PRESENT CHANGES IN THE EARTH. 



119 





Fig. 45. 



by the winds blowing upon the descending spray. Wood 

 is often found in the neighborhood petrified from this 

 caused 



204. Explanation. The action of the geyser is inter- 

 mittent, and its explanation has been thus given by Ly- 

 ell : " Suppose water percolating from the surface of the 

 earth to penetrate into the subterranean cavity A D 

 (Fig. 46, p. 120) by the fissures F F, while at the same 

 time steam at an extremely high temperature, such as is 

 commonly given out from the vents of lava currents 

 during their solidification, emanates from the fissures C 



