246 EEPOET UNITED STATES GEOLOGICAL SUKVEY. 



No. 3. Green Spring. — This spring', on the map of 1872 and in Plate 

 XXVII, is called Emerald Sprin,^, but the tint is bluer than an emerald 

 color, so I have called it simply Green Spring, especially as there is an 

 Emerald Spring on the opposite side of the creek. This basin is some- 

 what heart-shaped, and consists of a deep cavern-like pool and a smaller 

 shallow gray pool near the outlet. The temperature was 195° F. A 

 temperarure taken here in 1871 was only 170° F. 



IS'o. 4. — This is a very handsome oblong pool of greenish-tinted water, 

 with an overhanging white scalloped rim. There is a boiling center at 

 the back of the spring. This is the spring shown in Plate XXV. 



Xos. 5, 6, and 7 are unimportant springs, sufficiently described in the 

 table. 



Xo. 8. Great Hot Basin. — The water from this bulging basin flows 

 over brilliant red terraces. The basin is generally flat, except in the 

 center. The temperature (188° F.) was taken at the north edge. In 

 the background of Plate XXVII, near the trees at the right, the steam 

 from this spring is seen rising. 



Xo. 9. — In this spring there are two basins, only one of which con- 

 tained water when examined. At times, however, the water fills both, 

 making one spring. 



Xo. 11. Emerald Spring. — It is somewhat irregularly rectangular in 

 shape. In the center is a rhomboidal-shaped pit or bowl 35 feet in 

 depth, over which the water is of a deep emerald green color, becoming 

 yellowish green towards the edges. Outside of this central bowl is a 

 shallow basin reaching to the edge of the spring, which is bordered by 

 a red and brown line. This shallow portion is light yellow in color. 

 The tint over the central bowl is so deep that the bottom cannot be 

 seen. The water-ways which carry off the overflow are brilliantly red 

 on a brown and grayish white ground. The deposit covers a consider- 

 able area, and scattered over it are a number of dead standing trees. 



Xos. 12 and 13 are not indicated on the map. They are on the creek 

 bank. 



Xo. 14 (Plate XXVI) is on the bank of the creek at a bend, and its 

 basin rises from the water's edge. The water has an inky tinge over 

 one orifice, and at the other the basin is grayish white. The border is 

 corrugated, with a gray edge and yellow beaded silica on it. The main 

 orifice bulges at short intervals. 



Xo. 15. Blacli Sand Geyser (Plate XXVIII). — This is one of the most 

 beautiful springs in the Upper Basin. It has a delicate rim, with toad- 

 stool-like masses around it. The basin slopes rather gently towards 

 a central aperture that to the eye appears to have no bottom. The 

 water in the spring has a delicate turquoise tint, and as the breeze 

 sweeps across the surface, removing the steam, the effect of the rippling 

 of the water is very beautiful. The sloping sides are covered with a 

 light brown crust ; sometimes it is a rather dark cream color. The fun- 

 nel is about 40 feet in diameter. The entire space covered by the water 

 is about 55 feet by 60 feet. Outside the rim of the spring is a border 

 of i^itchstone (obsidian) sand or gravel sloping 25 feet. 



From the west side flows a considerable stream, which forms a most 

 beautiful channel, in which the colors show a remarkable variety of 

 shades. The extremely delicate jjinks are mingled with the equally deli- 

 cate saffron yellows, with here and there shades of green. These colors 

 are from deep yellow to pale creamy salmon. The stream or outlet runs 

 down nearly to the base of the trachj'te wall on the west side of the 

 basin, spreading out over a large area, which is covered with its depos- 

 its. (See Plate XXIX.) The main channel, which carries off the largest 



