Part 5 (1/2)
To the north of Timor lie the Molucca Islands, several of which are volcanic. In one of them, named Machian, there occurred in the year 1646 an extraordinary event. A mountain was rent from top to bottom, sending out great columns of fire and dense vapours. The two parts now remain two distinct mountains.
In the Island of Sangir, another of the Moluccas, there was a violent eruption in March 1856. A large portion of the mountain fell down, and tremendous floods of water issued forth. The destruction that ensued was dreadful, upwards of two thousand persons having perished.
In another part of the Indian Ocean, near Madagascar, lies the little Isle of Bourbon, containing the volcano Salazes, which occasionally throws out the curious thready substance already mentioned, so strongly resembling spun gla.s.s.
CHAPTER XI.
Mud and Air Volcanoes--Luss--Macaluba--Taman--Korabetoff--New Island in the Sea of Azof--Jokmali--Fires of Baku--Mud Volcano in Flank of Etna--Air Volcanoes of Turbaco, Cartagena, and Galera-Zamba.
The curious mud volcano in the Island of Java, described in the preceding chapter, although presenting some peculiar features, is not the only one of the kind in the world. Mud, as you have learned, is often thrown out in great quant.i.ties, along with boiling water, even by true volcanoes, which at other times eject ashes and lava. But there are some volcanoes that never throw out anything else than mud and water, gas and steam. Such are called mud volcanoes or salses.
The most remarkable a.s.semblage of mud volcanoes in the world exists in the district of Luss, lying at the south-east corner of Beloochistan. They extend over a very large area, and are exceedingly numerous. The cone of one of them is no less than four hundred feet high, and the crater at the top is ninety feet in diameter. The mud in the crater is quite liquid, and is constantly disturbed by bubbles of gas, and occasionally by jets of the mud itself.
More familiarly known is the mud volcano of Macaluba, near Girgenti, in Sicily. It is situated in a country much impregnated with sulphur and other inflammable matters. The top of the hill is covered with dry clay, in which are numerous basins full of warmish water mixed with mud and bitumen. From these small craters bubbles of gas arise from time to time; but at long intervals they become much more active, and throw up jets of wet mud to the height of nearly two hundred feet. This mud smells strongly of sulphur.
In the peninsula of Taman, near the entrance to the Sea of Azof, there is a group of mud volcanoes, from one of which there was a considerable eruption on the 27th of February 1793. It was preceded by underground detonations, and accompanied by a column of fire and dense vapour, which rose to the height of several hundred feet. The discharge of mud and gas was abundant. The accompaniment of fire and smoke makes this eruption more nearly resemble that of a true volcano.
There is in the adjacent parts of the Crimea a mountain named Korabetoff, which also presents similar phenomena. On the 6th of August 1853, a column of fire and smoke was seen to rise from the top of this mountain to a great height, and it continued for five or six minutes. Two other similar but less violent ejections of fire and smoke followed at short intervals. These appearances were the accompaniments of an eruption of black fetid mud, which overspread the ground at the foot of the mountain to a considerable depth.
A still more striking phenomenon occurred in the Sea of Azof, on the 10th of May 1814. On that day a column of flame and very thick smoke arose out of the water, with a loud report like that of a cannon, and ma.s.ses of earth with large stones were tossed high up into the air. Ten eruptions of this kind succeeded each other at intervals of about a quarter of an hour; and after they had ceased for a time, they began again during the night. Next morning it was found that an island had risen out of the sea, between nine and ten feet in height, surrounded by a lower level of hardened mud. A strong fetid smell, probably that of petroleum, proceeded from the island, and extended for a considerable distance all round.
[Ill.u.s.tration: Air Volcanoes of Turbaco]
Another mud volcano, named Jokmali, near the Caspian Sea, was formed in November 1827. In this case, also, the ejection of mud was for several hours preceded by flames, rising to so great a height that they could be seen at a distance of twenty-four miles.
Large pieces of rock were at the same time thrown up and scattered to considerable distances all round. The entire district in which this mountain is situated, has its soil copiously impregnated with petroleum, and numerous wells are formed for its collection.
Quant.i.ties of this mineral oil are frequently found floating on the sea, along the neighbouring sh.o.r.es, where the sailors are in the habit of setting fire to this floating petroleum, while they dexterously steer their boats so as to avoid the flames. In this district also stands the city of Baku, held sacred by the Pa.r.s.ees, or fire-wors.h.i.+ppers, who have here built a temple, in which are kept burning perpetual fires, fed by the naphtha springing from the ground.
During the past year, 1866, a small mud volcano has been formed in the flanks of Mount Etna. It began with an outburst of strong jets of boiling water. First, one rose to the height of about six feet, then several others broke out, whereupon the height of the whole set diminished. There was much gas bubbling through the water, and some petroleum floated on its surface. It was very muddy, and left a thick deposit as it flowed away. Neither flames nor noise accompanied this eruption.
There are also diminutive volcanoes, consisting of small conical hills, from which nothing seems to be emitted but various sorts of gas. These are called air volcanoes. Such are those of Turbaco in South America, discovered by Baron Humboldt, who has left us a picture of them, of which you here have a copy. These volcanic hillocks are truncated cones, eighteen or twenty in number, composed of hardened mud, from 18 to 24 feet in height, and from about 140 to about 180 feet in diameter at the base. The small craters at the top are filled with liquid mud, whence bubbles of gas, chiefly nitrogen, are being continually disengaged.
There is a similar, but much larger, group in the neighbouring province of Cartagena. It consists of about one hundred cones spread over a district of nearly four hundred square leagues. There is also a group of about fifty cones within a range of four or five miles in the adjacent peninsula of Galera-Zamba. A sub-marine volcano, from which there have been several eruptions, is supposed to be connected with these numerous salses.
CHAPTER XII.
New Zealand--Boiling Fountains and Lakes
In the eruptions of mud volcanoes, described in the foregoing chapter, a frequent ingredient is boiling water. There are, however, several instances in which there are thrown up jets of boiling water that are not intermingled with mud, but in which the water is either pure or impregnated with some mineral which it holds in perfect solution. Of this nature are the Geysers of Iceland and California, already described.
In New Zealand there is another variety of this phenomenon, the boiling water issuing forth, not in intermittent jets, as in the Geysers, but in perpetually flowing springs, forming lakes, in which the water remains nearly at the boiling point. These springs and lakes occur at a place called Roto-Mahana. The annexed woodcut will convey an idea of their appearance.
There are several basins raised one above another, and all higher than the level of the large lake. The highest is of an oval form, and about two hundred and fifty feet in circ.u.mference. It is filled from an opening at the height of about a hundred feet above the level of the lower lake. At various stages below this upper basin are numerous other springs, from which several similar basins are filled. The whole of these basins empty themselves into the large lake below, and the water in all of them is nearly boiling hot, giving forth, with a hissing sound, volumes of white vapour.
[Ill.u.s.tration: Boiling Lakes of Roto Mahana]