But even of the islands that occupy a prominent place on the map of the world, there is not wanting evidence to show that a large number derive their origin from the action of volcanic power. Among these may be mentioned many of the Molucca and Philippine groups, also several in the Grecian Archipelago, and not a few of the Azores and the Canaries,—in particular the lofty peak of Teneriffe, rising 12,000 feet above the level of the sea. In some cases, indeed, the actual process of their birth, and of their subsequent growth and development, has been minutely observed. A remarkable example occurs among the Aleutian Islands already referred to. In the year 1796 a column of smoke was seen to issue from the sea; then a small black point appeared at the surface of the water; then flames broke out, and other volcanic phenomena were exhibited; then the small black point grew into an island, and the island increased in size until it was at last several thousand feet high, and two or three miles in circumference. And such it remains to the present day.
Fig. 28.—Bird’s-eye view of Santorin during the volcanic eruption of February, 1866. (Lyell.)
a. Therasia.
b. The northern entrance, 1068 feet deep.
c. Thera.
d. Mount St. Elias, rising 1887 feet above the sea.
e. Aspronisi.
f. Little Kaimeni.
g. New Kaimeni.
h. Old Kaimeni.
i. Aphroessa.
k. George.
The neighborhood of Santorin in the Grecian Archipelago has been noted from very remote times as the theatre of submarine eruptions. This island, which is itself to all appearance the crater of a vast volcano, has the form of a crescent, and, with the aid of two smaller islands which stretch across between the horns of the crescent, encloses an almost circular bay. We learn from Pliny that in the year 186 before Christ, within this bay an island rose up which was called Hiera or the Sacred island. It was twice enlarged during the Christian era, once in 726, and again in 1427, and still exists under the name of Palaia Kaimeni, that is to say, the Old Burnt Island. In 1573 a second island made its appearance, and received the name of the Little Burnt Island, Mikra Kaimeni. In 1707 and 1709, a third island was thrown up, and was distinguished from the other two as Nea Kaimeni, the New Burnt Island. Lastly, in 1866 the hidden volcanic power again became active, and two new vents were formed, called respectively Aphroessa and George. “At the end of January,” writes Sir Charles Lyell, “the sea had been observed in a state of ebullition off the southwest coast, and part of the Channel between New and Old Kaimeni, marked seventy fathoms in the Admiralty chart, had become, on February the eleventh, only twelve fathoms deep. According to M. Julius Schmidt, a gradual rising of the bottom went on until a small island made its appearance called afterward Aphroessa. It seems to have consisted of lava pressed upward and outward almost imperceptibly by steam, which was escaping at every pore through the hissing scoriaceous crust. ‘It could be seen,’ says Commander Lindesay Brine, R. N., ‘through the fissures in the cone that the rocks within were red hot, but it was not till later that an eruption began.’ On February the eleventh the village of Vulcano on the southeast coast, where there had been a partial sinking of the ground, was in great part overwhelmed by the materials cast out from a new vent which opened in that neighborhood, and to which the name of George was given, which finally, according to Schmidt, became about two hundred feet high.
“Commander Brine having ascended on February the twenty-eighth, 1866, to the top of the crater of Nea Kaimeni, about three hundred and fifty feet high, looked down upon the new vent then in full activity. The whole of the cone was swaying with an undulating motion to the right and left, and appeared sometimes to swell to nearly double its size and height, to throw out ridges like mountain spurs, till at last a broad chasm appeared across the top of the cone, accompanied by a tremendous roar of steam and the shooting up from the new crater, to the height of from fifty to a hundred feet, of tons of rock and ash mixed with smoke and steam. Some of these which fell on Mikra Kaimeni, at a distance of six hundred yards from the crater, measured thirty cubic feet. This effort over, the ridges slowly subsided, the cone lowered and closed in, and then, after a few minutes of comparative silence, the struggle would begin again with precisely similar sounds, action, and result. Threads of vapor escaping from the old crater of Nea Kaimeni proved that there was a subterranean connection between the new and the old vents. Aphroessa, of which the cone was at length raised to a height of more than sixty feet, was united in August with the main island. This was due in part at least to the upheaval of the bottom of the sea, which is now only seven fathoms deep in the channel dividing the New and Old Kaimenis, whereas in the Admiralty chart the soundings gave a hundred fathoms.”[97]
CHAPTER XVI.
SUBTERRANEAN HEAT—ITS POWERS ILLUSTRATED BY EARTHQUAKES.
Earthquakes and volcanos proceed from the same common cause—Recent earthquakes in New Zealand—Vast tracts of land permanently upraised—Earthquakes of Chili in the present century—Crust of the Earth elevated—Earthquake of Cutch in India, 1819—Remarkable instance of subsidence and upheaval—Earthquake of Calabria, 1783—Earthquake of Lisbon, 1755—Great destruction of life and property—Earthquake of Peru, August, 1868—General scene of ruin and devastation—Great sea wave—A ship with all her crew carried a quarter of a mile inland—Frequency of earthquakes.