SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 66 
It was found that algal growth was everywhere present when the 
temperature of the waters was from 70° to not much above 180° 
Fahrenheit, and that this growth had a marked effect upon the 
Fic. 17—Three of the Seven Sisters Hot Springs above Black Warrior 
Geyser, one mile northeast of Great Fountain Geyser. These springs, although 
very beautiful and each of a different color, are rarely visited by tourists, and 
the same is true of most of the Great Fountain group. Photograph by Walcott. 
amount and character of both caleareous and siliceous deposits. Some 
of these are shown in the accompanying illustrations. 
