36 GEOLOGY OF SW. IDAHO AND SE. OREGON, [bull. 217. 
sample of one of these from near Dog Mountain, about 6 miles west 
of Narrows, gave the following result on chemical analysis : 
Analysis of efflorescence from near Narrows, Or eg. 
[Analyst, George Steiger.] 
Insoluble in hot water 1. 25 
Sodium oxide, Na 2 47. 49 
Water, H 2 (of crystallization) 10.08 
Sulphuric anhydride, SO s 11. 76 
Chlorine, CI 2.90 
Carbon dioxide, C0 2 (carbonic acid gas) 26. 33 
Boracic acid, B 2 3 . . .28 
Total 100.09 
PROXIMATE COMPOSITION. 
Insoliible in hot water . 1.25 
Sodium carbonate, Na 2 C0 3 55. 91 
Sodium bicarbonate, NaHC0 3 5. 98 
Sodium sulphate, Na 2 S0 4 20.88 
Sodium chloride, NaCl 6.17 
Sodium biborate, Na 2 B 4 7 (borax) .46 
Water, H 2 (of crystallization) 9. 44 
Total 100.09 
Judging from the above analysis, the efflorescence from which thei 
sample examined was obtained, if in sufficient quantity and commer- 
cially accessible, would be of value for the sodium carbonate and! 
sodium bicarbonate it contains, but not for its borax. 
Every surface incrustation of the nature described above, when of i 
sufficient quantity to be of commercial value in case it contains 
sodium bicarbonate, borax, etc., should be carefully sampled and a 
representative portion analyzed. In every playa also auger holes 
should be bored for the purpose of discovering if deposits of valuable 
salts exist below the surface. The clays and silts in a playa should;; 
also be tested, as they may have absorbed sufficient borax or other: 
salts to make them of commercial value. 
GEOLOGY. 
RECENT VOLCANOES. 
Some account of the recent but now extinct volcanoes of southern 
Idaho was presented in my report on field work done in 1901, a and 
additional data in this connection were obtained during the recon- 
naissance which furnishes the basis of the present report. In 1902 
the Cinder Buttes, the most instructive group of recently extinct vol- 
canoes thus far discovered in Idaho, were revisited, and three separate 
centers of recent volcanic activity in southern Oregon, not previously 
a Bull. U. S. Geol. Survey No. 
