PEALE.] 



LOWER GEYSEB BASIN^ — THUD GROUP. 



147 



No. 10. Round Spring.— This spring has never befbre been described. 

 It lias a globular basin about 5 feet in diameter, which is lined with green- 

 ish-brown deposit with a white orifice at the bottom. Itis a quiet spring 

 with a temperature of 140° F. I^ear it are several holes in the deposit, 

 which mark the sites of springs that are now extinct. 



Almost all the springs of this group have what may be termed globu- 

 lar basins, i. e., basins which widen below the surface, having overhang- 

 ing edges, and narrow again to fissures or tube-like orifices. Kone of 

 them are at the boiling point, and all except No. 10 belong to the class 

 of constantly agitated springs, although all have probably periods of 

 increased activity, as noted in two of them. It is doubtful if any are 

 real geysers, as the deposits surrounding them do not present any of 

 the characters seen about the known geysers. The following table 

 compares the temperatures of the three years in which I recorded them : 





1871. 



J872. 





187a 



No. 











Spring. 



Air, 



Spring. 



Air. 



Spring. 



Aiiv 





op. 



jP. 



°F. 



o jr. 



o J». 



O JI. 



1 



187 



55 to 60 



186 



62 



174 



39 



2 



195 



55 to 60 



188 



64 



186 



39 



2c. 





55 to 60 



182 



64 



181 



39 



3 



185 



55 to 60 



162 



64 



165 



89 



Sa. 





55 to 60 



190 



64 



190 



39 



4 



192 



55 to 60 



192 



62 



187 



39 



5 



196 55 to 60 



194 



64 



189 



39 



Ooney 



195 55 to 60 



190 



64 



186 



39 



6 



196 



55 to 60 



184 to 190 



64 



177 



39 



7 





55 to 60 



192 to 195 



64 



190 



39 



8 



192 



55 to 60 



188 



64 



190 



39 



9 



175 



56 to 60 



171 



62 



165 



39 



I am not of the opinion that the temperature of the air has much to 

 do with the variations in temi)eratures of the springs, although the 

 hygroraetrio condition of the atmosphere may slightly affe^it the sur- 

 face temperatures, especially in very large pools. 



In the table above, the differences are probably due mainly to differ- 

 ences in the intensity of activity, and a degree or so may possibly be 

 due to the differences in the thermometers. 



THIRD OR FOUISTTAIN GROUP. 



This is probably the most important group in the Lower Geyser Ba- 

 sin, as it contains more active geysers than any other group, one of 

 them, The Fountain Geyser, being almost equal to the Great Fountain. 

 It also contains the Mud Puffs, one of the most remarkable and beauti- 

 ful mud basins within the limits of the National Park. 



The mound of siliceous deposits on which the Fountain Geyser is sit- 

 uated is conspicuous from most parts of the Basin. The springs on 

 it are Nos. 7 to 15, and of these four are true geysers, while others are 

 spouting vSjirings. Below the geyser mound or plateau is a Avide, fiat 

 area on which the drainage from the Fountain and the adjacent 

 springs spreads out. There are several large basins on this lower level 

 besides many small springs and steam jets. 



The Mud Puffs are on a higher level than tlie Fountain, from which 

 it is separated by a growth of low, scrubby pines. In this area there 

 are evidences of the former existence of springs and geysers. 



