212 GEORGE CARROLL CURTIS 



this collection of sand and coarser fragments grows into a 

 pile about the pipe, tending to assume the form of a perfect 

 volcanic fragmental cone with crater falling into the descending 

 pipe, and slopes averaging 25° to 30° (several cones 40 feet in 



Fig. 9. — A secondary (or ash geyser) crater in the Rabaka river trenched by stream. 



Fig. 10. — A secondary cone — ash geyser cone — partially demolished — Ra- 

 baka river. St. Vincent. 



height and 160 feet in diameter were observed on both Marti- 

 nique and St. Vincent). 



The accompanying diagram (Fig. 8) represents the structure 

 of the ash-geyser cone. 



The ash-geyser, indeed, simulates a miniature volcano both 



