PEALE.] MAMMOTH HOT SPRINGS OF GAEDINER'S EIVER. 79 



is irregular in sliape, and tlie water comes out from a fissure and has a 

 temperature of 144° F. In 1871 it was 150° F., which appears to indicate 

 a diminution in its activity. The ridge back of the ninth terrace (Plate 

 Yd) is the tenth terrace of the table in the report for 1872. It has been 

 described, and I pass on to the next terrace level. 



JEIeventh terrace of 1872. — This terrace is 40 feet above the ninth terrace, 

 and has an area of over 13 acres, over which grass grows to a great extent. 

 The principal spring (24) is near the edge of the terrace that overlooks 

 the gullj between the terrace, and the ridge just back of the ninth 

 terrace. 



'^o, 24. — This spring is a couple of inches in diameter, and the water 

 as it comes from the deposit spreads out to the right and left over a 

 white surface coated with yellow sulphury filaments that appear soft 

 and silky. The water that goes to the right disappears in a sink-hole 

 about 150 feet distant. The temperature is 162° F., which is higher 

 than that observed in 1871 (156|o). The terrace level extends south- 

 ward to the high blutf of the thirteenth terrace. On the west is an- 

 other ridge, on the summit of which is a fissure and a cone which once 

 were active springs. The water still bubbles slightly in them, but they 

 do not deserve the name of springs. Where the road crosses the end 

 of this ridge next to the hill the water oozes from the deposit. Extinct 

 basins are found on the sides of the ridge. Between this ridge and the 

 bluff of the thirteenth terrace is a mound with dry basins on its sides. 

 Toward the ridge just described a spur of old deposit extends from the 

 thirteenth terrace, in which the laminated overlapping structure of the 

 mounds is well shown in the places where it has weabhered and has 

 been broken down. Some of the mounds are overgrown with pine trees 

 which give evidence of the age of these deposits. This, however, is 

 more particularly noticed on the thirteenth and fourteenth terraces, and 

 will be referred to again. The best view of the springs of the ninth 

 terrace is to be had from the edge of the eleventh terrace, which directly 

 overlooks them. Dr. Hayden, in the report for 1871, describes it as fol- 

 lows : 



The wonderful transparency of the water surpasses anything of the kind I have 

 ever seen in any other portion of the world. The sky, with, the smallest cloud that 

 flits across it, is reflected in its clear depths, and the ultramarine colors, more vivid 

 than the sea, are greatly heightened by the constant, gentle vibrations. One can look 

 down into the clear depths and see with perfect distinctness the minutest ornament 

 on the inner sides of the basins ; and the exquisite beauty of the coloring and the 

 variety of forms baffle any attempt to portray them, either with pen or pencil. And 

 then, too, around the borders of these springs, especially those of rather low temper- 

 ature, and on the sides and bottoms of the numerous little channels of the streams 

 that flow from these springs, there is a striking variety of the most vivid colors. I 

 can only compare them to our most brilliant aniline dyes — various shades of red, from 

 the brightest scarlet to a bright rose tint; also yellow, from deep-bright sulphur, 

 through all the shades, to light cream color. There are also various shades of green, 

 from the peculiar vegetation. These springs are also filled with minute vegetable 

 forms, which under fhe microscope prove to be diatoms, among which Dr. Billings 

 discovers Palmella and OscAllara. There are also in the little streams that flow from 

 the boiling 8i)rings great quantities of a fibrous silky substance, api^arently vegetable, 

 which vibrates at the slightest movement of the water, and has the appearance of the 

 finest quality of cashmere wool. When the waters are still these silken masses be- 

 come incrusted with lime, the delicate vegetable threads disappear, and a fibrous 

 gpougy muss remains, like delicate snow-white coral. 



At present the colors are white and red, with which the blue color of 

 the spring contrasts beautifully. At the south end of the eleventh ter- 

 race is a long, narrow, spur-like ridge from the thirteenth, covered with 

 a growth of pines. Crossing this we come to a somewhat inclosed area, 

 which is the twelfth terrace of 1872. 



