PEALE.] GIBBON GEYSER BASIN. 127 



No. 16 is a bulger, sending water to the height of a foot or two from 

 the center of a basin which measures 8 feet diameter. The water is 

 turbid and has a temperature of 182° F. 



Ko. 17 is a white boiling spring 8 feet in diameter. 



^o. 18 is a semi-turbid spring, about 10 feet in diameter, and bulges. 



No. 19 is a milky-tinted pool, 15 feet long by 6 or 8 feet wide. 



No. 20 is a bulging pool 15 feet in diameter. 



No. 21 is a circular basin, 3 feet in diameter, with a bright red bor- 

 dered hole in the center, from which water and steam are alternately 

 spurted. Around No. 21 are a number of vents, sulphur holes, and turbid 

 springs. The surface is too treacherous to allow of temperatures being 

 taken. 



No. 22. Grindstone Springs. This is a collection of circular mud mounds 

 with small circular orifices, about a foot each in diameter. The mounds 

 are several feet in diameter, and resemble a lot of grindstones as much 

 as anything. No. 22 and 22a are the most perfect. Between these 

 springs and the road are a number semi-turbid springs. 



No. 23 is on the right of the road, and is a greenish sulphur pool. 

 Near it is a lake-like pond. 



No. 24. Opal Spring is on the mound forming the Eastern boundary 

 of the depressed basin. It has bluish-white water, which flows from 

 the spring over ocher-yellow terraces. Between the spring and the 

 depressed basin there is a slope covered with minute terraces, over 

 which the water flows from a small fissure. The tint of the water 

 in the spring is probably due some substance held in suspension, the 

 temperature being only 90° F. On the mound above the spring there 

 are fissures and holes, from which both steam and water escape. One 

 has a peculiar, trough-like, small basin, from one end of which the water 

 spurts. There are also old crater-like holes, with small mounds about 

 6 inches in height. 



No. 25 is a long bluish-white pool on the summit of the mound. There 

 is a small spurting geyser at one end. The pool is constantly agitated, 

 and there is a large escape of steam. 



No. 26 is a bulging and spouting milky-hued spring, with three cen- 

 ters of ebullition on the slope of the hill. It is 8 by 15 feet, and the hill 

 back of it is coated with sulphur and alum. A great quantity of steam 

 escapes. 



No. 27 is a fissure back of No. 26. There are several lioles from which 

 steam escapes in large volume. One of the holes is yellowish-white, 

 another white, and all boil vigorously. 



No. 28 is a spouter on the line of tlie fissure of No. 27. The water is 

 clear, in a basin of hard geyserite measuring 4 by 8 feet. 



No. 29. Mound Geyser. — This is a flat-topped mound or platform meas- 

 uring about 12 by 15 feet, and rising 6 inches to a foot above the general 

 level. The orifice in the center of the platform measures 3 inches by 1 

 foot, and sends out with great force alternately a spurt of water and 

 steam. In this it resembles No. 21. 



No. 30 is a dark-gray sulphur pool about 20 feet in length. The edge 

 is sulphur-lined, and at one end the water bulges and boils violently. 

 Between Nos. 29 and 30 there are sulphur-lined vents. 



No. 31 is a semi-turbid sulphur pool which bubbles slightly. 



No. 32 is a creamy-white thin-mud pool, in which the mud or muddy 

 water is in constant agitation. 



In the valley below these springs there are large ponds, or lakes, of 

 greenish-yellow tint. The largest receives water from the siuings in- 

 cluded under Nos. 29 to 32. There appears to be no outlet, although the 



