24G GEOLOGICAL SURVFA' OF THE TERRITORIES. 



tlie mound, covering? an area at least 40 feet across. Just behind the 

 monnd, and at its immediate base, there is a hirge ornamented open.iiig, 

 which partly tills before eruptions, but is emptied by them. Much of 

 the ejected water falls in such a way as to How back to this reservoir, 

 so as to keep up the sui)ply necessary to the eruptions. These occur 

 pretty regularly for some hours, at intervals of from 2 to 3 minutes, but 

 gradually decline in force, until the supply of water becomes exhausted. 

 Then the geyser is silent for several hours, until all the crevices, as well 

 as the surlace-i)ools, are again tilled with water, when its eruptions 

 recommence with niuch violence, the jets then reaching altitudes of 

 from oO to -40 feet. These again decline, and the series of phenomena 

 is repeated. As water gets low, the back pool sometimes receives some 

 of the steam-pressure and spouts from 5 to 8 feet. At one jjoint 

 OH the top of the mound, there are some small sul]>hur- vents, which 

 seem to be entirely disconnected with the water-pipes, but maintain 

 communi(;ations of their own with the volcanic; laboratory beneath. 



About no feet farther on, Shield Geyser has an ornamented mound 

 about 15 inches high, which incloses a shield-shaped opening, measur- 

 ing about 8 feet on ea(;h of two sides and 7 feet on the third, at the top, 

 but narrowing to 4 feet on- each of the two sides and 3 feet on the third, 

 a little lower, at what was water-level when I measured it. This s])outs 

 moderately at intervals yf a lew hours, but no special notes of its erup- 

 tions were taken. By its side its partner has an Irregular opening 

 about 8 feet long and varying from 10 inches to 3 feet in width. These 

 vents exhibited no svnjpathy with Minute Man. Their temperature is 

 11)00. 



Between Shield Geyser and the foot of the hill, Bosette Spring has a 

 tiiangular basin with sides of about 15, 20, and 25 feet, in whose shal- 

 low waters form many most perfect specimens of the beautiful thiu- 

 Jeaved rosettes already described as occurring in the Fire-Hole Basin. 

 The muddy bottom of this spring contains much sulphur. 



A little rocky knoll intervenes between this and the Bulging Spring, 

 which every few moments gives vent to large bubbles of steam, which 

 raise a considerable part of its surface from 1 foot to 3 feet, with a 

 bulging sound like that of liquid escaping from the bung of an over- 

 turned barrel. 



Forty feet beyond, the Soap-Kettle keeps up a furious boiling of col- 

 ored water, more or less covered with foam, looking like dirty soap-suds. 

 Its basin is lined with a yellowish-brown deposit. This has probably 

 been a strong spouter, but now' erupts only at long intervals, if at all. 

 Its mound is about 8 feet across, and is still 1 foot high, though disin- 

 tegrating. 



Forty yards farther, the Black Sulphur Geyser has three vents, in 

 small dark-colored mounds, which almost constantly si)it, but do not 

 spout much. An abundant black sulphurous deposit is formed along 

 the run from these vents. 



The Twins are two small symmetrical vents, from 4 to G inches across, 

 in a small mound which stands back against the foot of the hill. They 

 spout rarely and to but siiudl elevations. 



Several boiling springs occur at short intervals along the bottom. 

 About seventy yards tarther on, a Hat mound includes two large flat 

 openings whi<'h spout to the height of from 20 to 30 feet at short inter- 

 vals ; temperature, 102°. Above this jtoint, the sptings are of little 

 inrportance, though a few vents and old d(>posits occur at intervals for 

 a mile or two up the valley. One, near those last described, is a nar- 



