GEOLOGICAL SUEVEY OF THE TERRITORIES. 



73 



on Gardiner's Eiver. Upon the summit of the Tertiary and Cretaceous 

 strata, at the right, is a bed of basalt. While passing by, under the 

 river and beneath the 

 calcareous deposit of the 

 springs, are the Carbon- 

 iferous limestones; be- 

 neath all, we suppose, 

 there is a great thickness 

 of trachyte. We may 

 also suppose that the 

 meteoric waters pass 

 up to the surface 

 through the limestone, 

 as shown in the section, 

 cleaving the lime that is 

 deposited on the way. 

 This subject will be dis- 

 cussed more fully in a 

 future report. 



We have already spo- 

 ken of the wedge-like 

 ridge between the Yel- 

 lowstone and Gardiner's 

 Elvers, and the wall of 

 Cretaceous Tertiary, and 

 basaltic strata facing the 

 hot-spring district. 

 These consist of alternate 

 beds of dark-brown clays 

 and somber-gray sand- 



stone, some portions 

 thinly laminated or com- | ^^^p 

 l)act like quartzite ; in- 

 clination, east 10<^. 

 These beds extend up in 

 their fall force about 

 three miles above the 

 springs on the east side 

 of the East Fork, where 

 they become obscured by 

 basaltic rocks and detri- 

 tus. Masses of basalt 

 have fallen down from 

 the summit of the ridge 

 into the valley below, in 

 many instances obstruct- 

 ing the current and ren- 

 dering traveling difficult. 

 About a mile above the 

 springs, Gardiner's Eiver 

 separates into three 

 branches, which we may 

 call East, Middle, and 

 West Forks. Tlicy take 

 their rise high up in the 

 divide that separates the 

 lake basin from the valley below. I have estimated the length of these 



