22 BULLETIN UNITED STATES aEOLOGICAL SUEVEY. [Tol.Yl. 



in the terms employed by Mr. Watson in King's Exploration (Rep. xxiv, 

 XXV), which, is here accordingly cited : 



" No portion of this whole district, however desert in repute and in 

 fact, is destitute of some amount of vegetation even in the driest seasons, 

 excepting only the alkali flats, which are usually of quite limited extent. 

 Even these have frequently a scattered growth of Sarcohatus or Halos- 

 taehys, surmounting . isolated hillocks of drifted sand, compacted by 

 their roots and buried branches. 



" This vegetation, covering alike the valley plains, the graded incline 

 of the mesas, the rounded foot-hills, and the mountain slopes, possesses 

 a monotonous sameness of aspect, and is characterized mainly by the 

 absence of trees, by the want of a grassy-green sward, the wide distribu- 

 tion of a few low shrubs or half-shrubby plants, to the apparent exclu- 

 sion of nearly all other growth, and by the universally prevalent gray 

 or dull olive color of the herbage. * * * The turfing ' Buffalo ' or 

 ' Grama ' Grasses, which make the plains east of the Rocky Mountains a 

 vast pasture for the bison, deer, and antelope, are here unknown. There 

 are, indeed, various other species more or less abundant in localities, 

 but always growing in sparsely scattered tufts and dying away with the 

 early summer heats, or to be then found only in favored spots in the 

 mountain caiions. Two or three species that may be said to mat into a 

 sward are confined to alkaline meadows, and are nearly worthless for 

 pasturage. 



" Of the more predominant species which form the mass of the shrubby 

 and perennial vegetation of the entire region, some are confined almost 

 wholly to the more saline localities. Of these the Halostachys occiden- 

 talis is an exclusively alkaline shrub, growing where almost no other 

 plant will. Much more widely distributed and abundant is the Sarcoha- 

 tus vermiculatus, found nearly everywhere in the lower valleys where 

 there is a decided amount of alkali, but rarely extending much beyond 

 such limits. The more frequent plants accompanying these are Salicor- 

 nia herbacea and several species of Suceda, and other mostly Chenopodia- 

 ceous plants, and, if there are grasses at all, Brisopyrum spicatum and 

 Spartina gracilis. 



" On the somewhat less alkaline and drier portion of the valleys are 

 found in frequent abundance Atriplex confertifolia and canescens, or the 

 nearly as common Grayia polygaloides, and rather less abundantly 

 Artemisia sjnnescens, Eurotia lanata, and Kocliia prostrata. Sometimes 

 mingled with them, but. wholly free from alkaline preferences, and 

 beyond their range usurping entire predominance, is the ' Everlasting 

 Sage Brush,' the Artemisia tridentata. This is by far the most prevalent 

 of all species, covering valleys and foot-hills in broad stretches further 

 than the eye can reach, the growth never so dense as to seriously obstruct 

 the way, but very uniform over large surfaces, very rarely reaching the 

 saddle-height of a mule, and ordinarily but half that altitude. 



"The 'Broom Sage' Bigelovia graveolens occurs in considerable abun- 



