15 



A sample from Bitter Creek flats (second bottom land, on which salt- 

 sages flourish) shows tlie following composition : 



Alkali (water-soluble salts), 0.<% per cent of soil. 



Composition of alkali : 



Per <-.ent. 



Sodinni chloride 74. 1 



Sodium sulphate 25. 9 



100.0 

 On tlie first bottom or low banks of Bitter Creek, on which Atriplex 

 pabularis, Agropyron tenerwn, Chrysoiliamnus lini/olius, and one or two 

 species of Jnncus and Scirpus flourish, we find a much greater salt 

 content, as the following analysis shows: 



Alkali (water-soluble salts), 8.67 per cent of soil. 



Composition of alkali: 



Per cent. 



Sodium chloride 6. 44 



Sodium sulphate 83. 12 



Calcium sulphate 5. 39 



Magnesium sulphate 3. 35 



Iron and aluiuinum 1 . 70 



100. 00 

 As indicating the presence and amount of sodium carbonate, the fol- 

 lowing analysis of a sjimple from Orendo Butte will be of interest. The 

 ground from which this was taken undoubtedly has its counterpart in 

 many other localities in the desert: 



Alkali (water-soluble salts), 7.20 per cent of soil. 



Composition of alkali : 



Per <'ci)t. 



Sodium chloride 4. 08 



Sodium sulphate 50. 41 



Sodium carbonate 45. 51 



100. 00 

 Without giving any more of the analyses in detail, it may be stated 

 that the foregoing do not represent the soils in which the largest 

 amounts of alkali are present and vegetation still existing. In the 

 bed of a dry pond a species of H^cirpus was growing where the surface 

 soil contained more than GO per cent of soluble salts. 



CLIMATE. 



No reliable data are at hand from any locality within the desert 

 either as to temperature or precipitation. On this account only general 

 statements can be made, based upon limited personal observation and 

 such information as could be gathered from the residents of the region. 



TEMPERATURE. 



The temperature is certainly very variable, rising during the long, 

 clear days of summer to almost tropical heat and falling at night nearly 

 or quite.to the freezing point. The dry, rarefied air of these high alti- 

 tudes permits the free passage of the sun's rays, so that during still days 



