THE ANTILLEAN VOLCANOES. 279 



clear in the light of what may be called the natural history of vulcan- 

 isni ; for, just as the life history of organic orders and genera is traced 

 only by aid of fossils, so the ontogeny of the volcano may be viewed in 

 the light of the phylogeny traced through its fossil remains — lava 

 sheets, tuff beds, laccolites, volcanic necks like those of the Mount Tay- 

 lor plateau, and other products of organic action during the ages past. 



Naturally the first question concerning the volcano relates to its 

 character; and this is answered partly by such dynamic facts as those 

 recently observed in the Antilles, partly by the static records of the 

 rocks. In the light of the various phenomena, it is convenient to 

 recognize three types of eruption, viz: (1) the Stromboli type, or that 

 of quiet outflow of highly fluent lava; (2) the type of Vesuvius, or that 

 of explosive eruption usually followed by quieter flows of lava ; and 

 (3) the Krakatoa type, represented by violent explosions with little, if 

 any, extravasation of lava. In some measure the types intergrade, the 

 middle one, indeed, approaching the extremes; yet they are so con- 

 nected with the character of the erupted material and other factors as 

 to demand recognition. 



The second inquiry concerning the world's volcanoes relates to 

 geographic distribution; and this is well answered by any convenient 

 map, such as that of Bonney (reproduced in the June number of this 

 journal, page 187), from which it appears that nearly all of the living 

 and recently extinct craters are arranged in lines, or zones, coinciding 

 approximately with continental boundaries. Two of the most striking 

 volcanic belts of the globe are those following the chain of Aleutian 

 islands, and that of the Lesser Antilles from Porto Eico southward 

 to the mouth of Orinoco river; several of the world's largest volcanoes 

 occur in the interlacing zones lying off southeastern Asia; and the 

 world's longest belt begins with the Aleutian chain, follows the coast- 

 wise mountains of western North America, traverses Central America, 

 takes in the great Andean volcanoes of western South America, and 

 stretches thence to Terra del Fuego, if not across to Antarctica to end 

 with Mounts Erebus and Terror. The volcanic belts of the globe are 

 sometimes styled 'lines of weakness' in the earth-crust, though a suffi- 

 cient number of live or recently dead craters lie apart on oceanic 

 islands or in continental interiors to caution conservative geologists 

 against too simple groupings; yet all the facts seem to fall into the 

 generalization that volcanic regions coincide with zones of exceptional 

 activity in continent-making agencies. 



A third inquiry concerning volcanoes relates to their geologic dis- 

 tribution, or — in ultimate analysis — to their connection with other 

 geologic agencies and processes. The observations of numberless geolo- 

 gists in the different countries of the globe seem to answer this inquiry 

 in general terms, by indicating that the agency of vulcanism is deca- 



