244 EEPOET UNITED STATES GEOLOGICAL SUEVEY. 



No. 19. In this collection there are about a dozen pots of light-colored 

 mud. 



No. 24. This is a red mud spring in a cave-like hole 6^ feet below the 

 general level. The hole is 21 feet by S to 13 feet, but the spring is only 

 5 by 7^ feet. The water is a thin red mud, which bubbles and splashes 

 against the walls, forming red stalagmitic processes, which are very 

 pretty. In the hole with the spring is a steam hole, at the wider end, 

 surrounded with moss. 



No. 30 is a large, green turbid pool surrounded by numerous mud pots 

 and slimy holes of muddy water. These extend through the space in- 

 tervening between Nos. 30 and 31. 



A number of the springs in the group are boiling and bubbling (Nos, 

 5, 12, 13, 15, 25, and 27), but there are none so far as known that deserve 

 the name of geyser except No. 1. There are many steam vents not 

 enumerated in the table, and some of the more quiet si)rings may have 

 periods of increased activity. Our time was short and occupied mainly 

 in mapping tjie springs, so that we cannot distinguish all the springs 

 that are periodic in their action. 



The table gives the points noted in relation to the springs that have 

 not had special mention here. 



EMEEALD GEOUP. 



This group is situated mainly at the forks of Iron Spring Creek, 1,600 

 yards west of the Castle Geyser and 1,000 yards southwest of the White 

 Pyramid. It is separated from the main groups by a considerable growth 

 of timber, mainly pines. 



On the right-hand branch, 800 feet above the main springs of the 

 group, is a wide marsh, in which there are a number of warm-water 

 pools and several springs. Of the latter three were examined, and the 

 following are the results : 



a. Small white mound, 1 by 2^ feet, with a hard, geyserite edge, in 

 which the water was a foot below the surface and had a temperature of 

 1870 F. 



b. A greenish-yellow lined basin, measuring 7 by 8 feet, in which the 

 water had a temperature of 160° F. 



c. An irregular shaped basin, 20 by 30 feet, in the marsh. As a 

 spring it is nearly extinct, and the temperature was not taken. The 

 marsh had an abundant deposit of ferric oxide. 



I have also included the Black Sand Geyser (or spring, for its title 

 to the name of geyser is not settled) in this group, although it is sepa- 

 rated from the other springs by trees. It does not come in very well 

 with any other group, however, and this appears to be the best place to 

 consider it. 



The Emerald Group is so far from the location of the principal geysers 

 that very little time is usually devoted to it in comparison with the 

 other groups. Of the 15 springs enumerated in the table, no one has 

 been observed to be a first-class geyser. Nos. 1, 2, and 15 are the only 

 ones that afford indications of geyseric action. The group is well worth 

 a visit, however, as the Emerald Spring is remarkable for its beauty, 

 and the Great Hot Basin for its great size, almost rivaling in this par- 

 ticular the large spring of the Egeria Group in the Lower Basin. It is 

 not, however, so remarkable for the brilliancy of its coloring as the latter. 



