214 GEOLOGICAL SURVEY OF THE TERRITORIES. 



As we approach camp on Conant Creek, there is a marked change in 

 the flora, from that of the dr^ j)lains, which are mostly bare through 

 the Aviuter, to that of the wetter hills, on which the snow then lies in 

 drifts. Aspens begin to a])pear in considerable numbers, and antelopes 

 are becoming rather abundant. 



Julii 21. — The country is becoming much more rollinp;, with a slight 

 general slope of the surface toward Pierre's River, lieachiug the lowest 

 tributary of that stream, we found it tiowiug between nearly vertical 

 banks, from 250 to 300 feet high, the lower parts of which are composed 

 of light and dark pink compact porphyries, mostly ringing under the 

 hammer, while the upper beds consist of gray basalt, somewhat porous 

 and partly coarsely vesicular. On the hills between the streams, porous 

 porphyritic trachytes reach the highest crests. Crossing the caiion, we 

 camped on a small run which falls over the bluff just below. The caiion 

 has here a very tortuous course. Mr. Bechler descended to its junction 

 with that of the main stream of Pierre's River, and found it everywhere 

 bounded by nearly vertical walls, here from GOO to 700 feet in height. 

 The last rattlesnake seen on the trip, so far as rei)orted, was killed near 

 this point. These reptiles are said to be always rare in the higher parts 

 of the mountains. Strawberries were abundant at this camp. 



The peak of the Grand Teton had been gradually rising as we had 

 approached, until now it was so near that strong glasses could give us 

 pretty good ideas of its structure. It was now plainly evident that this 

 was not a volcanic peak, as had been reported, but that it consisted of 

 either quartzites or granites. The gravel which filled the bottom of the 

 caiion consisted largely of granites, gneisses, serpentines, &c., which 

 gave sure indications of the existence of these metamorphic rocks about 

 the sources of these streams ; so that the probabilities were strong that 

 the central peaks would prove to be granitic. A few limestone-peb- 

 bles were also seen, but these were mostly iiretty well ground up. 



From near this camp there is a general depression of the surface, 

 stretching across to the nearest point of Pierre's Hole, (or Teton Basin, 

 as it is sometimes called,) and suggesting the possibility that it may 

 have been a broad stream -valley, after the outflow of the basalt and 

 before the erosion of the caiions. If this were ever the case, the weath- 

 ering of the slopes has destroyed any distinct channel, and so has ren- 

 dered a decision of the case very difficult. By very moderate slopes we 

 descended into Pierre's Hole. This has a nearly plain surface for a 

 length of about twenty miles and a breadth varying from about five to 

 twelve or fifteen miles, beyond which limit gentle slopes stretch up far 

 among the foot-hills. The general slope of the plain, as a whole, is so 

 extremely gradual that the flow of the streams which pass through is 

 very niuch checked, so as to cause broad stretches of swampy ground 

 along their banks, which are nor at all bettered by being occupied by 

 numerous beavers. Many of the small streams, as they emerge from 

 the mountains, are divided into severa.1 channels, which take very dif- 

 ferent courses to the river. Most of the plain is thickly covered with a 

 luxuriant growth of grasses and other good forage-plants, though some 

 small areas are sandy and comparatively barren. Abundant supplies 

 of water for irrigation, if this should ever become necessary, can be 

 had at the mouth of every little caiion. The seasons are probably too 

 short for corn, but wheat should succeed well here. Considering the 

 richness of the soil and the abundance ©f water, this is one of the most 

 inviting valleys of the region, and would doubtless soon be settled if 

 railroads should come within convenient distances. This was formerly 

 one of the favorite summer-rendezvous of the old fur-traders, and was 



