RECENT WORK ON VOLCANOES 



By E. H. L. SCHWARZ, F.G.S., 



Professor of Geology, Rhodes University College, Grahams town, S. Africa 



The volcanic regions of the globe have long been known and 

 most volcanoes have been described in detail, so that it is to 

 be expected that a certain definiteness would have been reached 

 as to the nature of volcanism. As to the cause, that is another 

 matter — but just what volcanoes are and what happens when 

 they become active, surely that ought to have been settled 

 now beyond question. This is not the case. The investigations 

 into the West Indian eruptions of 1902 threw a flood of light 

 on the subject, in which, however, there are still many lacunae. 

 Dr. Albert Brun's daring work in Java and elsewhere has 

 opened up an entirely new chapter, whilst Reek's work in 

 Iceland and Russell's on the Snake River Plains of Idaho 

 has so largely increased our knowledge that it can hardly be 

 maintained that we have really known anything about the 

 subject of volcanoes till quite recently. I propose in this 

 article to review this recent work briefly, confining myself 

 to actual observations in the field or the laboratory, and 

 picking out only those points which are fundamentally new. 



I will begin with the West Indian eruptions, more especially 

 dealing with Mont Pelee. I need not enter into general details, 

 as these have been so adequately described by Lacroix (1), 

 Flett (2), Anderson (2), Russell (3), and Heilprin (4), whilst 

 an exceedingly interesting collection of letters from eye- 

 witnesses has been published by Flammarion (5). Mont Pelee, 

 which but once, in 185 1, has been known to show signs of 

 activity and then only by throwing out a harmless shower of 

 ashes, commenced its eruption on April 25, 1902. Excursionists 

 immediately ascended the mountain and found that the bowl- 

 shaped hollow at its summit, called L'Etang Sec, was being 

 filled up with boiling mud from which sulphurous vapours 

 were being given off. Eight days later, ashes were ejected, 

 and on May 5 an aValanche of incandescent mud rushed down 



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