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branches of the same rivulet which do not pass immediately near these fissures, remain cool and limpid; and thus you may with one hand touch one rill that is at the boiling point, and with the other hand touch another rill which is of the usual temperature of water in that climate. The exhalations of sulphur do not at all times proceed from the same fissures, but new ones appear to be daily formed, others becoming, as it were, extinct. On the margins of these fissures, and indeed almost over the whole place, are to be seen most beautiful crystallizations of sulphur, in many spots quite as fine and perfect as those from Vesuvius, or indeed as any other specimens I have ever met with. The whole mass of decomposed rock in the vicinity is, in like manner, quite penetrated by sulphur. The specimens which I collected of the crystallized sulphur, as well as of the decomposed and undecomposed porphyry, were left inadvertently on board the packet at Falmouth, which prevents my having the pleasure of exhibiting them to the Society. I did not perceive at this place any trace of pyrites, or any other metallic sub. stance, except indeed two or three small fragments of clay ironstone at a little distance, but did not discover even this substance any where in situ. It is very probable that the bed of the glen or ravine might throw some light on the internal structure of the place; but it was too deep, and its banks infinitely too precipitous, for me to venture down to it. I understood that there was a similar exhalation and deposition of sulphur on the side of a mountain not more than a mile distant in a straight line; and a subterranean communication is supposed to exist between the two places.

[De Borda, Journal des Mines, Geological Transact. Vol. I.]

CHAP. XVI.

ISLANDS SUDDENLY THROWN UP FROM THE SEA.

BESIDES the convulsions of nature displayed in volcanoes, other operations are carried on below the fathomless depths of the sea, the nature of which can only be conjectured of by the effects pro.

duced; nor is it more astonishing that inflammable substances should be found beneath the bottom of the sea, than at similar depths on land, and that there the impetuous force of fire should cause the imprisoned air and elastic gasses to expand, and by its mighty force drive the earth at the bottom of the sea above its surface. These marine volcanoes are perhaps more frequent, though they do not so often come within the reach of human observation, as those on land; since stupendous must be the operations carried on which never throw up matter to such an extent as man's ingenuity enables him to reach by fathoming.

Many instances have occurred, both in ancient and modern times, of islands being formed in the midst of the sea, and their appearance has always been preceded by violent agitations of the surrounding waters, accompanied with dreadful noises, and in some instances, with fiery eruptions from the new formed isles, which are composed of various substances, but frequently intermixed with a considerable quantity of volcanic lava. Such islands remain for ages barren, but in a long course of time become abundantly fruitful. It is obvious to enquire, whether springs are found on such new-created spots, when the convulsions which gave them birth have subsided; but on that point it is probable that no certain information has been obtained, as it does not appear that any naturalist has visited them for the purpose of recording their properties.

Among the writers of antiquity who have transmitted accounts of islands which have thus started up to the astonished spectator, Seneca asserts, that, in his time, the island of Therasea, in the Egean sea, was seen to rise in this manner, by some mariners who were sailing near the point of its ascent. Pliny gives a yet more wonderful account; for he says, that in the Mediterranean thirteen islands appeared at once emerging from the sea, the cause of which he ascribes rather to the retiring of the waters, than to any subterraneous energy; but he speaks of the island Hiera, near to that of Theresea, as formed by subterraneous explosions, and enumerates several others as derived from a similar origin, in one of which, he says, that fishes were found in great abundance, and that whoever ate of them died soon afterwards.

It is, however, to the Archipelago, and the Azores, that we

* Theresiam nostræ ætatis insulam spectantibus nostris in Egeo mari enatum. Quæst. Nat. lib. vi. cap. xxi.

must look for the grandest and most surprising instances of this phe. nomenon. Let us take an example or two from each of these groupes of islands.

The island of Acroteri, of no mean fame in ancient history, appears to have its surface composed of pumice stone, encrusted with a surface of fertile earth, and the ancients represent it as rising, in a violent earthquake, out of the sea. Four neighbouring islands have had a similar origin, and yet the sea is here of such a depth as to be unfathomable by any sounding-line. These arose at different times; the first long before the commencement of the christian æra, the second in the first century, the third in the eighth, and the fourth in 1573.

The following history, appertaining to the same cluster, is of still later date; and its peculiarities entitle it to a more minute detail:

On May 22, 1807, a severe earthquake was felt at Great Cammeni; and on the ensuing morning a party of seamen discovering not far off what they believed to be a wreck, rapidly rowed towards it; but finding rocks and earth instead of the remains of a ship, hasted back, and spread the news of what they had seen in Santorini. How great soever the apprehensions of the inhabitants were at the first sight, their surprise soon abated, and in a few days, seeing no appearance of fire or smoke, some of them ventured to land on the new island. Their curiosity led them from rock to rock, where they found a kind of white stone that cut like bread, which it nearly resembled in its form, colour, and consistence. They also found many oysters sticking to the rocks; but while they were employed in gathering them, the island moved and shook under their feet, upon which they ran with precipitation to their boats. With these motions and tremblings the island increased, not only in height, but in length and breadth; yet sometimes while it was raised and extended on one side, it sunk aud diminished on the other. Our author observed a rock to rise out of the sea, forty or fifty paces from the island, which having continued four days, sunk, and appeared no more; but several others appeared and disappeared alternately, till at last they remained fixed and unmoved. In the mean time the colour of the surrounding sea was changed: at first it was of a light green, then reddish, and afterwards of a pale yellow, accompanied with a noisome stench, which spread itself over part of Santorini.

On the 16th of July the smoke first appeared, not indeed from

the island, but from a ridge of black stones which suddenly rose about sixty paces from it, where the depth of the sea was unfathomable. Thus there were two separate islands, one called the White and the other the Black Island, from their different appearances. This thick smoke was of a whitish colour, like that of a lime-kilo, and was carried by the wind to Santorini, where it penetrated the houses of the inhabitants.

In the night between the 19th and 20th of July, flames began to issue with the smoke, to the great terror of the inhabitants of Santorini, especially those of the castle of Scaro, who were not above a mile and a half distant from the burning island, which now increased very fast, large rocks daily springing-up, which sometimes added to its length, and sometimes to its breadth. The smoke also increased, and there being no wind, it ascended so high as to be seen at Candia, and other distant islands. During the night it resembled a column of fire fifteen or twenty feet high, and the sea was then covered with a scurf or froth, in some places reddish, and in others yellowish, from which proceeded such a stench, that the inhabitants throughout the whole island of Santorini burnt perfumes in their houses, and made fires in the streets, to prevent infection. This indeed, did not last above a day or two, for a strong gale of wind dispersed the froth, but drove the smoke upon the vineyards of Santorini, by which the grapes, in one night, were parched up and destroyed. This smoke also caused violent head-achs, attended with retchings.

Ou the 31st of July, the sea smoked and bubbled in two different places near the island, where the water formed a perfect circle, and looked like oil when ready to boil. This continued above a month, during which many fishes were found dead on the shore of Santorini, The following night a dull hollow noise was heard, like the distant report of several cannon, which was instantly followed by flames of fire, shooting up to a great height in the air, where they suddenly disappeared. The next day the same hollow sound was several times heard, and succeeded by a blackish smoke, which, notwithstanding a fresh gale blew at that time, rose up in the form of a column to a prodigious height, and would probably in the night have appeared as if on fire.

On the 7th of August the noise was different; it resembled that of large stones thrown all together into a deep well. This noise

having lasted some days, was succeeded by another much louder, 30 nearly resembling thunder, as hardly to be distinguished from three or four real claps that happened at the same time.

On the 21st, the fire and smoke very considerably diminished; but the next morning broke out with greater fury than before. The smoke was red, and very thick, and the heat so intense, that all round the island the sea smoked and bubbled in a surprising man. ner. At night, by means of a telescope, sixty smaller openings or funnels, all emitting a very bright flame, were discovered upon the highest part of the island, conjointly resembling a large furnace; and there seemed to be as many more on the other side of the great volcano. On the 23d of August, in the morning, the island was much higher than the day before, and its breadth was increased by a chain of rocks sprung up in the night almost fifty feet above the water. The sea was also again covered with reddish froth, which always appeared when the island received any considerable additions, and occasioned an intolerable stench, till it was dispersed by the wind and the motion of the waves.

On the 5th of September, the fire opened another vent at the extremity of the Black Island, from which it issued for several days, during which but little was discharged from the large furnace: and from this new passage the astonished spectators beheld the fire dart up three several times to a vast height, resembling so many prodigious sky-rockets of a glowing lively red. The following night the subterraneous fire made a terrible noise, and immediately after a thousand sheaves of fire flew up into the air, where, breaking and dispersing, they fell like a shower of stars upon the island, which appeared all in a blaze, presenting to the amazed spectators at once a most dreadful and beautiful illumination. To these natural fire. works succeeded a kind of meteor, which for some time hung over the castle of Scaro, which is seated on a high rock in the island of Santorini, a meteor not unlike a fiery sword, and which served to increase the consternation of the inhabitants.

On the 9th of September the White and Black Íslands united, after which the western end of the island daily increased. There were now only four openings that emitted flames, which issued forth with. great impetuosity, sometimes attended with a noise like that of a large organ-pipe, and sometimes like the howling of wild beasts. On the 12th, the subterraneous noise became much augmented,

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