148 



DYNAMICAL GEOLOGY. 



and geysers. On Gardiner's River the vents are mostly 

 hot carbonated springs, depositing lime ; on Firehole 

 River they are geysers, depositing silica. In Yellowstone 

 Park alone there are in 

 all 3,000 vents, of which 

 sixty-two are eruptive 

 geysers. In the lime 

 carbonate springs the de- 

 posits on hillsides have 

 given rise to a succession 

 of terraces (Fig. 41, page 

 75), and sometimes the 

 water descending 

 through a succes- 

 sion of pools from 

 terrace to terrace 



FIG. 77. Deposits from carbonated springs. 



gives rise to beautiful stalactitic forms (Fig. 77). In 

 the geysers the hot alkaline waters collect in pools, 

 and deposit the silica first in a gelatinous condition, 

 which afterward concretes into all kinds of fantastic forms 

 (Fig. 78). The deposit immediately about the eruptive 



