INOSSS SMITHSONIAN EXPLORATIONS, IQI5 7 
Fic, 8.—Platform of thin-bedded sinter deposits beneath giant geyser cone, 
Grotto Geyser of Upper Geyser Basin. Photograph by Walcott. 
Fic. 9—Mouth of Great Fountain Geyser showing water at rest just before 
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. 
