PEALE.1 HAYDEN^S VALLEY SPRINGS. 91 



FOREST GROUP.* 



This group of springs is located near tlie right wall of the Grand 

 Canon of the Yellowstone, near its head, and was so named by Profes- 

 sor Comstock, from its being nearly surrounded by timber. The 

 springs were visited by one of our parties in 1871, and a sketch made 

 by the topographer. The position of the springs is indicated on Mr. 

 Holmes's geological map. Most of the springs are situated on a broad 

 flat of sand, mud, and gravel. Mr. Scbonboru's notes give temperatures 

 ranging from 90° up to 190*^. Dr. Heizmann gives a description of 

 these springs as foUows : 



At camp :39, wMcli was opposite the head of the canon, were numerous extinct and 

 active springs, the latter materially aiding in the formation of a clear, rapid stream 

 (70°), which was very acid and astringent, depositing reddish yellow, and running by 

 a great mound-shaped bank containing both the active and extinct springs. Its wa- 

 ter, taken from below all its sources, contained only iron and alumina, sulphates and 

 chlorides. It is formed by several groups of springs about camp 39, closely allied, 

 judging by the great prevalence in all of iron and alum. Two springs in one set 

 north of us (156° and lo8°), each 4 or 5 feet in diameter, muddy, bubbling contents, 

 with no outlet visible, emitting a strong odor of sulphuretted hydrogen, and ejecting 

 with it sulphurous acid gas, contained lime, iron, and alumina, magnesia, sulphates, 

 sulphides, chlorides, and hyposulphites. They are surrounded by countless springs 

 and mud vents of all temperatures. The contents of one of the latter, a very large 

 one, are colored like molasses, and have in agitation a curious, intermittent, thudding 

 sound. Of the others the shades are as various as their temperatures — black, mud and 

 lead, light and deep green, colorless, &c. Six of those with light-green water (88°-100°) 

 having an outlet and very acid, gave only reactions for iron, alumina, magnesia 

 (abundant), sulphates, sulphides (slightly). Two in the same group had water, 

 blackish (deposit drab-green), boiling (170°) and bubbling so violently in deep 

 oblique holes a.s to be thrown out in great waves, slightly acid, and containing iron 

 and alumina, sulphates and sulphides. The sulphur was hardly appreciable after 

 the water was taken out, but together with hyposulphites was deposited in great 

 quantity. 



Another group, separated from the last by a small ridge filled with the remains of 

 sprin>jr8 and apparent geysers, possessed not so many springs, but all of the same 

 kind excepting one (140°), which had a colorless water, more acid than any tested, and 

 contained iron, alumina, sulphates, and sulphides (slightly). All of these springs test- 

 ed emitted sulphuretted hydrogen, (some steam and sulphurous acid gas), the deeper 

 colored the greater quantity, but none evolved carbonic acid gas. The deposits of all 

 contained sUica in various, though small, proportions. 



Professor Comstock, speaking of the group, says : 



This group comprises representatives of all the great classes of thermal springs, 

 including also a variety of cold springs of varying composition and temperature ; 

 "while, as a whole,the locality in which they occur may be said to belong to one of the 

 latest stages of thermal intensity. * * * The majority of the active springs, in- 

 cluding the salses and soUataras, emerge through the enormous accumulations of 

 ancient hot-spring deposits, which here almost completely obscure the underlying 

 beds of volcanic origin. • * * One feature of several of these mud bowls is es- 

 pecially noticeable, ». e., the thickness or toughness of the mud, which causes it to be 

 arranged in the form of low cones about the centers of ebullition. This represents 

 the stage of tansition from the salse proper to the mud puff, but none of the latter 

 were observed in the basin occupied by the Forest Group. 



CRATER HILLS. 



As has been indicated in another portion of the report, the rounded 

 hills which mark this localit}^ were laid down on some of the earlier 

 maps. On Raynolds's map it is called Sulphur Hill. The hills, which 

 were called "Seven Hills" by the Washburn-Doane party in 1870, are 

 composed in part of spring deposits and trachyte tuff. For the geology 

 of this region the reader is referred to Mr. Holmes's report. There 

 are only two hills, instead of seven; one is loO feet in height, and the 

 other about 140 feet. Xo temperatures were taken in 1878, and the fol- 

 lowing description is made up mainly from the reports of 1871 and 1872. 



*Thi8 is the title given by Comstock in Jones's Report, p. 197. 



