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.
For some readers this may be a surprising chapter heading, for it is a general impression that there are no volcanoes in the United States. It is true that practically all of the volcanoes of this country are dormant or extinct. They have, however, at one time been exceedingly active, and, if reports are correct, some of them were active during comparatively recent times.