Mud and Air Volcanoes--Luss--Macaluba--Taman--Korabetoff--New
Island in the Sea of Azof--Jokmali--Fires of Baku--Mud Volcano in
Flank 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.