138 GEOLOGICAL SURVEY OF THE TEERITORIES. 



Having completed observatious on these springs, I devoted the re- 

 mainder of my time to those near camp, which presented a great deal of 

 interest. I was enabled to make more accurate observations than were 

 made last year, and was greatly assisted by Mr. A. E. Brown, who de- 

 termined the heights of the mud- geyser for me. The mud-geyser is the 

 principal sirring in the group at Mud Yolcauoes, and was situated a few 

 yards above our camp. It has a basin of about 60 feet diameter, sur- 

 rounded by a rim that slopes inward, at an angle of 3-0°, to a funnel- 

 shaped orifice in the center. This basin, which is the basin proper of 

 the geyser, is made up principally of clay and silica, and is situated in 

 another basin which measures 200 feet by 150 feet. The wall of this 

 latter basin rises about 8 feet, on an average, above the level of the 

 other basin, and between the two rims there is a deposit of clay which 

 has been left by the water and has become hard, resembling a very 

 fine clay slate. On one side of the outer basin there is a small ravine- 

 like opening cut into the bank, through which water evidently flows 

 sometimes, probably during the spring when there is more water in the 

 basin. In several places on the banks I noticed small holes lined with 

 sulphur from which the steam escapes. Besides the geyser there are 

 two small springs at one end of the large basin. These springs are en- 

 tirely independent of the geyser, and are constantly in action, bub- 

 bling quietly. They do not seem to be affected in the least by the 

 eruptions of the geyser. The following is the description of an eruption : 

 The water gradually rises until the inner basin is filled, wiien there 

 is noticed a bubbling in the center. Suddenly, without any fur- 

 ther warning, it becomes violently agitated and an immense mass of 

 muddy water, mingled with clouds of steam, is thrown into the air. 

 This action lasts a few minutes and is followed by a lull, the action not 

 ceasing entirely. Then it recommences with renewed violence, and the 

 water tills the entire outer basin, the water striking the banks in a succes- 

 sion of waves. The water is thrown up in a succession of impulses that 

 follow each other rapidly, and sometimes the water is thrown obliquely 

 and seems as though it would overwhelm one standing on the bank. 

 The mass of water and mud is immense. After the maximum height 

 is obtained the jets become smaller and smaller, and the eruption ends 

 as suddenly as it began. It is a very impressive sight, and the stop- 

 ping is like a calm after a storm. The water of the geyser is very muddy, 

 and bluish in color, having an acid reaction, due to the presence of sul- 

 phuric acid.^ 



I will transcribe ray field-notes below and then give the result in tabu- 

 lar form, so that the whole may be placed before the eye at once. 



August 11. 



4.02 p. m. — The temperature of water in the basin is 140° F. and the 

 air 50° F. 



4.37 p. m. — The water is rising rapidly and there is considerable bub- 

 bling in the center of the basin, the temperature remaining the same. 



4.42 p. m. to 4.52 p. m. — The water is still rising and flows in currents, 

 giving it a variable temperature of 140° F. to 180° F. 



5.02 p. m. — The temperature is still 180° F. at the edge, although in 

 the center it must be considerably higher. It is still in ebullition. 



5.04 p. m. — The eruption commences. 



5.10 p. m. — There is a lull in the action. 



5.14 p. m. — The maximum (40 feet) is attained. 



5.17 p. m. — The eruption ends and the water at the edge of the basin 

 has a temperature of 172° F. 



