"The sides of New Bogosloff rise with a gentle slope to the crater. The ascent at first appears easy, but a thin layer of ashes, formed into a crust by the action of rain and moisture, is not strong enough to sustain a man's weight. At every step my feet crushed through the outer covering and I sank at first ankle-deep and later on knee-deep into a soft, almost impalpable dust which arose in clouds and nearly suffocated me. As the summit was reached, the heat of the ashes become almost unbearable, and I was forced to continue the ascent by picking my way over rocks whose surfaces being exposed to the air, were somewhat cooled and afforded a more secure foothold.
"On all sides of the cone there are openings through which steam escaped with more or less energy. I observed from some vents the steam was emitted at regular intervals, while from others it issued with no perceptible intermission. Around each vent there was a thick deposit of sulphur, which gave off suffocating vapors."
[CHAPTER XVI]
DISTRIBUTION OF THE EARTH'S VOLCANOES
Having now considered at some length the principal volcanoes of the earth, and endeavored to obtain some idea of the many wonders they exhibit, especially as regards the vast quantities of material they bring from the inside of the earth, as well as the great force with which they sometimes throw these materials out of their craters, it will be well to point out where such volcanoes are to be found.
It may have seemed to you, when you have carefully followed what has been said about the earth's volcanoes, that they are to be found pretty nearly everywhere, at least so far as latitude is concerned; and in this supposition you are correct; for there are volcanoes in the Arctic Ocean, as in the volcanic island of Jan Mayen between Iceland and Spitzbergen, there are Mt. Erebus and Mt. Terror in the Antarctic Ocean, besides very numerous volcanoes in the Atlantic, Pacific, and Indian Oceans, and their shores in both the temperate and the torrid zones.
There is, however, one thing that you have probably especially noticed and that is that volcanoes are seldom found at very great distances from the ocean, except on some of its arms or seas, such as the Mediterranean Sea. I do not mean by this that all the earth's volcanoes are either situated directly on the coast of the continents or on islands, since, in such a large body as the earth, a distance of a few hundred miles from the ocean is hardly to be regarded as being very far from it. But it is true that all the earth's volcanoes are either situated on the coasts of the continents, or on islands, and, moreover, they are situated to a greater or less extent along lines, which, as we have already pointed out, are believed to mark weak portions of the earth's crust that have been fissured or fractured.
In order that you may have some idea of this distribution, I think it will be well to give you a number of interesting facts that have been pointed out by Dana. According to this authority, there are something in the neighborhood of 300 active volcanoes on the earth. Of these, no less than five-sixths, or 250, lie either on the borders of the Pacific Ocean, or on some of its many islands. Thirty-nine either lie within or on the borders of the Atlantic, of which thirteen are in Iceland, or near the Arctic Circle, three in the Canaries, seven in the Mediterranean Sea, six in the Lesser Antilles, and ten in the Atlantic Oceanic Islands. The Indian Ocean contains only a few active volcanoes. There are, however, a much greater number of extinct volcanoes, which may at any time again become active.
The following is the distribution of the earth's volcanoes as given by Dana. As you will see, from an inspection of [Fig. 24], all of the regions of volcanoes lie either on the borders of the continents, or on islands in the oceans. The districts are as follows: