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.