704 DYNAMICAL GEOLOGY. 



mene and other volcanic regions; and, more to the eastward, toward the Caspian, 

 Mount Ararat, 16,950 feet high; Little Ararat, 12,800 feet; Demavend, on the south 

 shore of the Caspian, 20,000 feet, (c.) The Red Sea, along its southern borders, where 

 there are a number of lofty volcanic summits, (d. ) The East Indies, where there are 

 two hundred or more volcanoes, of which there are nearly fifty in Java alone, according 

 to Dr. Junghuhn, and twenty-eight out of the fifty now active; nearly as many in 

 Sumatra; one hundred and nine in the small islands near Borneo; a number in the 

 Philippines, etc. 



4. In the Indian Ocean. — A few in Madagascar; also the Isle of Bourbon, Mauritius, 

 and the Comoro Islands, and, to the south, Kerguele"n Land, etc. 



5. On the Atlantic Borders. — Only in the Bight of Benin, on the African coast, where 

 one in the Cameroons Mountains is said to be 14,000 feet high; and the neighboring 

 islands, from Fernando Po to Annabon. 



6. In the Atlantic Ocean. — St. Helena, the Cape Verdes, Canaries, Madeira, Azores, 

 and Iceland. All the islands of the deep part of the ocean (that is, not on the European 

 or American borders) are volcanic. 



7. Over the Interior of the Continents. — In America, North and South, there are none 

 east of the Rocky Mountains and Andes ; in North America, there are extinct cones at 

 the summit of the Rocky Mountain chain, about the head-waters of the Yellowstone, 

 but none east of its crest range. In Africa, none are known. In Asia, there is a small 

 volcanic region in the Thian-Shan Mountains, at Pe-schan and Turfan, besides hot 

 springs near Alak-tu-kul, and some other spots in that vicinity. In Australia, none 

 are known over the interior, the few observed being situated near its southern border. 



2. Kinds of Volcanic Cones. 



As the volcanic mountain is made from its own ejections, it may 

 consist either (1) of lava alone; (2) of tufa alone; (3) of cinders 

 alone ; (4) of combinations of lavas with either cinders or tufas, or 

 with both. The last is the more common kind. 



1. Lava-cones. — Lavas, when quite liquid, flow off naturally at a 

 small angle. The average slope of lava-cones is, therefore, very gen- 

 tle, — usually between three and eight degrees. 



The great volcanoes of Hawaii (Sandwich or Hawaian Islands), 

 Mount Loa and Mount Kea, shown in the map (Fig. 1109), and sec- 

 tions of which are given in Figure 1108, are mainly lava-cones ; and 



Fig. 1108. 



A, B, B, C, profile of Hawaii, as seen from the eastward ; L, Mount Loa ; K, Mount Kea. 



the general slope is six to eight degrees. (These two figures are parts 

 of one profile view of the island, the two joining at B.) -ZEtna has a 

 similar low inclination. A horizontal section of Mount Loa, 1,800 

 feet below its top, would be nearly twenty miles broad. 



