DISCUSSION AS TO ORIGIN 281 



. . . "A good illustration of this relationship between sudden movements of 

 rock folds and displays of volcanic activity is to be found in the history of the vol- 

 canic eruptions in the West Indies and the large earthquakes which have occurred 

 in the West Indies or in adjacent countries. As soon as a fracture occurs pressure 

 is relieved, the deep hot rocks become fluid and are forced up the fissures by the 

 weight of the crust." 



Unfortunately for this theory, there is absolutely no indorsement in 

 nature to its basic proposition that " nearly all active volcanoes occur 

 along the ridges or rock folds which are in the vicinity of ocean waters." 



In this connection it is interesting to note that M. de Montessus de 

 Ballare,* from careful field studies reaches a conclusion opposite to those 

 of Milne. He says : 



" It is very remarkable that the distribution of seismic instability in all degrees 

 of intensity presented, in all possible combinations with the presence or absence of 

 volcanoes, in their activity or their extinction, affirms at once a most complete 

 independence in time and space of the two orders of phenomena." 



The fissure theory has also been directly applied to Pele by Jaggar f 

 as follows : 



"A slip of some sort liberated a steam column; the cause of the fracture or the 

 source of the steam is one step too far back into the theory to venture to treat it 

 here. Release once started followed old vents, water holes, and these vents were 

 Soufriere and Pele. The explosion that followed release of pressure tore away the 

 walls of the fissure and its violence ground the material to powder. The material 

 came from a depth where the rocks were hot, and it was heated further by 

 friction." 



INTERIOR THEORY OF VULCAN ISM 



Recent views on the condition of the earth's interior. — Of late years broader 

 thinkers have realized more and more that the problems of the earth's 

 interior could not be interpreted merely by geological study of its sur- 

 face conditions, and that they required the assistance of the laws of 

 chemistry, physics, and mathematics, by which we obtain our knowledge 

 of the sun and other kindred heavenly bodies, of which our planet is 

 one.J Great physicists, like Sir William Thompson, now Lord Kelvin; 

 George Darwin, Newcomb, and others, by mathematical processes grad- 

 ually destroyed the earlier hypotheses concerning a fluid condition of 



* Investigations on the earthquakes in the region of the equatorial Andes. Academie des 

 Sciences, January 11, 1904. 



|T. A. Jaggar : Popular Science Monthly, August, 1902, vol. lxi, p. 365. 



% Major J. W. Powell, while Director of the United States Geological Survey, saw the importance 

 of physical research in connection with the interpretation of the earth's interior, and at one time 

 secured from Congress an appropriation to conduct experiments with high-pressure temperatures 

 under the direction of Dr Carl Barus, now professor of physics at Brown University, but the in- 

 vestigation was too deep and far reaching for the appropriation committee to apprehend. The 

 little work that Professor Barus did, however, before his allotment was expended remains as 

 practically the only American attempt to rationally study the condition of the earth's interior. 



