PEALE.J 



UPPER GEYSER BASIN — GRAND GROUP. 



213 



tions was 26 hours. The third eruption began with 73 pulsations to the 

 minute, which gTadually died down to 71, and finally ceased entirely. In 

 the third period the main eruption lasted only about 3 minutes, the other 

 7 being occupied by preliminary spurts, the maximum height being at- 

 tained just 1 minute before the end. Just before it began the steam vent 

 near by ceased acting. In the second period there were two quiet iuter- 

 vals, lasting a minute and a minute and a half. The maximum was at- 

 tained on the first spurt, and the duration of each of the three spoutings 

 was 30 seconds. 



The maximum in the first period was reached in 30 seconds. 



Preceding the eruption the water in the basin was lifted in a dome- 

 shaped mass, and then the steam shot through it, carrying up the 

 water in a mass that was somewhat x>yramidal in shape. The highest 

 jets were projected through this. The column was not much obscured 

 by steam. After the action ceased, water ran into the basin from sev- 

 eral channels, and in 3 minutes had sunk out of sight. Twenty-two 

 minutes after the end, steam was still escaping from the orifice. About 

 half an hcmr later the basin was filling, two large streams from the over- 

 flow of the Turban pouring in. In the Grand it was pulsating, falling 

 from 1 foot to 6 or 8 feet, and rising again with occasional squirts. 

 During this time the Turban was spurting, ami the adjoining steam 

 vent was in irregular action. I am of the opinion that the Grand, Tur- 

 ban, and steam vent are independent of each other. Professor Comstock, 

 however, thinks there is sympathy to a certain extent. 1 shall refer to 

 this again when speaking of the Turban Geyser. 



1873. — Professor Comstock witnessed one eruption of the Grand in 

 1873, which he describes as follows : 



Passing down the river a few rods, upon the right bank we saw a heavy mass of 

 ■water rising in a square pool at the foot of a cliff some ten rods back from tho stream. 

 With a rush of wonderful power the column of dark bhie liquid ascended nearly 

 200 feet, mingled with a cloud of dense white vapor, which rose to a much greater 

 height. This tremendous fountain was keptsusi^ended during five minutes, from 4.01 

 p, m., to 4.06 p. m. by aseriesof successive fierce impulses, which caused the surround- 

 ing platform of geyserite to tremble with the shock. The water then receded in the 

 bowl, passing entirely out of sight, and remaining quiet during one-half minute ; then 

 playing vigorously for one minute in the same manner as at first ; it again receded 

 and remained quiet for one minute, afterward playing once more, even more fiercely 

 than before, for two minutes, remaining quiet from 4.11 to 4.12, and then continuing 

 with more or less of vigor until 4** 12'" 5^ p. m. At 4'' 17™ 5^ p.m. vapor issued from the 

 mouth of the bowl, and water was ejected at 4'' 20™ 5=, continuing until 4.24, when the 

 action ceased, the water, as in every case, receding to a great depth. Spurting took 

 place at 4"^ 28'" 5^, gradually increasing in intensity, with occasional jets, until 4.31, 

 when it again spouted 200 feet till 4^ :^2'n 5^ p. m. Remaining quiet until 4'' 48™ 5^ it 

 aga,in spurted several times, less rapidly than before, but very gradually increasing in 

 power and frequency, till 5.47 p. m., when the action wholly ceased.* 



In this eruption there would appear to be four periods instead of 

 three, as in the eruptions noted in previous years. Tabulating them, 

 we have the following : 



No. of period. 



Spouting 

 begins. 



Duration. 



Intervals of 

 quiet. 



Maximum 

 height. 



First 



h. m. 8. 

 4 01 p. TO. 

 4 20 5 p. m. 

 4 28 5 p. m. 

 4 48 5 p. in. 



m. 8. 



U 15 

 ,•! 55 

 4 00 



58 55* 



m. 8. 



Feet. 



Second 



Third 



7 50 

 4 5 

 10 





200 



Fourth 





*T think the time of ending, 5.47, should bo 4.57, which which would give a duration of 8" 55", instead 

 of 58"> 55V 



"Report of Reconnaissance of N. W. Wyoming in 1873, p. 252. 



