The Island Of Java Contains More Volcanoes, Active And Extinct,
Than Any Other Known District Of Equal Extent.
They are about
forty-five in number, and many of them exhibit most beautiful
examples of the volcanic cone on a large scale, single or double,
with entire or truncated summits, and averaging 10,000 feet high.
It is now well ascertained that almost all volcanoes have been
slowly built up by the accumulation of matter - mud, ashes, and
lava - ejected by themselves. The openings or craters, however,
frequently shift their position, so that a country may be covered
with a more or less irregular series of hills in chains and
masses, only here and there rising into lofty cones, and yet the
whole may be produced by true volcanic action. In this manner the
greater part of Java has been formed. There has been some
elevation, especially on the south coast, where extensive cliffs
of coral limestone are found; and there may be a substratum of
older stratified rocks; but still essentially Java is volcanic,
and that noble and fertile island - the very garden of the East,
and perhaps upon the whole the richest, the best cultivated, and
the best governed tropical island in the world - owes its very
existence to the same intense volcanic activity which still
occasionally devastates its surface.
The great island of Sumatra exhibits, in proportion to its
extent, a much smaller number of volcanoes, and a considerable
portion of it has probably a non-volcanic origin.
To the eastward, the long string of islands from Java, passing by
the north of Timor and away to Panda, are probably all due to
volcanic action. Timor itself consists of ancient stratified
rocks, but is said to have one volcano near its centre.
Going northward, Amboyna, a part of Bouru, and the west end of
Ceram, the north part of Gilolo, and all the small islands around
it, the northern extremity of Celebes, and the islands of Sian
and Sang-air, are wholly volcanic. The Philippine Archipelago
contains many active and extinct volcanoes, and has probably been
reduced to its present fragmentary condition by subsidences
attending on volcanic action.
All along this great line of volcanoes are to be found more or
less palpable signs of upheaval and depression of land. The range
of islands south of Sumatra, a part of the south coast of Java
and of the islands east of it, the west and east end of Timor,
portions of all the Moluccas, the Ke and Aru Islands, Waigiou,
and the whole south and east of Gilolo, consist in a great
measure of upraised coral-rock, exactly corresponding to that now
forming in the adjacent seas. In many places I have observed the
unaltered surfaces of the elevated reefs, with great masses of
coral standing up in their natural position, and hundreds of
shells so fresh-looking that it was hard to believe that they had
been more than a few years out of the water; and, in fact, it is
very probable that such changes have occurred within a few
centuries.
The united lengths of these volcanic belts is about ninety
degrees, or one-fourth of the entire circumference of the globe.
Their width is about fifty miles; but, for a space of two hundred
miles on each side of them, evidences of subterranean action are
to be found in recently elevated coral-rock, or in barrier coral-
reefs, indicating recent submergence. In the very centre or focus
of the great curve of volcanoes is placed the large island of
Borneo, in which no sign of recent volcanic action has yet been
observed, and where earthquakes, so characteristic of the
surrounding regions, are entirely unknown. The equally large
island of New Guinea occupies another quiescent area, on which no
sign of volcanic action has yet been discovered. With the
exception of the eastern end of its northern peninsula, the large
and curiously-shaped island of Celebes is also entirely free from
volcanoes; and there is some reason to believe that the volcanic
portion has once formed a separate island. The Malay Peninsula is
also non-volcanic.
The first and most obvious division of the Archipelago would
therefore be into quiescent and volcanic regions, and it might,
perhaps, be expected that such a division would correspond to
some differences in the character of the vegetation and the forms
of life. This is the case, however, to a very limited extent; and
we shall presently see that, although this development of
subterranean fires is on so vast a scale - has piled up chains of
mountains ten or twelve thousand feet high - has broken up
continents and raised up islands from the ocean - yet it has all
the character of a recent action which has not yet succeeded in
obliterating the traces of a more ancient distribution of land
and water.
Contrasts of Vegetation. - Placed immediately upon the Equator and
surrounded by extensive oceans, it is not surprising that the
various islands of the Archipelago should be almost always
clothed with a forest vegetation from the level of the sea to the
summits of the loftiest mountains. This is the general rule.
Sumatra, New Guinea, Borneo, the Philippines and the Moluccas,
and the uncultivated parts of Java and Celebes, are all forest
countries, except a few small and unimportant tracts, due
perhaps, in some cases, to ancient cultivation or accidental
fires. To this, however, there is one important exception in the
island of Timor and all the smaller islands around it, in which
there is absolutely no forest such as exists in the other
islands, and this character extends in a lesser degree to Flores,
Sumbawa, Lombock, and Bali.
In Timor the most common trees are Eucalypti of several species,
also characteristic of Australia, with sandalwood, acacia, and
other sorts in less abundance. These are scattered over the
country more or less thickly, but, never so as to deserve the
name of a forest. Coarse and scanty grasses grow beneath them on
the more barren hills, and a luxuriant herbage in the moister
localities.
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