GEOLOGICAL SUEVEY OF THE TEEEITOEIES. 245 



arebigh, smooth, and rounded foot-liills, behind which arise loftier mount- 

 ains, from which the snow bad not disappeared at the time of our visit. 



From here we moved northeast some fifteen or sixteen miles to Fort 

 Hall, not the old Fort Hall of the maps, situated on the west bank of 

 Snake Eiver, but the new fort built east of the river, about thirty miles 

 from the old locality. Traveling up the little stream for five or six 

 miles we found it somewhat closely hemmed in by the hills, yet here 

 and there affording small areas of level bottom-land covered with a lux- 

 uriant growth of grass. The rest of the distance, some eight or ten 

 miles, was taken up in ascending and descending the lofty foot-hill we 

 had to cross to reach the fort. Here we had one of the finest exhibi- 

 tions I had seen of those smooth, peculiar hills which look so much 

 like the folds in a lady's dress. This comiDarison may appear somewhat 

 ludicrous ; but while gazing from the summit of this ridge on the end- 

 less succession of the smooth, grassy ridges and hills piled and rolled 

 together to form the large ridge, distance giving the grassy covering 

 the appearance of velvet or silk, the colors of the folds varying as if by 

 the difference in reflection of the light, the resemblance to the folds of 

 rich cloth was more than simply fancy. Over an area of perhaps one 

 hundred square miles I saw but three or four trees, standing as lonely 

 remnants of the forests which once doubtless covered this entire area. 

 It is evident that these hills and ridges were once rugged, and that by 

 the action of water, snow, ice, &c., the rocks have gradually been worn 

 down until the surface has been covered with the triturated debris, thus 

 giving it the present smooth appearance. That these rugged spots 

 which remain are covered with forests is evident to all who have trav- 

 eled over the Eocky Mountain region ; and I think we have sufficient 

 evidence to show that these now smooth ridges, before their former 

 ruggedness was worn down, were also covered with forests of pine and 

 fir. Here I also observed that there was presented in a marked degree 

 that peculiar arrangement of colors belonging to elevated regions; one 

 side and the top of each of the descending ridges being pale-green or 

 gray, while the other side or part of it was of a deep grassy-green. 

 These variations tell us very plainly the direction of the prevailing 

 winter winds -, for the greener spots mark the place where the snow 

 lay the longest, showing thereby that they are on the side opposite that 

 from which the wind came. 



Fort Hall is situated among the mountain foot-hills on a little stream 

 that makes its way northwest to Snake Eiver. A small area of ground 

 may be irrigated around it, probably not more than five or six hundred 

 acres. Th6 ofl&cers in charge of the post are making some experiments 

 in horticulture and agriculture, and though laboring under many dis- 

 advantages, the vegetables and cereals I saw growing there at the time 

 of our visit indicate that wheat, oats, potatoes, cabbages, turnips, and 

 pease can be produced without any serious difficulty on account of the 

 sev^erity of the climate. 



The dryness of the air was found to be very great here, the difference 

 between the wet and dry bulb reaching, in some cases, 34°, and stand- 

 ing generally each day during our stay at from 25° to 28°. During the 

 middle portion of the day we found the rays of the sun hot and oppress- 

 ive when there was no breeze blowing. 



As a general thing timber is scarce throughout this entire region, 

 that of value for lumber being found only on those mountains whose 

 summits are covered with snow all or a great part of the summer. 

 And here, as elsewhere in the whole Eocky Mountain belt, when the 

 forest is once destroyed it is never restored. Most of the best lumber 



