VOLCANOES. 723 



the mountain. The cinders are thrown upward from the vent, or 

 crater, to a great height, as a jet of sparks or fiery masses, and fall 

 around in cooled particles or fragments, which are simply granulated 

 lava : they may build up a conical elevation around the vent, or be 

 carried to a distance by the winds. 



When rain or moisture from any source descends with the cinders, 

 the mass forms tufa, — a kind of volcanic sandstone or conglomer- 

 ate, being stratified, granular in texture, not very firm, and usually 

 of a gray, yellowish-gray, yellowish-brown, or brownish color. 



2. Geographical Distribution Volcanoes occur (1) over the bor- 

 der-regions of the continents, — that is, the regions between the 

 oceans and the summit of the border-range of mountains, as between 

 the Pacific and the eastern limit of the summits of the Rocky Moun- 

 tains ; (2) in the continental islands, or those near sea-coasts ; (3) in 

 oceanic islands, nearly all of which, excepting a few of very large size 

 and the coral islands, are throughout volcanic, — and the coral islands 

 have probably a volcanic basis. (4) Volcanoes are most numerous 

 along the borders of the larger ocean, the Pacific, — the mainland, or 

 the islands near by, abounding in them on the east, north, and west, 

 and, to some extent, on the south in the Antarctic seas. (5) They are 

 numerous also in the seas separating the northern from the southern 

 continents, namely, the West Indies, between North and South Amer- 

 ica ; the Mediterranean, between Europe and Africa ; the Red Sea, 

 between Asia and Africa ; the East Indies, between Asia and Austra- 

 lia, — the whole together making a transverse volcanic belt around the 

 globe. Few exist about the Atlantic, excepting those of the islands. 

 Over the interior of continents, remote from the regions mentioned, 

 they are almost unknown ; the Thian Shan region in Central Asia is 

 one of the very few. 



( 6.) Volcanoes are very commonly in linear series or groups. 



1. Borders of the Pacific. — About the Pacific, volcanoes occur in Fuegia, the south- 

 ern extremity of the Ancles; in Patagonia; thirty-two in Chili, — that of Aconcagua, 

 23,000 feet high; seven or eight in Bolivia and southern Peru. — Arequipa, 18,877 feet; 

 nineteen or twenty about Quito, nearly all over 14,000 feet, and among them Cotopaxi, 

 19,660 feet in altitude (by barometer, Dr. Reiss, in 1873); in Central America, thirty- 

 nine; in Mexico, seven of large size, with others smaller; in California, Oregon, and 

 northwest America, twelve, making a lofty series of snowy summits, 11,000 to 14,000 

 feet high, — St. Helen's, in Oregon, probably 12,600 feet; Mount Hood, 11,225; Mount 

 Shasta, 14.440. In the Aleutian Islands, which form a curve like a festoon, across the 

 Northern Pacific, there are twenty-one islands with volcanoes ; in Kamtchatka, fifteen 

 to twenty; in the Kuriles, thirteen; in the Japan group, twenty-four, some 10,000 feet 

 high; in the Philippines, fifteen to twenty; several along the north coast of New 

 Guinea; a number in New Zealand; in the Antartic, on the parallel of 76° 5', and near 

 the meridian of 168° E., Mounts Erebus and Terror, 12,400 and 10,900 feet high, both 

 in full action when seen by Ross, in 1841 ; and, more to the east, south of Cape Horn, 

 Deception Island and Bridgman's. 



