SECONDARY PHENOMENA OF THE WEST INDIAN 

 VOLCANIC ERUPTIONS OF 1902.^ 



A COMPLETE report on the secondary volcanic phenomena of 

 the West Indian eruptions of 1902 should include at least the fol- 

 lowing topics : 



Development of consequent streams upon an initial ash surface. 



Stream deflections by volcanic ejecta. 



Subsidence of coastal plain. 



Elevation of marginal deposits. 



Effect of "tidal" or reflex waves. 



Results of marine erosion. 



Sedimentation of sea deposits. 



Eruption within stream valleys. 



The latter subject has been selected for this paper, leaving the 

 others for later publication. According to some views I should 

 include also as secondary phenomena the earthy flows of detrital 

 matter which have played an important part in the destruction 

 both of life and property, and have been generally reported 

 as "mud flows." I regard them as, in part at least, of primary 

 volcanic origin and think that the "mud flow" which buried 

 the Guerin sugar works on May 5 — two days before the destruc- 

 tion of St. Pierre — was a result of an eruption from the crater of 

 Mount Pelee. After the great eruption of May 7 on St. Vincent, 

 more than half a billion gallons of water had disappeared from 

 the crater lake of La Soufriere, which we found, on reaching the 

 crater's rim on May 31, to have fallen about 800 feet below its 

 former level. The evidence indicates that this volume of water 

 was poured out over the mountain, bearing with it bowlders and 

 " earth." This " earth " was composed of soil washed from slopes, 

 the finer fragments of volcanic ejecta, and comminuted rock 

 which has been commonly referred to as "ash." Mingled with 

 widely varying percentages of water, the mixture was generally 

 termed "mud," and in many instances "lava." In the Mav 6 



' Paper read before the American Association for the Advancement of Science, 

 January 2, 1902. 



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