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.