208 



GEORGE CARROLL CURTIS 



waters, an eruption which threw its column of steam to a height 

 of over half a mile. I found opportunity to visit the sites of both 

 these explosions on the days following, and to examine them 

 closely. From these and numerous other observations, espe- 

 cially in the Rozeau Dry river of St. Vincent, where the phe- 

 nomena were best developed, it 

 appears that the geyser-like erup- 

 tions may be explained as sec- 

 ondary phenomena. 



Mechanics of ''ash-geyser erup- 

 tions." — The beds of nearly all, if 

 not all, of the rivers which head 

 at the summit craters of La 

 Soufriere and Mount Pelee con- 

 tain deposits of volcanic ejecta 

 generally known as "ash" in 

 depths from a few inches to one 

 hundred feet or more. This frag- 

 FiG. 5.— Small, viscous mud stream mental material ranges from the 

 — 5 feet wide— flowing by pulsations gi^e of a block 22 by 50 by 24 

 in canyon north of Precheau. r , ■ i\ o v 1 • . • 1 



feet m the beche river to impalpa- 

 ble dust. In some instances where the surface is more thickly 

 strewn with bowlders, these rocks have been found to be hot 

 enough to cause cracking of their surfaces, even fumerole-like 

 deposits forming about them. In other places where the stream 

 has deeply intrenched these deposits of volcanic ejecta, it has 

 opened a passage between beds which are hot enough to burn 

 the shoes, and clouds of mingled unconfined steam are given out 

 whenever the hot dust slips into the stream water or the sea. 



The mouths of the Blanche, the Seche, and the Wallibou 

 presented the best examples of these dissected hot-ash beds. 

 When the bed of the stream was dry — its prevailing condition 

 — little indication of this underlying high temperature within 

 the deep stream deposits was apparent, save in the rare instances 

 of hot bowlder surfaces and the mild steaming of the beds from 

 small pits, through which hot vapor was sometimes rising, with 

 the distinct blowing noise of escaping steam. These vents were 



