THE VOLCANIC MOUNTAINS OF SOUTH AMERICA
The volcanoes of South America are limited to the Andes Mountain
System that stretches like a huge wall along the entire western side
of the continent. The names of the more important of these volcanoes
are marked on the map of South America, shown in Fig. 17. As will be
seen, this huge mountain wall reaches from Patagonia on the south to
the Isthmus of Panama on the north. The arrangement of the volcanoes
in South America is of the linear type. The craters follow one another
in more or less straight lines, or are situated along the lines of
great fissures that lie near the ocean. You must not, however, suppose
that there is a continuous chain of active volcanic mountains from the
Isthmus of Panama to the southern part of the continent. According to
Lyell, from lat. 2° N., or from the north of Quito, to lat. 43° S. or
south of Chile, a total distance including 45° of latitude, there is a
succession of districts with active and extinct volcanoes, or at least
with volcanoes that have been quiet during the last three centuries.
[Illustration: FIG. 17. SOUTH AMERICA]
Lyell traces the volcanoes of South America as follows:
"The principal line of active vents which have been seen in
eruption in the Andes extends from lat. 43° 28' S., ... to
lat. 30° S.; to these thirteen degrees of latitude succeed
more than eight degrees, in which no recent volcanic
eruptions have been observed. We then come to the volcanoes
of Bolivia and Peru, extending six degrees from S. to N.,
or from lat. 21° S. to lat. 15° S. Between the Peruvian
volcanoes and those of Quito another space intervenes of no
less than fourteen degrees of latitude, in which there is
said to be but few active volcanoes as far as is yet known.
The volcanoes of Quito then succeed, beginning about 100
geographical miles south of the equator, and continuing
for about 150 miles north of it, when there occurs another
undisturbed region of more than six degrees of latitude,
after which we arrive at the volcanoes of Guatemala, or
Central America, north of the Isthmus of Panama."
Of course, you must not understand that there are no extinct volcanoes
in these gaps. On the contrary, according to Daubeny, we find,
beginning on the north in the United States of Colombia, the lofty
volcano of Tolima. According to Daubeny's book published in 1848,
Tolima was then constantly emitting steam and sulphur gases from its
summit. Tolima is situated in the easternmost of the three mountain
ranges that extend through this section of the country. It is,
therefore, at a comparatively great distance from the ocean. Tolima
was in eruption in 1595. It again burst out in 1826.
Coming now to Ecuador we find that this, the smallest of the South
American Republics, contains numerous great volcanic mountains.
Some of the principal volcanic mountains are Chimborazo, 20,498 feet
above the sea; Antisana, 18,880 feet; Cotopaxi, 19,660 feet; Pichincha
(17,644 feet in 1848, Daubeny), El Altar, 16,383 feet.
These all lie in South America on the plateau of Quito. As Baron
Alexander von Humboldt has pointed out, the volcanic mountains of
Quito are arranged in two parallel chains that extend side by side
for a distance of over 500 miles north into the State of Colombia,
including between them the high plateaus of Quito and Lacumbia.
According to Whymper, however, who has recently studied this part of
South America, there is a succession of basins between the mountains,
but there is no such thing as a single valley in the interior of
Ecuador. The extinct volcanoes of Cayamba, Antisana, and Chimborazo
are the most important. On all three mountains there are old lava
streams on their sides. Although no craters can be seen on their
summits, yet it is almost certain they once had craters. There is
plenty of room on the summit of Antisana for a cone as great as that
of Cotopaxi. Whymper is of the opinion that the snow domes that form
the summit of Chimborazo were at one time two of the highest points of
the rim of the old crater.
Nearly due south of Quito is the great volcanic cone of El Altar.
Like all the peaks of this high plateau, El Altar rises to a great
height above the sea, being at the present time 16,383 feet above the
sea. This mountain has an enormous crater that appears to be dormant
or extinct, and is covered with snow. According to the traditions of
Indians, El Altar, or, as they call it, _Capac Urcu_ or _The Chief_,
was the highest mountain near the equator, being much higher than
Chimborazo. But during a prodigious eruption that occurred before the
discovery of America, and continued uninterruptedly for eight years,
the height of the mountain was considerably reduced. According to
Boussingault, the fragments of the cone of this celebrated mountain
are now spread for great distances around the mountain on the
surrounding lowlands.
Pichincha in Ecuador, an extinct volcano, is situated almost
immediately on the equator. It has a height as measured by Whymper by
the barometer, of 15,918 feet above the Pacific. The summit is covered
by blocks of pumice. Several species of lichens are found at this
elevation. According to Daubeny, Pichincha was extinct prior to 1539,
when it became active. There were also eruptions in 1577, 1587, and
1668. It was also in activity during 1831.
Cayamba, another volcanic mountain of Ecuador, lies to the east of
Pichincha, a short distance north of the equator. Its height is 19,186
feet. It is nearly extinct.
Cotopaxi, 19,680 feet, is another volcanic mountain of the high
plateau of Quito. Cotopaxi is still active. Its slopes are covered
with snow down to a height of about 14,800 feet. Between the lower
edge of this snow line and the lower slopes of the mountain, there
lies a zone of naked rock.
According to Whymper, the eruption of Cotopaxi, in 1877, was preceded
by an unusual degree of activity in the earlier parts of the year.
This, however, did not cause any alarm until June 25th, 1877, when,
shortly after midday, an eruption, attended by tremendous subterranean
roars, began, and an immense black column shot up into the air for
about twice the height of the cone. This eruption was clearly visible
at Quito, for the wind blew the ashes towards the Pacific. At this
time the summit had not changed its appearance, but towards 6:30
A. M., on the next day, another enormous column of ashes
rose from the crater. The ashes and cinders were first carried due
north by the winds, and then, spreading out in all directions, were
subsequently distributed through the air all over the country. At
Quito, as early as 8 A. M., the sky assumed the appearance it
generally has at twilight, and the darkness increased until midday,
when it became as dark as at midnight. Indeed, it was so dark that one
could not see his hand before his face.
During this eruption, as is very common in the eruptions of the
snow-clad mountains of South America, a flood of water, due to the
rapid melting of the snow and ice on the summit, rushed down the
mountain slopes at 10 o'clock A. M., on the 26th of the
month, almost immediately after the appearance of a stream of lava
that began to flow down the mountain. In a few moments the mountain
was completely shut off from view by immense columns of steam and
smoke. At first, a low, moaning sound was heard, which rapidly
increased to a roar, when a deluge of mud, mingled with huge blocks of
ice and stones, swept down the mountain, leaving a desert in its path.
It is estimated that at some places this stream moved with a velocity
of fifty miles per hour.
The general appearance of Cotopaxi is shown in the accompanying
reproduction from the painting by Frederick E. Church in the Lenox
Library, New York.
According to Whymper, who made an ascent of Cotopaxi in 1880, the
crater on the summit has the form of an immense amphitheatre, 2,300
feet across from north to south, and 1,650 feet from east to west.
Its crest is irregular and notched. The crater is surrounded by
perpendicular cliffs. The western side of the volcano is irregular.
Barometric measurements gave the height of this volcano at 19,498
feet. Its height as taken by La Condamine, during the early parts of
the last century, was 19,605 feet, so that, according to Whymper,
assuming as would seem probable, that this difference in height has
not all been due to errors in measurements, the volcano has grown or
increased in height during the last century and a half.
Chimborazo, 20,498 feet, is another lofty mountain on the plateau of
Quito. This volcano is situated in lat. 1° 30' S., and is not at the
present time in an active condition. It is, however, formed entirely
of volcanic material. Its upper portions are covered with a layer of
snow to a level of some 2,600 feet below the summit.
[Illustration: COTOPAXI _From a Painting by Frederick E.
Church in the Lenox Collection of the New York Public Library. By
Permission_]
Chimborazo has an enormous volcanic summit, which, when seen from the
Pacific, when the air is especially clear after the long rains of
winter, is a most splendid sight. Whymper, who ascended the mountain,
says:
"When the transparency of the air is increased and its
enormous circular summit is seen projected upon the deep
azure of blue of the Equatorial sky, it represents a
magnificent sight. The great rarity of the air through
which the top of the Andes is seen adds much to the
splendor."
Whymper says, that as far as records are concerned, there have been no
eruptions of Chimborazo, which has apparently been an extinct volcano
for many years. Its crater has been completely buried by a thick cap
of ice on its summit, while what lava streams exist on the mountain
are either covered by large glaciers, or have been removed by erosion,
or hidden by vegetation.
Chimborazo possesses less of the conical outline than Cotopaxi. There
are steep cliffs towards the summit that have been named by Whymper
"the northern and southern walls." They seem to him to have been
formed by the violent upheavals of the explosive eruptions that have
blown away portions of the cone.
There are other volcanoes in this district, but the above are all we
have space for describing.
According to Lyell, the volcano of Rancagua, in Chile, lat. 34° 15'
S., is continually throwing up ashes and vapors like Stromboli.
Indeed, a year seldom passes in Chile without some earthquake shocks.
Of these shocks those which came from the side nearest the sea are
most violent. The town of Copiapo was laid waste by these shocks
during the years 1773, 1796, and 1819, in both instances after
intervals of twenty-three years.
Since the volcanic mountains of South America are snow-covered the
occurrences of volcanic eruptions are apt to be attended by great
floods caused by the rapid melting of the snow, as well as sometimes
by the breaking of huge subterranean cavities that are filled with
water.
According to Lyell, the volcanoes of Peru rise from a plateau from
17,000 to 20,000 feet above the sea. One of the principal volcanoes
of Peru is Arequipa, whose summit is 18,877 feet above the level of
the sea. The mountain takes its name from the city of Arequipa, which
is situated not far from its base. It is an active volcano. Another
volcano, Viejo, is found in lat. 16° 55' S.
According to Lyell, there are active vents extending through Chile to
the island of Chiloe to lat. 30° N.
Aconcagua, west of Valparaiso, in lat. 32° 39' S., 23,000 feet in
height, the highest mountain in South America, is still in an active
condition. According to Scrope, when the city of Mendoza was destroyed
by an earthquake, that killed 10,000 people, in March, 1861, it is
probable that Aconcagua was in eruption.
There are many other active volcanoes in Chile, extending as far south
as the volcanoes of Patagonia, north of the Straits of Magellan as
well as others of Tierra del Fuego.