International Excursion in America. 
85 
solution. The soils of the Tooele valley are all more or less saline, 
with the exception of that of the sage-brush (uppermost) association, 
and that of the sand hills mixed association (which was not visited 
by the party). 
The following associations were distinguished by the Department 
of Agriculture workers and demonstrated to the international party. 
(1) . Sage-brush association dominated by Artemisia tridentata. 
This occupies the highest alluvial fans and benches nearest the 
mountains and has the most sandy soil (with the exception of the 
sand hills—not considered here), the lowest moisture equivalent 
and the lowest salt-content (’03 to ’07%) of any of the associations. 
At the time of this visit the association was very poor floristically, 
the dominant sage-brush being practically pure, with societies of 
Gutierrezia and some Agropyron spicatum. There is, however, a 
distinct vernal flora coinciding with the rains of May (the wettest 
month, averaging 2’4 inches), and containing Phlox, Castilleia, 
Delphinium, etc. During the summer the surface foot of soil is 
dry, the water-content sinking below the wilting point, and the next 
few feet of soil are similarly dry in late summer. Juniperus 
Utahensis occurs in this association near the mountains. 
(2) . Kochia vestita association. This occupies the next zone 
and is again nearly a pure association of the dominant. The soil 
is more clayey, the surface foot to which the roots of Kochia are 
confined being leached of salt (surface foot '12%, fourth foot Ml%). 
The moisture equivalent is a good deal higher than in the sage-brush 
association, the summer water-content being still below the wilting 
point. 
(3) . Shadscale association, dominated by A triplex confertifolia 
occupying the next lower zone does not differ markedly in physical 
factors from the previous association. 
(4) . Greasewood-shadscale association dominated by a mixture 
of Atriplex confertifolia and Sarcohatus vermiculatus. The moisture 
equivalent of this association does not differ much from those of 
the two last, but the average summer water-content is much higher, 
and except in the surface foot available water is present during the 
summer. The salt-content is decidedly higher at all depths, though 
the leaching effect is still observable in the surface foot. This is 
apparently the factor which brings in the greasewood, a pronounced 
halophyte. It is said that the availability of the water-content is 
1 The quantity of water, expressed as a percentage of the dry weight of 
the soil, retained by the soil against a centrifugal force 1,000 times the force 
of gravity. 
