VOLCANOES. One of the striking features of the Andes is its great number of active and extinct volcanoes. Probably not over sixty are now known to be active, but the extinct ones are numbered by hundreds, and have played a very important part, though a secondary one, in cre ating the present conformation of the mountain system. Three principal centres of volcanic ac tivity are recognized; one in the Andes of the north, in Colombia and Ecuador, extending in latitude from 5° N. to 3° S.; a second in Peru, Bolivia, and northern Chile, extending in lati tude from 15° to 28° S.; and a third in central Chile, extending from 32° to 40° S. The highest peaks of the Andes are of volcanic formation, and their peculiar conical forms are distinctive features of the Andean landscape. Many of the most prominent and highest ones have been men tioned; it remains to speak of those which are now active, or which have been active within historic times, and briefly describe their erup tions.
The northern group, mainly comprised in Ecuador, is the most imposing collection of ac tive and extinct volcanoes on earth. Of these, Cotopaxi, Tnnguragua, Sangai, and Pichincha have repeatedly been in eruption in historic times, hut most, if not all, of the others have for a long time been quiescent. The Altar, a truncated mountain, 17,736 feet in height, is said to have once been the highest in the region, hut after a long period of eruption it collapsed within itself. Ruiz, in Colombia, is still smok ing, and Tolima is not quite extinct, but as late as 1S29 was in eruption. In 1849 Purace, in southern Colombia, suddenly exploded, flooding the neighboring country, and covering it with ashes. A similar eruption took place in 1869. Imbabura, in Ecuador, is said to have discharged a deluge of mud and water at the time of the great earthquake in l8118. Antisana is reported as having been in eruption in 1590, and even now sulphurous fumes arise from it,. Cotopaxi,
always smoking, has been repeatedly in eruption, although its great eruptions have occurred at intervals of centuries. Thy last one was in 1877. Tunguragua also is active at irregular intervals, the latest eruption being in 1886. Sangai sends off steam constantly with tremen dous force and noise. Pichincha has, since its eruption in 1660, given off nothing but steam and a little ashes.
The middle volcanic group is found in both the eastern and western Cordilleras; in Peru it includes Sarasara, Atchatayhua, Corupumt, Am pato, Chachani, and Misti, all now quiescent. Oma te and Tutupaca have been in eruption in historic times; indeed, the former was one of the most active in Peru. In Bolivia are Mount Sorata, or Illampu, Sajama, Aucaquileha. Cha ehacomani, Iluiana, Caeaca, Mesada, and DB mani, while in northern Chile are many volcanic cones, !Mine of great height; among them are Taeora, 19,750 feet, Chipieani, Pomerape, Periu aeota. lquima, 20,275 feet, and Toroni, 21,340 feet!, all in the western range. ln the eastern range are Tuachela. Olca, Mino, and Magna, all smoking or emitting lava. South of 011agua are at least thirty extinct volcanoes, exceeding 16,500 feet in height; among them are A utopalla, 20,920 feet, Socompa, 19,620 feet, and Llullail laco, 21.670 feet.
In the central Chilean region are Tupungato, San Jose, Maipo, Tinguiririca, all supposed to be extinct. Las Damas and Peteroa are said to have been in eruption in the last century. The volcanoes grouped about Descabezado are qui escent, though appearances indicate recent erup tion. Chilean ranges contain several vents, from which lava and ashes have been ejected in recent years. Autuco also has had eruptions within historic times. Farther south, Arilintim volcano has frequently been seen in eruption. In all probability, other active volcanoes exist in the fiord region of South Chile, although none has yet been reported.