Lipan Islands—Stromboli—Origin of Name—Position ofCrater—Description of Crater—New Volcanic Island namedJulia—Phenomena preceding its Elevation—Description of Islandand Crater—Its Disappearance—Rise of Islands at Santorin
The Lipari Islands are all of volcanic origin. The most interesting among them, for the length of time it has been in action and the constancy of its activity, is Stromboli. This name is a corruption of the ancient Greek name Στρογγυλη which was given to it because of its round swelling form. This is a very fussy little volcano, for it keeps perpetually puffing, growling, and fuming. It throws out columns of steam, and at intervals stones, cinders, and ashes, which are for the most part drifted by the wind into the sea. This restless volcano has been in almost uninterrupted activity since at least the third century before the Christian era —however much further back.
Several enterprising travellers have ascended to the crater of Stromboli. It was examined with great care in 1828 by M. Hoffmann, a celebrated Prussian geologist, who, while being held fast by his companions, leant over the crag immediately above the crater, and looked right down into one of its active mouths. He thus describes what he saw:—
"Three active mouths were seen at the bottom of the crater. The principal one, in the middle, was about two hundred feet in diameter; it shows nothing remarkable, only fuming slightly; and numerous yellow incrustations of sulphur coat the walls of its chimney. Close by this mouth is another, somewhat nearer the precipice, only twenty feet wide, in which I could observe the play of the column of liquid lava, which at intervals poised itself at a level. This lava did not look like a burning mass vomiting flames, but as glossy as molten metal—like iron issuing from the smelting furnace, or silver at the bottom of a crucible.
"This melted mass rose and fell—evidently urged by the powerful tension of elastic vapours pressing it upwards from beneath; and it was easy to perceive the balance of effect between the weight of the molten masses and the pressure of the steam which resisted them. The surface rose and fell rhythmically: there was heard a peculiar sound, like the crackling of air from bellows entering the door of a furnace. A bubble of white vapour issued at each crack, raising the lava, which fell down again immediately after its escape. These bubbles of vapour dragged to the surface of the lava red-hot cinders, which danced as if tossed by invisible hands in rhythmic sport above the brink of the opening.
"This play, so regular and attractive, was interrupted, every quarter of an hour or so, by more tumultuous movements. The mass of whirling vapour then rested motionless for a moment—even making a jerking motion of return, as if inhaled by the crater, from the bottom of which the lava rose more strongly as if to encounter it. Then the ground trembles, and the walls of the crater starting bend. It was quite an earthquake. The mouth of the crater uttered a loud rolling bellow, which was followed by an immense bubble of vapour, bursting at the surface of the lava with a loud thundering report. The whole surface of the lava, reduced to glowing splinters, was then tossed into the air.
[Illustration: Julia, or Graham's Island, in August 1831.]
"The heat struck our faces forcibly; while a flaming sheaf rose right into the air, and fell back in a shower of fire all around. Some bombs ascended to a height of about 1200 feet, and in passing over our heads described parabolas of fire. Immediately after such an eruption, the lava withdrew to the bottom of the chimney, which then yawned black and gaping. But erelong there was seen re-ascending the shining mirror of the surface of lava, which then recommenced the rhythmic play of its ordinary less violent bubblings."
What an agreeable visit this must have been! Don't you think, between ourselves, that the German philosopher must, on this occasion, have greatly resembled an Irishman in love, seeing he was so eager to reach the mouth of thecrater?
Before passing on to the description of other existing volcanoes, it may entertain you to hear something about Julia. This interestingcraterhad a short and troubled existence. She was not born like others of her name, but rose suddenly and majestically out of the sea, as the poets feign that Venus did of old. She did not, however, keep her head long above water, but after raging and fuming for about a couple of months, she plunged again under the waves. This happened in the year 1831.
On page 57 is a picture showing you how she looked in August of that year, about a month after she made her appearance. You see what a fury of acratershe must have been. It was a French philosopher (Constant Prévost) who christened her Julia; but it is hard to divine what prompted him to act so ungallantly. Perhaps, at the moment, he may have had in his eye some Julia of his acquaintance, with very red hair and a very fiery temper.
This volcanic island rose out of the Mediterranean, about midway between the Island of Pantellaria and the village of Sciacca on the southern coast of Sicily. From about the 28th of June to the 2nd of July 1831, the inhabitants of Sciacca felt several slight shocks, which they imagined to have proceeded from Etna. On the 8th of July the crew of a Sicilian ship, which was sailing at a distance of about six miles from Sciacca, suddenly observed in the sea a jet of water about 100 feet high. It rose into the air with a thundering noise, sustained itself for about ten minutes, and then fell down. Similar jets continued to rise in succession, at intervals of about a quarter of an hour, and produced a thick mist overspreading the surface of the sea, which was much agitated and covered with a reddish scum. Shoals of dead fishes were drifted on the waves. On the third day the jets were between 800 and 900 feet in diameter, and between 60 and 70 feet in height, while the steam from them rose to nearly 1800 feet.
On the 12th of July the inhabitants of Sciacca had their nostrils assailed by a strong smell of sulphur, and beheld the surface of the sea covered with black porous cinders, which, being drifted ashore, formed a bed of some thickness on the beach. So great was the drift of volcanic ashes, that boats could hardly struggle through the water, and multitudes of dead fishes floated on its surface. Next morning they saw rising out of the sea a column of dark vapour, which, however, towards night became lurid red. From time to time, during both the day and night, they heard loud reports, and saw bright sparks of fire through the dusky vapour.
[Illustration: Julia, or Graham's Island, on 29th September 1831.]
On the 18th of July the captain of the Sicilian ship discovered that an island had arisen out of the sea at the spot whence the appearances before described had proceeded. It had already attained a height of nearly twelve feet, and had in its centre a crater, which vomited forth immense jets of steam, along with ashes, cinders, stones, &c. The water which boiled in this crater was reddish, and the cinders, which covered the sea all round the island, were of a chocolate colour. The island subsequently attained a height of upwards of 90 feet at its highest point, and a circumference of about three-quarters of a mile. A channel of communication was also opened between the sea and the interior of the crater, which had a diameter of about 650 feet. The vapours and other matters thrown up from the mouth of the volcano formed a luminous column upwards of 200 feet in height.
On the 29th of September it was visited by the French gentleman who gave it the name of Julia, and it then presented the appearance which we have sketched. He landed with a party and proceeded to examine the crater, in which he found a circular basin filled with reddish water, almost boiling hot, and fresh. This basin was nearly 200 feet in diameter. There rose from the water bubbles of gas, which made it appear as if it were boiling. The water was not quite at the boiling point, however, yet the bubbles of gas were sufficiently hot to burn the fingers.
[Illustration: Crater of Julia, or Graham's Island.]
These bubbles rose from a great depth, and each, on bursting, which it did with a feeble report, threw out sand and cinders. At a short distance from the crater there rose sulphurous vapours, which deposited sulphur and salt. The loose dust and ashes forming the soil of the island were hot, and walking on them was difficult. The foregoing woodcut will give you an idea of the appearance which the crater presented to those visitors.
In the following month of October nothing remained of this wonderful island but a hillock of sand and cinders; and at the end of six months it had quite vanished. Soundings taken a few years ago show ten feet of water over the spot, so that, although the island has disappeared, there is still a shoal left behind. This temporary volcano is best known in England under the name of Graham's Island; so called after an English naval officer of that name, who was the first to set foot on it, and who planted upon it the English flag, so claiming it for his sovereign. The Sicilians allege this to be the reason why it disappeared so soon—that it was in a hurry to escape from under the English yoke.
Similar phenomena have been taking place during the past year, 1866, in the Bay of Santorin, situated in the island of that name, which lies to the northward of Crete. There are several islands in the bay, all apparently of volcanic origin, and one of them was thrown up about three centuries before the beginning of the Christian era. Last year their number was increased by a series of eruptions similar in their attendant circumstances to those which accompanied the upheaval of Julia. The first warnings were given on the 30th of January 1866, by low underground rumblings, and slight movements of the ground at the south end of New Kammeni, one of the formerly upheaved islands in the bay. Next day these phenomena increased in violence, and quantities of gas bubbled up from the sea. On the 1st of February, reddish flames ascended from the water, and on the 2nd there rose, out of the harbour of Voulcano, an island, which was christened "George." The volcanic agitation was prolonged during February and March—the upheaval of other two islands being the result. Whether these additional islands will continue permanently above water remains to be seen.
Peak of Teneriffe—Its Crater—Eruption of Chahorra—Palma—GreatCaldera—Lancerote—Great Eruption—Sudden Death—Fuego, Cape deVerde Islands—Cotopaxi—Its Appearance—Great EruptiveForce—Tunguragua—Great Eruption of Mud and Water—Fish thrownout—Quito—Its Overthrow—Pichinca—Humboldt's Ascent—NarrowEscape—Antisana—Sangay—Rancagua—Chillan—Masaya
The Island of Teneriffe is celebrated for its magnificent snow-clad peak. On referring to the woodcut of this volcano at page 11, you will observe in what a sharp point the cone terminates, and how slender is the column of vapour at its summit. The crater at the top is comparatively small—its greatest diameter being 300, and its smallest 200 feet, while its depth is only about 100 feet. From this crater there has been no eruption since 1706, when the finest harbour in the island was destroyed. But from the side of the peak there rises a supplementary mountain named Chahorra, on the top of which there is also a crater, whence there was an eruption in 1798. So great was its violence, that masses of rock were thrown to a height of upwards of 3000 feet. In the neighbouring island of Palma there is a volcanic crater named the Great Caldera, whose depth is said to be upwards of 5000 feet.
Almost due east of Palma, and much nearer the African coast, lies the Island of Lancerote, on which are a great many volcanic cones, arranged nearly in a straight line. These were for the most part formed by a long series of eruptions which took place during the years from 1730 to 1736. Such immense quantities of lava were poured forth in the course of those six years, that about a third of the surface of the island was covered by them, and many towns and villages were destroyed. St. Catalina, a populous and thriving town, was first overflowed by a lava-stream, and then a new crater burst forth on its very site, raising over it a hill 400 feet high. All the cattle in the island fell down dead in one day, and nearly about the same time—they were suffocated by deadly vapours that rose from the ground. The volcanic activity of this island was renewed in August 1824, when there was formed, near the port of Rescif, a new crater, which vomited forth such quantities of stones, ashes, and other volcanic matters, that in the short space of twenty-four hours they formed a hill of considerable height.
The Cape de Verde Islands, lying to the south-westward of the Canaries, are also volcanic. In 1847 a volcano named Fuego, situated in one of them, after remaining at rest about fifty years, burst into fresh activity. No less than seven new vents were formed; and from these were poured forth great streams of lava, which wrought immense damage in the cultivated parts of the island. The inhabitants sustained great loss by the destruction of their cattle and crops.
Passing over to the South American continent, we come to the range of the Andes, which contains numerous volcanoes. Among these the most conspicuous is Cotopaxi, the highest volcano in the world, situated in the territory of Quito. So perfect is the form of the cone, that it looks as if it had been turned in a lathe. Its coating of snow gives it a dazzling appearance, and so sharply is the snow-line defined that it seems almost as if the volcano-king wore a white night-cap instead of a crown.
The eruptions of this mountain are rare. One of the greatest of them lasted for three years, and desolated an immense extent of country with floods of lava. On this occasion, it is said, columns of fire rose to the height of nearly 5000 feet, so great was the energy of the volcanic force.
A little to the southward of Cotopaxi, but concealed from it by the intervening mass of Chimborazo, lies the volcano of Tunguragua, from which there was an extraordinary eruption in the year 1797, that proved very destructive to the cities in its neighbourhood. Indeed, so terrible was the convulsion of the ground, which lasted four minutes, that the cities of Riobamba and Quero were reduced to heaps of ruins. Then the base of Tunguragua was rent, and from numerous apertures there were poured out streams of water and mud, the latter gathering in the valleys to the depth of 600 feet. This mud spread itself far and wide, blocking up the channels of rivers, and forming lakes, which remained upwards of two months. But, strangest of all, quantities of dead fishes were found in the water which burst from the volcano. These fishes are supposed to have been bred in subterranean lakes contained in caverns in the interior of the mountain, considerably removed from the volcanic fires in the centre. It is probable that, when the rent was formed near the base, one of those caverns was broken open, and that the waters from it were discharged along with their finny inhabitants.
Here is a picture of one of those fishes, which was taken by Baron Humboldt. When you see what a queer-looking fish it is, you will wonder the less at its having chosen so strange an abode.
[Illustration: Pimelodus Cyclopum]
Quito, the capital of the province of that name, is the highest of cities—being situated at an elevation of between nine and ten thousand feet above the level of the sea. It is built on a plain, lying on the flanks of the volcano Pichinca, of which a view is given in the annexed woodcut. Poor Quito has suffered severely from this dangerous neighbourhood; for, on the 22nd of March 1859, a violent shaking of the mountain laid the whole city in ruins.
Pichinca, you will observe, has a most irregular outline, but very graceful withal. Instead of a single cone like Cotopaxi, it has a group of cones, some of which are very pointed. It has four principal summits, of which the most southerly contains the active crater. Here the celebrated traveller Baron Humboldt nearly lost his life. Having ascended the cone and approached the edge of the crater, he peered into the depths of the dark abyss, and there beheld the glowing lava boiling as if in a huge caldron. A thick mist coming on, he unwarily advanced to within a few feet of the rapid slope descending into the crater, and was within an ace of toppling over into the fiery gulf beneath. What a pity it would have been had he fallen in! We should have had no "Personal Narrative," no "Cosmos."
[Illustration: Pichinca]
There are in this region of South America other two great volcanoes, named Antisana and Sangay. The former has not been in action since 1718, but is remarkable for the immense beds of lava which it has amassed around it during its former eruptions. Sangay, again, has ever since 1728 been in a state of almost perpetual activity—in this respect resembling Stromboli, which, however, it far exceeds in height, its summit being nearly 18,000 feet above the level of the sea. The eruptions of this mountain are accompanied by loud explosions, which are heard at great distances, and they succeed each other with immense rapidity. The fumes emitted are sometimes gray, sometimes orange; and the matters ejected are cinders, dross, and spherical masses of stone. These last are often two feet in diameter, and in strong explosions as many as sixty of them may be thrown out at a time. They are glowing at a white heat, and for the most part they fall back into the vent of the crater. Sometimes, however, they alight on the edge of the cone—imparting to it a temporary brilliancy; but the mass of the cone, being composed of loose black cinders, has a most dismal aspect.
Another very active South American volcano is Rancagua in Chili. It is, however, of moderate height, and thus in its general character resembles Stromboli, which it rivals in restlessness. Another of the volcanoes of Chili, named Chillan, which had long been in a state of repose, renewed its activity in November 1864. Its usually snow-clad summit became covered in a short time with a thick layer of volcanic ashes, which greatly altered its appearance. Streams of lava were also thrown out by the mountain on this occasion.
There are several volcanoes in Central America. One of them, named Masaya, was very active during the sixteenth century. It is situated near the lake of Nicaragua, in the territory of that name. It was visited in 1529 by the Spanish historian Gonzales Fernando de Oviedo, from whose description it seems to have presented phenomena resembling those seen in the crater of Stromboli. "In its ordinary state," he says, "the surface of the lava, in the midst of which black scoriae are continually floating, remains several hundred feet below the edges of the water. But sometimes there is suddenly produced an ebullition so violent, that the lava rises almost to the very brim."
Jorullo—Great Monument—Jorullo's Estate—Interruption to hisQuiet—His Estate Swells—Swallows Two Rivers—Throws upOvens—Becomes a Burning Mountain—Popocatepetl—SpanishAscents—Orizaba —Muller's Ascent—Morne-Garou—Pelée—-LaSoufriere
What a fortunate man was Mr. Jorullo! Old Cheops, king of Egypt, spent vast sums of money, many long years, and the labour of myriads of his subjects, in erecting the Great Pyramid as a monument to his memory. But Mr. Jorullo, without his having to lay down a single Mexican dollar, and without any labour, either of his own or of his servants, had a magnificent monument raised to his memory in a single night. Jorullo's monument, too, is far bigger than the pyramid of Cheops—being nearly four times the height, and occupying a much larger extent of ground. Whether it will last as long as the pyramid has done, time only can show.
You would doubtless like to know how this great monument was reared. Here is the story:—Don Pedro di Jorullo was a Mexican gentleman who lived about the middle of the last century. He was a landed proprietor—the owner of a nice little farm of great fertility, situated to the westward of the city of Mexico, and about ninety miles from the coast of the Pacific Ocean. The ground was well watered by artificial means, and produced abundant crops of indigo and sugar-cane. Thus Mr. Jorullo was a very thriving well-to-do sort of man.
[Illustration: Jorullo]
This gentleman's prosperity continued without interruption till the month of June 1759, when, to the great alarm of his servants dwelling on the estate, strange underground rumblings were heard, accompanied by frequent shakings of the ground. These continued for nearly two months; but at the end of that time all became quiet again, and Mr. Jorullo's servants slept in fancied security. On the night of the 28th of September, however, their slumbers were suddenly broken by a return of the horrible underground rumblings—thundering more loudly than before. The next night, these subterranean thunders became so loud, that the Indian servants started from their beds, and fled in terror to the mountains in the neighbourhood. Gazing thence, after day had dawned, they beheld to their astonishment that a tract of ground from three to four square miles in extent, with their master's farm in the middle of it, had been upheaved in the shape of an inflated bladder. At the edges this singular elevation rises only about thirty-nine feet above the old level of the plain; but so great is the general convexity of the mound, that towards the centre it swells up to five hundred and twenty-four feet above the original level.
The Indians affirmed that they saw flames issue from the ground throughout an extent of more than half a square league, while fragments of burning rocks were thrown to enormous heights. Thick clouds of ashes rose into the air, illuminated by glowing fires beneath; and the surface of the ground seemed to swell into billows, like those of a tempestuous sea. Into the vast burning chasms, whence these ejections were thrown, two rivers plunged in cataracts; but the water only increased the violence of the eruption. It was thrown into steam with explosive force, and great quantities of mud and balls of basalt were ejected. On the surface of the swollen mound there were formed thousands of small cones, from six to ten feet in height, and sending forth steam to heights varying from twenty to thirty feet.
Out of a chasm in the midst of these cones, or ovens, as the natives call them, there rose six large masses, the highest of which is sixteen hundred feet in height, and constitutes the volcano of Jorullo. The eruptions of this central volcano continued till February 1760 with extreme violence—the crater throwing out large quantities of lava; but in the succeeding years it became less turbulent in its activity. It still, however, continues to burn; and the mountain emits from the wide crater at its summit several jets of vapour. The foregoing woodcut gives a view of this volcano, and of the little steaming ovens which stud the whole ground around it, giving it at a distance the appearance of the sea in a storm. And now confess that Mr. Jorullo's monument is far grander than the pyramid of Cheops. Surely the loss of his farm was amply compensated to him, by the perpetuation of his memory and his name, through the rearing of such a marvellous cenotaph.
For a long time after the first eruption, the ground for a great distance round the volcano was too hot to be habitable or capable of cultivation. It is now, however, so much cooled down, that it is once more covered with vegetation; and even some small portions of the raised ground containing the ovens have been again brought under culture.
Besides this volcano, so recent in its origin, Mexico contains other five—Orizaba, Toluca, Tuxtla, Popocatepetl, and Colima. What is rather remarkable, these five, together with Jorullo, all lie nearly in a straight line running east and west. The tracts of country which these volcanoes have desolated with their lavas are called by the Mexicans the "Malpays."
The most remarkable of these mountains is Popocatepetl. Although it has long remained in comparative quiet, it was very active at the time of the Spanish invasion under Cortés. Of the first approach of the Spaniards to this volcano, and of the attempts made by some of them to climb to the top, Mr. Prescott, in his history of the conquest of Mexico, gives the following graphic account:—
"They were passing between two of the highest mountains on the North American continent, Popocatepetl, 'the hill that smokes' and Iztaccihuatl, or 'white woman;' a name suggested, doubtless, by the bright robe of snow spread over its broad and broken surface. A puerile superstition of the Indians regarded these celebrated mountains as gods, and Iztaccihuatl as the wife of her more formidable neighbour. A tradition of a higher character described the northern volcano as the abode of the departed spirits of wicked rulers, whose fiery agonies in their prison-house caused the fearful bellowings and convulsions in times of eruption. It was the classic fable of antiquity. These superstitious legends had invested the mountain with a mysterious horror, that made the natives shrink from attempting its ascent, which, indeed, was, from natural causes, a work of incredible difficulty.
"The greatvolcan, as Popocatepetl was called, rose to the enormous height of 17,852 feet above the level of the sea; more than 2000 feet above the 'monarch of mountains'—the highest elevation in Europe. During the present century it has rarely given evidence of its volcanic origin, and 'the hill that smokes' has almost forfeited its claim to the appellation. But at the time of the conquest it was frequently in a state of activity, and raged with uncommon fury while the Spaniards were at Tlascala; an evil omen, it was thought, for the natives of Anahuac. Its head, gathered into a regular cone by the deposit of successive eruptions, wore the usual form of volcanic mountains, when not disturbed by the falling in of the crater. Soaring towards the skies, with its silver sheet of everlasting snow, it was seen far and wide over the broad plains of Mexico and Puebla; the first object which the morning sun greeted in his rising, the last where his evening rays were seen to linger, shedding a glorious effulgence over its head, that contrasted strikingly with the ruinous waste of sand and lava immediately below, and the deep fringe of funereal pines that shrouded its base.
"The mysterious terrors which hung over the spot. and the wild love of adventure, made some of the Spanish cavaliers desirous to attempt the ascent, which the natives declared no man could accomplish and live. Cortés encouraged them in the enterprise, willing to show the Indians that no achievement was above the dauntless daring of his followers. One of his captains, accordingly, Diego Ordaz, with nine Spaniards, and several Tlascalans, encouraged by their example, undertook the ascent. It was attended with more difficulty than had been anticipated.
"The lower region was clothed with a dense forest, so thickly matted, that in some places it was scarcely possible to penetrate it. It grew thinner, however, as they advanced, dwindling by degrees into a straggling stunted vegetation, till, at the height of somewhat more than 13,000 feet, it faded away altogether. The Indians, who had held on thus far; intimidated by the strange subterraneous sounds of the volcano, even then in a state of combustion, now left them. The track opened on a black surface of glazed volcanic sand and of lava, the broken fragments of which, arrested in its boiling progress in a thousand fantastic forms, opposed continual impediments to their advance. Amidst these, one huge rock, the Pico del Fraile, a conspicuous object from below, rose to the perpendicular height of 150 feet, compelling them to take a wide circuit. They soon came to the limits of perpetual snow, where new difficulties presented themselves, as the treacherous ice gave an imperfect footing, and a false step might precipitate them into the frozen chasms that yawned around. To increase their distress, respiration in these aerial regions became so difficult, that every effort was attended with sharp pains in the head and limbs. Still they pressed on, till, drawing nearer the crater, such volumes of smoke, sparks, and cinders were belched forth from its burning entrails, and driven down the sides of the mountain, as nearly suffocated and blinded them. It was too much even for their hardy frames to endure, and, however reluctantly, they were compelled to abandon the attempt on the eve of its completion. They brought back some huge icicles—a curious sight in those tropical regions—as a trophy of their achievement, which, however imperfect, was sufficient to strike the minds of the natives with wonder, by showing that with the Spaniards the most appalling and mysterious perils were only as pastimes. The undertaking was eminently characteristic of the bold spirit of the cavalier of that day, who, not content with the dangers that lay in his path, seemed to court them from the mere Quixotic love of adventure. A report of the affair was transmitted to the Emperor Charles V.; and the family of Ordaz was allowed to commemorate the exploit by assuming a burning mountain on their escutcheon.
"The general was not satisfied with the result. Two years after he sent up another party, under Francisco Montano, a cavalier of determined resolution. The object was to obtain sulphur to assist in making gunpowder for the army. The mountain was quiet at the time, and the expedition was attended with better success. The Spaniards, five in-number, climbed to the very edge of the crater, which presented an irregular ellipse at its mouth, more than a league in circumference. Its depth might be from 800 to 1000 feet. A lurid flame burned gloomily at the bottom, sending up a sulphureous steam, which, cooling as it rose, was precipitated on the sides of the cavity. The party cast lots, and it fell on Montano himself to descend in a basket into this hideous abyss, into which he was lowered by his companions to the depth of 400 feet! This was repeated several times, till the adventurous cavalier had collected a sufficient quantity of sulphur for the wants of the army."
The more tranquil state of the volcano in modern times having rendered the summit no longer so difficult of access as it was in those days, the ascent has been several times achieved—twice in 1827, and again in 1833 and 1834. The crater is now a large oval basin with precipitous walls, composed of beds of lava, of which some are black, others of a pale rose tint. At the bottom of the crater, which is nearly flat, are several conical vents, whence are continually issuing vapours of variable colour, red, yellow, or white. The beds of sulphur deposited in this crater are worked for economical purposes. Two snowy peaks tower above its walls.
Not less magnificent in its proportions is the volcano of Orizaba, which is nearly of the same height as Popocatepetl. It was very active about the middle of the sixteenth century, having had several great eruptions between 1545 and 1560; but since then it has sunk into comparative repose. This mountain was ascended by Baron Muller in 1856. A first attempt proved unsuccessful; but by passing a night in a grotto near the limit of perpetual snow, he was able on the following day, after a toilsome ascent, to reach the edge of the crater—not, however, till near sunset. His experiences, and the scene which was presented to his wondering gaze, he describes in the following terms:—
"I have achieved my purpose, and joy banishes all my griefs, but only for a moment; suddenly I fell to the ground, and a stream of blood gushed from my mouth.
"On recovering, I found myself still close to the crater, and I then summoned all my strength to gaze and observe as much as possible. My pen cannot describe either the aspect of those regions, or the impressions they produced on me. Here seemed to be the gate of the nether world, enclosing darkness and horror. What terrible power must have been required to raise and shiver such enormous masses, to melt them and pile them up like towers, at the very moment of their cooling and acquiring their actual forms!
"A yellow crust of sulphur coats in several places the internal walls, and from the bottom rise several volcanic cones. The soil of the crater, so far as I could see, was covered with snow, consequently not at all warm. The Indians however affirmed that, at several points, a hot air issues from crevices in the rocks. Although I could not verify their statement, it seemed to me probable; for I have often observed similar phenomena in Popocatepetl.
"My original intention of passing the night on the crater had for overpowering reasons become impracticable. The twilight which, in this latitude, as every one knows, is extremely short, having already begun, it was necessary to prepare for our return. The two Indians rolled together the straw mats which they had brought, and bent them in front so as to form a sort of sledge. We sat down upon these, and stretching out our legs, allowed ourselves to glide down on this vehicle. The rapidity with which we were precipitated increased to such a degree, that our descent was rather like being shot through the air, than any other mode of locomotion. In a few minutes we dashed over a space which it had taken us five hours to climb."
There are several of the West Indian islands of volcanic origin; and three of them—St. Vincent, Martinique, and Guadaloupe—contain active volcanoes. The most remarkable is the volcano of Morne-Garou, in St. Vincent, the eruptions from which have been particularly violent. In 1812 the ashes which it threw out were so great in quantity, and projected to so vast a height, that they were carried to a distance of two hundred miles in the teeth of the trade-wind. From Mount Pelée, in Martinique, there was an eruption in August 1851. La Soufriere, the volcano in Guadaloupe, is said to have been cleft in twain during an earthquake. Its activity has long been in a subdued state; but it is remarkable for its deposits of sulphur.
Hawaii, Sandwich Islands—Crater of Kilauea—Its awful Aspect—FieryLake and Islands—Jets of Lava—Depth of Crater and Surfaceof Lake—Bank of Sulphur—Curious Rainbow—Mouna-Kaah andMouna-Loa—Eruption of the Latter in 1840—Recent Eruption—GreatJet and Torrent of Lava—Burning of the Forests—GreatWhirlwinds—Underground Explosions—Other Volcanoes in the Pacific.
Hawaii is well known in history as being the island where the celebrated navigator Captain Cook was killed. The name used to be written Owhyhee; but a better apprehension of the native pronunciation has led to its being altered into Hawaii. No one who visits it in the present day need be afraid of sharing the fate of poor Captain Cook; for the descendants of the savages who, in his time, inhabited the island, have now, through the labours of Christian missionaries, become a very decent sort of quiet, well-behaved Christian people.
Hawaii, which is the largest of a group called the Sandwich Islands, can boast of the greatest volcanic crater in the world. It is called sometimes Kirauea, sometimes Kilauea; for the natives seem not very particular about the pronunciation of theirland theirr; but where one useslanother as pertinaciously employsr, while a third set use a sound between the two, as you may have heard some people do at home. Situated on the lower slopes of a lofty mountain called Mouna-Roa, or Loa (for there is the same dubiety about theland therhere as in the former case), the crater of Kilauea is a vast plain between fifteen and sixteen miles in circumference, and sunk below the level of its borders to a depth varying from two hundred to four hundred feet—the walls of rock enclosing it being for the most part precipitous. The surface of the ground is very uneven, being strown with huge stones and masses of volcanic rock, and it sounds hollow under the tramp of the foot.
Towards the centre of the plain is a much deeper depression. Those who have ventured to approach it, and look down, describe it as an awful gulf, about eight hundred feet in depth, and presenting a most gloomy and dismal aspect. The bottom is covered with molten lava, forming a great lake of fire, which is continually boiling violently, and whose fiery billows exhibit a wild terrific appearance. The shape of the lake resembles the crescent moon; its length is estimated at about two miles, and its greatest breadth at about one mile. It has numerous conical islands scattered round the edge, or in the lake itself, each of them being a little subordinate crater. Some of them are continually sending out columns of gray vapour; while from a few others shoots up what resembles flame. It is, probably, only the bright glare of the lava they contain, reflected upwards. Several of these conical islands are always belching forth from their mouths glowing streams of lava, which roll in fiery torrents down their black and rugged sides into the boiling lake below. They are said sometimes to throw up jets of lava to the height of upwards of sixty feet. The foregoing woodcut can convey only an imperfect idea of this immense crater.
[Illustration: Crater of Kilauea]
The outer margin of the gulf all round is nearly perpendicular. The height of the bounding cliffs is estimated at about four hundred feet above a black horizontal ledge of hardened lava, which completely encircles it, and beyond which there is a gradual slope down into the burning lake. The surface of the molten lava is at present between three and four hundred feet below this horizontal ledge; but the lava is said sometimes to rise quite up to this level, and to force its way out by forming an opening in the side of the mountain, whence it flows down to the sea. An eruption of this kind took place in 1859. On one side of the margin of the lake there is a long pale yellow streak formed by a bank of sulphur. The faces of the rocks composing the outer walls of the crater have a pale ashy gray appearance, supposed to be due to the action of the sulphurous vapours. The surface of the plain itself is much rent by fissures. It is said that the glare from the molten lava in the lake is so great as to form rainbows on the passing rain-clouds.
The entire Island of Hawaii is of volcanic origin; and besides this great crater it contains two other lofty mountains, whose summits are covered with snow, and whose height is estimated at fifteen or sixteen thousand feet above the level of the sea. The one is named Mouna-Kaah or Keah, the other is Mouna-Loa—the same on whose lower flanks the crater of Kilauea is situated. Mouna-Kaah has long been in a state of repose. So also was Mouna-Loa up to 1840, when it burst forth with great fury, and it has continued more or less in a state of activity ever since. There has been a grand eruption very lately, said by the natives to have been the greatest of any on record.
A new crater opened near the top, at a height of about ten thousand feet, and for three days a flood of lava poured down the north-eastern slope. After a pause of about thirty-six hours, there was opened on the eastern slope, about half way down the mountain, another crater, whence there rose an immense jet of liquid lava, which attained a height of about a thousand feet, and had a diameter of about a hundred feet. This jet was sustained for twenty days and nights; but during that time its height varied from the extreme limit of a thousand, down to about a hundred feet. The play of this fiery fountain was accompanied by explosions so loud as to be heard at the distance of forty miles. Nothing could surpass the awful grandeur of this jet, which was at a white heat when it issued from its source, but, cooling as it ascended into the air, it became of a bright blood red, which, as the liquid fell, deepened into crimson.
In a few days there was raised around this crater a cone of about three hundred feet in height, composed of the looser materials thrown out along with the lava. This cone continued to glow with intense heat, throwing out occasional flashes. The base of this cone eventually acquired a circumference of about a mile. But the fountain itself formed a river of glowing lava, which rushed and bounded with the speed of a torrent down the sides of the mountain, filling up ravines and dashing over precipices, until it reached the forests at the foot of the volcano. These burst into flames at the approach of the fiery torrent, sending up volumes of smoke and steam high into the air. The light from the burning forests and the lava together was so intense as to turn night into day, and was seen by mariners at a distance of nearly two hundred miles.
During the day the air throughout a vast extent was filled with a murky haze, through which the sun showed only a pallid glimmer. Smoke, steam, ashes, and cinders were tossed into the air and whirled about by fierce winds—sometimes spreading out like a fan, but every moment changing both their form and colour. The stream of lava from the fountain flowed to a distance of about thirty-five miles. The scene was altogether terrific—the fierce red glare of the lava—the flames from the burning trees—the great volumes of smoke and steam—the loud underground explosions and thunderings,—all combined to overpower the senses, and fill the mind with indescribable awe.
A remarkable volcanic chain runs along the northern and western margins of the Pacific Ocean. It embraces the Aleutian Islands, the peninsula of Kamtschatka, the Kurile, the Japanese, and the Philippine Islands. The most interesting are the volcanoes of Kamtschatka, in which there is an oft-renewed struggle between opposing forces—the snow and glaciers predominating for a while, to be in their turn overpowered by torrents of liquid fire.
Atolls, or Coral Islands—Their strange Appearance—TheirConnexion with Volcanoes—Their Mode of Formation—AntarcticVolcanoes—Diatomaceous Deposits
To the southward of the Sandwich Islands, on the other side of the equator, there is a large group of islands in the Pacific, which have a very peculiar appearance. They are called Atolls or Coral Islands. Although not exactly of volcanic origin, yet the manner in which they are formed has some connexion with submarine volcanic action.
An atoll consists essentially of a ring of coral rocks but little elevated above the level of the sea, and having in its centre a lagoon or salt-water lake, which generally communicates by a deep narrow channel with the sea. The ring of rocks is flat on the surface, which is composed of friable soil, and sustains a luxuriant vegetation, chiefly of cocoa-nut palms. It is seldom more than half a mile in breadth between the sea and lagoon, sometimes only three or four hundred yards. The outer margin of the ring is the highest, and it slopes gradually down towards the lagoon; but on the outside of the ledge of rocks is a beach of dazzling whiteness, composed of powdered and broken coral and shells. The appearance they present is thus not less beautiful than singular. Some of these islands are of large size, from thirty to fifty miles long, and from twenty to thirty broad, but they are in general considerably smaller. Their most frequent form is either round or oval. The rocks composing them are all formed by different species of coral. The animal which constructs them is of the polyp tribe, and so small that it can be seen only under the higher powers of the microscope. It multiplies by means of buds like those of a tree, the individuals all combining to form a composite stony mass, which is called a polypidom. A number of such polypidoms growing close together form a coral reef. See woodcuts.
[Illustration: Coral]
[Illustration: Coral Polyp]
It was at one time supposed that these coral reefs were erected on the edges of the craters of submarine volcanoes, an opinion to which their annular form, and the lagoon in the centre, lent some countenance; but the vast size of some of them, united to several other particulars connected with them, threw great doubts over this supposition.
More recently it has been shown by Mr. Darwin that, while volcanic agency does perform a part in their formation, it is different from what had been formerly imagined. His supposition is, that these coral reefs were built round the coasts of islands which had once stood very much higher above water than they do now. He conceives that the bottom of the sea under them being very volcanic, and containing large collections of molten lava beneath a thin solid crust, the islands have gradually sunk down into the lava, until their central parts have become covered with a considerable depth of water. The central parts thus submerged, he imagines, form the lagoons in the middle of the islands, while the ring of coral reefs has gradually grown upwards, as the ground on which it rested sank downwards.
[Illustration: Coral Reef.]
The corals thus rise to near the surface, but immediately on their being uncovered by the water they die, and the reef ceases to grow. Then the waves by their action break the upper part of it into pieces, which thus become heaped up by degrees on the remainder, until the mass attain so great a height that the sea can no longer wash over it. Thus the curious ring of land is gradually formed, and affords a nutritive soil, in which cocoa-nuts, on being cast ashore, germinate and grow to be large trees. Other seeds, wafted by the waves or carried by birds, also begin to grow, until the whole surface becomes covered with vegetation. Then comes man and builds his habitation upon those fertile spots, and finds in them an agreeable and convenient abode, well suited to those who are accustomed to live by fishing and other simple means.
You will thus perceive that the connexion between the atoll and the volcano consists in this—that while the coral builds up the reef, the volcano beneath ingulfs the island and causes it to sink down. In some instances, however, the volcano, after a while, reverses its action, and raises up the island with the reef upon it. In such cases, the coral reefs are seen standing out of the water, forming perpendicular cliffs several hundred feet in height. Then also the interior of the island becomes once more dry land, and that, too, of great fertility.
[Illustration: Mount Erebus.]
Almost due south of that region, in the Pacific, where the coral islands abound, but at a great distance from them, and considerably within the limits of the Antarctic zone, lies South Victoria. Here, in lat. 76 degrees S., Captain Ross discovered, in 1841, two volcanoes, which he called Erebus and Terror, after the names of his two ships. Of the former, which is the higher of the two, a view is given in the annexed woodcut. It is covered with perpetual snow from the bottom even to the tip of the summit. Nevertheless, it is continually sending forth vast columns of vapour, which glow with the reflection of the white hot lava beneath. These vapours ascend to a great height, more than two thousand feet above the top of the cone, which is itself twelve thousand feet above the level of the sea.
There is found in these frozen regions a remarkable botanical curiosity, having a certain connexion with volcanoes. The waters of the ocean, all along the borders of the icy barrier, produce in amazing abundance the family of water-plants named Diatomaceae. The Diatoms are so called from their faculty of multiplying themselves indefinitely by splitting into two; and so rapidly is this process performed, that in a month a single diatom may produce a thousand millions. The quantity found in the Antarctic regions is so immense that, between the parallels of 60 degrees and 80 degrees of south latitude, they stain the whole surface of the sea of a pale olive-brown tint. These plants, which are so minute as to be individually invisible, save under the higher powers of the microscope, have the curious property of encrusting themselves with a sheath, or shell, of pure silica. These shells remain after the death of the plant, and are as indestructible as flint. They are marvellous objects, both as respects the elegance of their forms and the beauty of their markings. So great is the accumulation of these shells at the bottom of the sea, that they have formed an immense bank 400 miles in length by 120 in breadth, between the 76th and 78th degrees of south latitude. One portion of this bank rests on the coast at the foot of Mount Erebus.
Now, it is remarkable that these microscopic shells of Diatoms are not unfrequently found in the ejections of volcanoes; while it is generally supposed that, in the case of those situated near the sea, eruptions are caused by the formation of explosive steam consequent on the access of sea-water to the reservoirs of molten lava lying underground. The proximity of this Diatomaceous bed to Mount Erebus would easily explain how these minute shells might be found abundant in the fine dust ejected from that volcano.
Volcanoes of Java—Papandayang—Mountain Ingulfed—Great Destruction of Life and Property—Galoen-gong—Destructive Eruption—Mount Merapia—Great Eruption, with Hurricane—Another, very destructive—Mud Volcano Crater of Tankuban-Prahu—Island of Sumbáwa—Volcano of Tomboro—Terrific Eruption—Timor—A Volcano quenches itself—Cleaving of Mount Machian—Sangir—Destructive Eruption—Bourbon.
One of the most marvellous volcanic regions in the world is that composed of the islands of the Malayan Archipelago in the Indian Ocean. They form a chain stretching from east to west, but curving up towards the north at the western extremity. The most easterly of the chain is Timor, the most westerly Sumatra.
The most interesting of the group is Java, which is almost entirely of volcanic origin, and contains no less than thirty-eight mountains of that conical form which indicates their having at one time or other been active volcanoes. Only a few of them, however, have been in activity in more recent times. The most remarkable eruption was that of the mountain named Papandayang, which occurred in 1772. During this convulsion the greater part of the mountain, which was formerly one of the largest in the island, was completely swallowed up in some great underground gulf.
On the night between the 11th and 12th of August of that year, the mountain appeared to be wholly enveloped in a remarkable luminous cloud. The inhabitants fled in consternation; but before they could all escape, the mountain began to totter, and the greater part of it tumbled down and disappeared. The crash with which it fell was dreadful, the noise resembling the discharge of volleys of artillery. Besides that part of the mountain which thus fell in, a large extent of ground in its neighbourhood was ingulfed. The space measured fifteen miles in length and six in breadth. The ground for many miles round this space was covered with immense quantities of ashes, stones, cinders, and other substances thrown out by the volcano. These were, on many parts of the surface, accumulated to the height of three feet; and even at the end of six weeks, the layers thus deposited retained so much heat as to render the mountain inaccessible. By this dreadful occurrence forty villages were destroyed, some ingulfed with the ground on which they stood, others buried under the loose materials which had been ejected. Not far short of three thousand of the inhabitants perished.
Another of the volcanoes of Java, called Galoen-gong, burst into eruption in 1822, commencing with a terrible explosion of stones, ashes, &c., followed by a stream of hot mud, which overspread a large tract of ground. This eruption proved still more fatal to human life, about four thousand persons having been destroyed.
So lately as September 1849, Mount Merapia, another volcano in this island, which had been supposed to be quite extinct, burst forth into an eruption, which lasted three days. It was accompanied by a violent hurricane. The bed of a river was filled up by the matter thrown out from the crater, and the destruction of property in crops, &c., was immense. Fortunately the inhabitants succeeded in making their escape, so that no lives were lost. A second eruption of this mountain however, in January 1864, was more disastrous, three hundred and fifty people having perished.
Java likewise contains a remarkable mud volcano. When viewed from a distance, there are seen to rise from it large volumes of vapour, like the spray from the billows dashing against a rocky shore, and there is heard a loud noise like distant thunder. On a nearer approach, the source of these phenomena is seen to be a hemispherical mound of black earth mixed with water, about sixteen feet in diameter, and which at intervals of a few seconds is pushed upwards by a force acting from beneath to a height of between twenty and thirty feet. It then suddenly explodes with a loud noise, scattering in every direction a quantity of black mud, which has a strong pungent smell resembling that of coal-tar, and is considerably warmer than the air. With the mud thus thrown out there has been formed around the mound a large perfectly level and nearly circular plain, about half a mile in circumference. The water mixed with the mud is salt, and the salt is separated from it by evaporation for economical purposes. During the rainy season the action of this mud volcano becomes more violent, the explosions are louder, and the mud is thrown to a greater height.
The crater of Tangkuban-Prahu, another of the volcanoes of Java, presents a remarkable appearance. On approaching its edge, nothing is seen but an abyss, from which dense clouds of vapour continually arise, with hideous sounds, like the steam rushing from the open valves of hundreds of steam-engines. This great abyss consists really of two craters, separated the one from the other by a narrow ridge of rock, to which it is possible to descend and view them both. Each of them is elliptical in form, and surrounded by a crater-wall. That of the western, which the natives call the poison-crater, is a rapid slope nearly a thousand feet in depth, and is densely covered with brushwood almost to the bottom. The flat floor of this deep basin is continually sending out vapours, and in its centre is a pool of boiling water of a sulphur yellow colour. The floor itself is nothing but a crust of sulphur full of rents and holes, whence vapours constantly arise. This crust covers a surface of boiling hot bitter water, and by breaking it beautiful crystals of sulphur may be obtained.
The eastern is called by the natives the king's-crater; its walls are only between five and six hundred feet in depth, and are perfectly bare from top to bottom. The surfaces of the rocks composing them are grayish white, an effect produced upon them by the action of the vapours, to which they are continually exposed. The bottom of this crater consists of mud mixed with sulphur; but round the edges are some stones and hard masses. These are the remnants of an eruption which took place from this crater in 1846, when there was thrown up a great mass of sulphurous boiling mud, accompanied by quantities of sand and stones. This mountain, therefore, seems to be also more of the nature of a mud volcano, than of one which throws out burning lava.
Nearly in a right line to the eastward of Java lies the Island of Sumbáwa, in which stands the volcano of Tomboro, the most violent in its eruptions of any in the world. One of the most remarkable occurred in the year 1815, beginning on the 5th of April and continuing till the middle of July. Its effects were felt over an immense tract of country, embracing the Molucca Islands, Java, and portions of Celebes, Sumatra, and Borneo. The concussions produced by its explosions were sensible at a distance of a thousand miles all round; and their sound is said to have been heard even at so great a distance as seventeen hundred miles. In Java the day was darkened by clouds of ashes, thrown from the mountain to that great distance (three hundred miles), and the houses, streets, and fields, were covered to the depth of several inches with the ashes that fell from the air. So great was the quantity of ashes ejected, that the roofs of houses forty miles distant from the volcano were broken in by their weight. The effects of the eruption extended even to the western coasts of Sumatra, where masses of pumice were seen floating on the surface of the sea, several feet in thickness and many miles in extent.
From the crater itself there were seen to ascend three fiery columns, which, after soaring to a great height, appeared to unite in a confused manner at their tops. Ere long, the whole of the side of the mountain next the village of Sang'ir seemed like one vast body of liquid fire. The glare was terrific, until towards evening, when it became partly obscured by the vast quantities of dust, ashes, stones, and cinders thrown up from the crater. Between nine and ten o'clock at night the ashes and stones began to fall upon the village of Sang'ir, and all round the neighbourhood of the mountain. Then arose a dreadful whirlwind, which blew down nearly every house in the village, tossing the roofs and lighter parts high into the air. In the neighbouring sea-port the effects were even more violent, the largest trees having been torn up by the roots and whirled aloft. Before such a furious tempest no living thing could stand. Men, horses, and cattle were whirled into the air like so much chaff, and then dashed violently down on the ground. The sea rose nearly twelve feet above the highest tide-mark, sweeping away houses, trees, everything within its reach.
This whirlwind lasted about an hour, and then commenced the awful internal thunderings of the mountain. These continued with scarcely any intermission until the 11th of July, when they became more moderate, the intervals between them gradually increasing till the 15th of July, when they ceased. Almost all the villages for a long distance round the mountain were destroyed; and it is computed that nearly twelve thousand persons perished. By far the greatest part of this destruction was wrought by the violence of the whirlwind which accompanied the eruption.
Considerably to the eastward of Sumbáwa lies the Island of Timor, in which there was for a long time a volcanic peak, whose perpetual fires served as a lighthouse to mariners navigating those seas. But in the year 1637 there took place a great eruption of the mountain, which ended in its being gobbled up whole and entire, leaving nothing behind it but a lake, in which its fires were quenched, and which now occupies its place.
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 glass.
Mud and Air Volcanoes—Luss—Macaluba—Taman—Korabetoff—NewIsland in the Sea of Azof—Jokmali—Fires of Baku—Mud Volcano inFlank 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 quantities, 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 assemblage 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 masses 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.
[Illustration: 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. Quantities of this mineral oil are frequently found floating on the sea, along the neighbouring shores, 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 Parsees, or fire-worshippers, 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.