NO. 3 



SMITHSONIAN EXPLORATIONS, I915 



Fig. 12. — Small geyser and hot spring on bank of Firehole River, showing 

 geyser and hot-sprmg deposit side by side. Small vents on side of spring ernpt 

 quite frequently. Photograph by Walcott. 





Fig. 13. — Sulphur Mountain Geyser boiling, prior to small eruption. Coloring 

 in mouth and throat of geyser varies from rich cream above to deep red and 

 buff below. Minor details of siliceous deposit about area flooded by hot sili- 

 ceous water are most beautiful. Photograph by Walcott. 



