362 REACTION OF THE INTERIOR OF THE EARTH 



are the principal volcanic sites. Leopold von Buch enu- 

 merates in the Philippines nineteen lofty isolated conical 

 mountains, all called in the country "Volcanes," but 

 of which some probably are closed trachytic domes. 

 Dana thinks that in the southern part of Luzon there 

 are now only two active volcanoes, Taal in the Laguna 

 de Bongbong or Bombon, with an encircling ridge 

 enclosing a second Laguna (see above, p. 242.) ; and in 

 the south part of the peninsula of Camarines the vol- 

 cano of Albay or Mayon, which the natives call Isaroe ; 

 it is about 3200 feet high, and had great eruptions in 

 the years 1800 and 1814. In the northern part of 

 Luzon granite and mica slate, and even sedimentary 

 formations and coal, are diffused. ( 49 ) 



The long extended group of the Sulu or Solo islands, 

 probably fully a hundred in number, connecting Minda- 

 nao with Borneo, is partly volcanic and partly intersected 

 by coral reefs. Isolated unopened trachytic conical 

 peaks are, indeed, often called "Volcanes" by the 

 Spaniards. 



Dr. Junghuhn, after having carefully passed in re- 

 view all those islands which are to the south of the fifth 

 parallel of north latitude (south, therefore, of the 

 Philippines), and between the meridians of the Nico- 

 bars and the north-west of New Oruinea, states as the 

 result that "in a wreath of islands surrounding the 

 great and almost continental island of Borneo there 

 are 109 lofty fire-emitting mountains and ten mud- 

 volcanoes." This is by no approximate estimate but by 

 actual enumeration. 



In Borneo itself, the Griava Maggiore of Marco 

 Polo ( 491 ), we have as yet no certain knowledge of any 



