VOL. 5] Contributions to Western Botany, No. IX. 51 
Creek mountains, till it passes beyond the northern end of the 
Granite range, after that it occupies the center of the flat area 
south of Pilot Peak and east of Dutch Mountain (which is the 
northern extension of the Deep Creek mountains) there is prob- 
ably no part of it that is over 40 miles wide. This barren area 
has no pebbles, gravel, or sand, it is wholly a compact yellow 
clay, like putty, carrying a small percentage of soluble salts, 
probably not exceeding 10 per cent. in any case. These salts 
are mixed in about the following proportions: chloride of sodium, 
8 per cent.; chloride of magnesium, 1 per cent.; sulphate of 
sodium, .7 per cent.; sulphate of potassium, .3 per cent.; sulphate 
of calcium, .og per cent. In addition to the above there is a 
variable amount of carbonate of sodium which will raise the 
total percentage of soluble salts somewhat, but this latter is never 
great in the barren area, it seems to be confined mostly to the 
surface, though there are places outside uf this part of the desert 
where the carbonate of sodium is in excess of the chloride of 
sodium and is evidently caused by the decomposition of the 
Palzeozoic limestones and adjacent rocks. There are places in 
this desert where, by a process of natural (in distinction from 
articificial) precipitation, the more soluble salts have been de- 
posited separately from the chloride of sodium, and in separate 
places. In such cases, when the soil contains only common salt 
(chloride of sodium) on drying it becomes perfectly solid, 
smooth and without a crust, but dries very slowly, and is un- 
affected by the agencies mentioned below, but when the soluble 
elements are complex, as is the case in the barren area, then, on 
drying, there is a white crust formed of concentrated salts which 
is raised % to an inch above the moist soil below and is mixed 
with more or less yellow clay which it has taken up on parting 
from the soil below. Sometimes this crust is mostly salts, and 
generally it is at least % soil, and light and fluffy but glistening 
with salts. This crust the high winds, which prevail over the 
desert, take up and carry far away in clouds. If a rain should 
follow one of these storms of wind, then the soil and salts are 
washed out of the air and we have, what seems to be peculiar to 
Salt Lake City, salt showers. These are rare in the city, but 
