NO. 3 



SMITHSONIAN EXPLORATIONS, I915 



Fig. 8. — Platform of thin-bedded sinter deposits beneath giant geyser cone, 

 Grotto Geyser of Upper Geyser Basin. Photograph by Walcott. 



Fig. 9. — Mouth of Great I'ountain Geyser showing water ai re.-^l ju>l lielore 

 a great eruption, as seen in Fig. 10. Photograph by Walcott. Alternate 

 wetting and drying of area about the geyser results in deposition of salica in 

 beautiful forms all about its basin. 



