April, 1815.
The sound of the explosions was heard at Sumatra, a distance of upwards of 900 miles; and of 12,000 persons who were on the island, only six and twenty survived the catastrophe. "This fearful visitation was accompanied by hurricanes, which carried up into the air men, horses, and other animals, and, uprooting the largest trees, scattered them on the surrounding sea; such a fall of ashes occurred during the eruption that they rendered houses uninhabitable which were forty miles from the volcano, and were carried in such quantities towards Java and Celebes as to darken the air for 300 miles; while those which fell into the sea to the west of Sumatra, formed a bed of two feet thick and several miles in extent, which impeded ships in their progress. In Java, in the day-time, these ashes produced a darkness more perfect than that of any night. The sea rose suddenly on the coast of Sumbawa and the adjoining islands from two to twelve feet, causing a wave, which rushed up the rivers, and then as suddenly subsided; and in one place overflowed a town called Tambora, and remained permanently at a depth of eighteen feet, on a spot where there had before been dry land. The area over which noises, and other indirect effects of this convulsion were perceived, was 1,000 English miles in circumference."
The Island of Owhyhee, in the Sandwich group, is all volcanic. It comprises an area of about 4,000 square miles, and its loftiest mountains are 15,000 or 16,000 feet above the level of the sea. The principal volcano is, however, about twenty miles from the sea-shore; and its crater is surrounded by steep rocks, forming an immense wall many miles in extent. "On visiting this crater," Mr. Ellis informs us, "he found it an immense gulf in the form of a crescent, about two miles in length, and one in breadth, and apparently about 800 feet deep. The bottom was covered with lava, forming one vast flood of burning matter in a state of terrific ebullition, rolling to and fro its 'fiery surge' and flaming billows. Fifty-one conical islands, of varied form and size, containing so many craters, rose either around the edge or from the surface of the burning lake. Twenty-two constantly threw out columns of grey smoke, or pyramids of brilliant flame; and several of these at the same time vomited from their burning mouths streams of lava, which rolled in blazing torrents down their black and rugged sides into the boiling mass below."
There are several other volcanoes in different parts of the world, particularly in the Andes, where some of the volcanoes vomit forth streams of boiling mud instead of fire; and in the Caucasian range, where the lava is mixed with naphtha. Many of the detached groups of islands have also been formed by volcanic action, and amongst others, the Philippine Isles.
CHAPTER IV. CAVERNS.
Caverns are naturally associated with mountains, as in most cases they are found together. A cavern has been defined to be an opening produced by nature in the solid crust of the earth, but it often appears to be the effect of crystallization. Caverns are generally divided into three classes, those which are merely wide clefts in the rock; those which admit daylight at both ends, and sometimes serve as the bed of a river; and those which consist of a succession of grottoes, united by openings or narrow passages, and often contain rivers. It is only the last kind that properly deserve the name of caverns, and there are some of immense size. When caverns are produced in limestone rocks, they are generally ornamented with stalactites, some of which are extremely beautiful, and which take an extraordinary variety of forms. New caverns are frequently being discovered; and doubtless many exist which are not yet known; as they appear to have been formed in the centre of a mass of melted rock, when the outside has cooled rapidly by imprisoned air or water; just as a bubble of air often forms a cavity in a mass of alum, or gum-varnish which has been melted to form some fancy article of female industry, and which has been suffered to cool too rapidly. All the largest caverns have a stream of water running through them.
ENGLISH CAVERNS.
These are very numerous, as limestone is not only very abundant in different parts of the country, but it has been so much worked, as to open most of its recesses. The following are a few of the most remarkable.
THE PEAK CAVERN.
The Peak Cavern is situated about 100 yards from the little town of Castleton in the romantic valley called Castleton-Dale, in Derbyshire. The valley, which is about six miles in length, and two in breadth, is celebrated for the beauty of its scenery. Near the entrance to the cavern, huge grey rocks rise almost perpendicularly to the height of nearly 300 feet on both sides, while on the left, a rapid rivulet foams over broken crags and masses of limestone. The mouth of the cavern is formed by a vast canopy of rock, which assumes the form of a depressed arch, nearly regular in its structure, 120 feet in width, forty-two feet high, and above ninety feet in receding depth. The effect of this magnificent natural vestibule is, however, entirely destroyed by the erection of a number of paltry looking posts, like those used for drying linen, and which are employed in making twine or rope; so that, to the disgrace of British taste, one of the grandest natural objects in Great Britain, is turned into a paltry rope walk. This is, indeed, suffering the spirit of commerce to pervade everything.
"After penetrating about thirty yards into the recess, the roof becomes lower, and a gentle descent conducts by a detached rock to the immediate entrance of the interior hollow, which is closed by a door kept locked by the guides. At this point, the light of day, which had gradually softened into the obscurity of twilight, totally disappears, and torches are employed to illuminate the progress through the darkness of the cavern. The passage then becomes low and confined, and the explorer is obliged to proceed twenty or thirty yards in a stooping posture, when he comes to another spacious opening, whence a path conducts to the margin of a small lake, locally called the 'First Water,' which is about fourteen yards in length, but has not more than three or four feet of depth. Here there is a small boat, partly filled with straw, on which the visitor lies down, and is conveyed into the interior of the cavern under a massive arch of rock, which is about five yards through, and in one place descends to within eighteen or twenty inches of the water. Beyond the lake, a spacious vacuity, 220 feet in length, 200 feet broad, and, in some parts, 120 feet high, opens in the bosom of the rocks, but the absence of light precludes the spectator from seeing either the sides or roof of this great cavern. It is traversed by a path, consisting partly of steps cut in the sand, conducting from the first to the 'Second Water.' Through this travellers are generally carried on the backs of the guides. Near the termination of this passage, before arriving at the water, there is a projecting pile of rocks, popularly called 'Roger Rain's House,' on account of the incessant fall of water, which trickles down in small drops like rain through the crevices of the rocks. A little beyond this is a tremendous hollow called the 'Chancel.' At this point the rocks appear broken and dislocated, and the sides and prominent parts of the cavity are incrusted with large masses of stalactite. In the 'Chancel,' the stranger is much surprised and impressed by hearing the death-like stillness of the place suddenly interrupted by a burst of vocal music from the upper regions of the cavern. The tones are wild and discordant, but heard in such a place, and under such circumstances, they produce a powerful impression. At the conclusion of the performance, the singers display their torches, and eight or ten women and children — the inhabitants of the huts at the entrance — appear, ranged in a hollow of the rock, about fifty or sixty feet from the ground, to which they gain access by clambering up a steep ascent which commences in the opening at the entrance of the hollow called the 'Chancel.' From the 'Chancel,' the path leads onward to the 'Devil's Cellar;' and thence a gradual but somewhat rapid descent of about 150 feet conducts to a spot called the 'Half-way House.' Neither of these places claim particular notice. Farther on, the way proceeds between three natural arches, pretty regularly formed, to another vast cavity which is denominated 'Great Tom of Lincoln,' from its resemblance to the form of a ball. A very pleasing effect is produced when this place is illuminated by a strong light. The arrangement of the rocks, the spiracles in the roof, and the flowing stream, unite to form a scene of no common interest. The distance from this spot to the termination of the entire hollow is not considerable. The vault gradually descends, the passage contracts, and at last nearly closes, leaving only sufficient room for the passage of the water, which appears to have a communication with the distant mines of the Peak Forest." The entire length of this wonderful excavation is about 2250 feet from the surface of the mountain, and its depth is 620 feet. In general, the access to the cavern is easy, but in very wet weather it cannot be explored, as it is then filled with water, which rises to a considerable height, even at the entrance.