ASIATIC INLAND VOLCANOES
Upon examining further into the distribution of the continental
volcanoes, another very interesting fact presents itself. The volcanoes
are in almost every instance situated either close to the coasts of the
continent, or at no great distance from them. There are, indeed, only
two exceptions to this rule. In the great and almost wholly unexplored
table-land lying between Siberia and Tibet four volcanoes are said to
exist, and in the Chinese province of Manchuria several others. More
reliable information is, however, needed concerning these volcanoes.
It is a remarkable circumstance that all the oceanic islands which
are not coral-reefs are composed of volcanic rocks; and many of
these oceanic islands, as well as others lying near the shores of the
continents, contain active volcanoes.
Through the midst of the Atlantic Ocean runs a ridge, which, by the
soundings of the various exploring vessels sent out in recent years, has
been shown to divide the ocean longitudinally into two basins. Upon this
great ridge, and the spurs proceeding from it, rise numerous mountainous
masses, which constitute the well-known Atlantic islands and groups
of islands. All of these are of volcanic origin, and among them are
numerous active volcanoes. The Island of Jan Mayen contains an active
volcano, and Iceland contains thirteen, and not improbably more; the
Azores have six active volcanoes, the Canaries three; while about eight
volcanoes lie off the west coast of Africa.
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