VI SYNOPSIS. 



Enumeration of all the active volcanoes in the Cordilleras, p. 285. 

 Relation of the tracts without volcanoes to those abounding in them, 

 p. 296, note 70 at 283 ; volcanoes in the North-west of America, to the 

 north of the parallel of the Rio Gila, pp. 403419 ; review of all the 

 volcanoes not belonging to the New Continent, pp. 285 403 ; Europe, 

 pp. 349350; islands of the Atlantic Ocean, p. 351 ; Africa, p. 354; 

 Asia; Continent, pp. 356 367 ; Thian-shan, pp. 358 359, 433, and 

 notes 42 48; (peninsula of Kamtschatka, pp. 362367); Eastern 

 Asiatic Islands, p. 367; (island of Saghalin, Tarakai or Kara- 

 futo, notes 97 99, p. 305; volcanoes of Japan, p. 373; islands of 

 Southern Asia, pp. 377 382 ;) Java, pp. 298307. The Indian Ocean, 

 pp. 382388 ; the South sea, pp. 388 401. 



Probable number of volcanoes on the globe, and their distribution on the 

 continents and islands pp. 421 431 



Distance of volcanic activity from the sea, pp. 295-6, 432-3. 

 Regions of depression, pp. 431 436 ; Maars, Mine-funnels, pp. 231-3. 

 Different modes in which solid masses may reach the surface 

 from the interior of the earth, through a net-work of fissures in the 

 corrugated soil, without the upheaval or construction of conical or 

 dome-shaped piles, (basalt, phonolite, and some layers of pearl-stone 

 and pumice, seem to owe their appearance above the surface, not to 

 summit-craters, but to the effects of fissures). Even the effusions from 

 volcanic summits do not in some lava-streams consist of a continuous 

 fluidity, but of loose scoriae, and even of a series of ejected blocks and 

 rubbish ; there are ejections of stones which have not all been 

 glowing, pp. 308, 330, 332337, 343347, note 99 (p. 306) note 26 

 (page 335). 



Mineralogical composition of the volcanic rock : generalisation of the 

 term trachyte, p. 452 ; classification of the trachytes, according to 

 their essential ingredients, into six groups or divisions in conformity 

 with the definitions of Gustav Rose; and geographical distributioa of 

 these groups, pp. 453 467 ; The designations andesite and andesine, 

 pp. 452 468, note, 471. Along with the characteristic ingredients of 

 the trachyte-formations there are also unessential ingredients, the 

 abundance or constant absence of which in volcanoes frequently very 

 near each other, deserves great attention, p. 473; Mica, ibid', glassy 

 felspar, p. 474 ; Hornblende and augite, p. 475 ; Leucite, p. 476 ; 

 olivine, p. 477 ; obsidian, and the difference of opinion on the forma- 

 tion of pumice, p. 479 ; subterranean pumice beds, remote from vol- 

 canoes, at Zumbalica in the Cordilleras of Quito, at Huichapa in the 

 Mexican Highland, and at Tschigem in the Caucasus, pp. 340 345. 

 Diversity of the conditions under which the chemical processes of vol- 

 canicity proceed in the formation of the simple minerals and their 

 association into trachytes, pp. 472, 473, 483. 



