A WALK IN THE YELLOWSTONE PAEK. 81 



others have a basis of rich ochre, with the projections of 

 umber brown. In places, the reds are nearly of a dark 

 scarlet. Here the rocks are of a lovely French gray ; there, 

 of a delicate fawn tint, rising above to saffron, and melting to 

 snow-white below ; while in places, patches of vivid green, 

 orange or black mark the masses of moss and lichen fed by 

 the abundant spray, and forced into luxury of growth by the 

 warm streams from the numberless springs issuing from the 

 walls of the canon." Lippincott's Magazine, June, 1880, p. 699. 



It is not for the scenery not even for the geology of the 

 Park, that I have led you hither. What I have noted will 

 serve to illustrate principles to be stated hereafter. I wish 

 your imaginations to be impressed by the wonderful groups 

 of geysers and hot springs scattered through the Park. I wish 

 you to make the acquaintance of some facts from which we 

 may derive important inferences bearing on internal heat. Mr. 

 A. C. Peale, one of the United States geologists, has described 

 in the Park 2,195 warm springs, and expresses the belief that 

 three thousand exist. He has also named and described 

 seventy-one geysers. A geyser is a spring which periodically 

 throws up hot water to some distance above the level of the 

 ground. 



Let us take a particular geyser and note its situation and 

 the phenomena connected with its eruptions. "Old Faithful" 

 geyser is one of a group in the upper part of the valley of 

 Firehole river. The external formation is a mound or table 

 of geyserite or silicious sinter a whitish mineral composed 

 chiefly of silica and water, and deposited from the waters of 

 the geysers. The mound is one hundred and forty-five feet 

 by two hundred and fifteen at base, and twenty by fifty-four 

 feet at top. It rises about twelve feet above the surrounding 

 level, and is composed of layers of deposit arranged in a suc- 

 cession of steps that are made up of small basins. Near the 

 top these basins are beautiful, broad, shallow pools, with pink, 

 cream, white, brown and gray bottoms, in which the deep 

 azure-tinted water stands after the eruptions. The "chimney" 

 or " crater" is the top of a " basin" five feet deep, at the bot- 



