A WALK IN THE YELLOWSTONE PARK. 83 



to a safe distance, when it burst from the orifice with terrific 

 momentum, rising in a column the full size of this immense 

 aperture, to the height of sixty feet; and through and out of 

 the apex of this vast aqueous mass five or six smaller jets or 

 round columns of water, varying from six to fifteen inches in 

 diameter, were projected to the marvelous height of two hun- 

 dred and fifty feet." This eruption continued twenty min- 

 utes; and two eruptions occurred during twenty-four hours. 



The numerous other geysers in their action present phe- 

 nomena essentially similar to these. The mineral deposit gen- 

 erally forms a mound, cone, or nozzle, through which the 

 water escapes. This varies greatly in diameter and height. 

 In the White Dome and White Pyramid geysers it is twenty- 

 five feet high. In the Giant geyser the cone is ten feet high 

 and rests on a platform four feet high and over three hundred 

 feet in diameter. The material is generally geyserite ; but a 

 few geysers and springs exist in which it is travertin or cal- 

 careous tufa, consisting of calcium carbonate. The Soda 

 Butte, on the east of the Yellowstone, is a conical mound 

 twenty feet high, which though now closed at the top, was 

 formerly an active geyser. It is composed of travertin, and 

 Soda Butte is a misnomer. 



The thermal springs of the Park have built up mineral de- 

 posits of extremely curious and interesting character. The 

 Mammoth Hot Springs, on Gardiner's river, three miles from 

 its mouth, situated on a series of terraces, present a fine de- 

 velopment of a style of formation characteristic of hot springs 

 in various parts of the world. The waters issue at many dif- 

 ferent levels along a slope, and the calcareous deposit takes 

 the form of a pile of tubs so arranged that the overflow from 

 one at a higher level falls into another at a lower level. The 

 tubs are of various depths and diameters, and sometimes dis- 

 play lively shades of color greenish, reddish, and yellowish. 

 There are several terraces of deposits from which the water 

 has disappeared ; and the evidence is, generally, that the ther- 

 mal energy of the region is diminishing. 



The phenomena of hot springs are well known in various 



