374 
Journal of Agricultural Research 
Vol. I, No. 5 
relatively insoluble calcium carbonate and neutral sodium sulphate. It 
is evident that a similar reaction would take place if magnesium sulphate 
were present, since magnesium also forms an insoluble carbonate. It 
consequently seemed desirable to examine the carbonate and sulphate 
measurements with a view to determining to what extent the absence of 
soluble carbonates was accompanied by the presence of sulphates. Of 
122 samples examined for carbonates and sulphates 13 contained neither 
carbonates nor sulphates, while 13 others contained carbonates but no 
sulphates, leaving 96 samples containing sulphates. Of these, 78 sam¬ 
ples were free from carbonates, 2 samples contained both carbonates and 
sulphates in measurable quantities, while in the remaining 16 samples 
traces only of both sulphates and carbonates were present. 
VEGETATION OF TOOELE VALLEY 
The plant covering of the area under consideration is typical of a large 
portion of the Great Basin, several of the most important types of vege¬ 
tation of that region being represented in Tooele Valley. Striking features 
of this vegetation are (1) the great extent of the areas occupied continuously 
by a single type of vegetation, (2) the sharpness of the boundaries between 
the areas occupied by each type, and (3) the great predominance of one or 
very few species in each type. 1 2 
CLASSIFICATION OF THE TYPES OF VEGETATION 3 
The principal types of vegetation of Tooele Valley, with the names of 
the species which are dominant in each, are listed in Table III. 
1 These are common characteristics of the vegetation of arid regions. Thus, Borszczow, as quoted by 
Ove Paulsen (Studies on the Vegetation of the Transcaspian Lowlands. Copenhagen, 1912,p. 22-23), states: 
"Here, as throughout the whole of Aralo-Caspia, it is a few specially characteristic forms which prevail; 
they repeat themselves continually so that the country has a very monotonous appearance. Other species 
are only subordinate to these. Where the character of the soil changes, these predominant species some¬ 
times change very quickly and give place to others, which in turn prevail until the soil changes again. 
This monotony and this repetition of certain species over vast areas is the third characteristic of the vegeta¬ 
tion of the Aralo-Caspian countries. It is no doubt a direct consequence of the uniformity of the climate, 
which again is mainly dependent on the slight vertical relief of the surface. * * * 
"In the Aralo-Caspian lands the soil in particular has such a great influence on the vegetation that a 
change of soil—other conditions remaining the same—often alters the physiognomy totally and almost 
abruptly without any gradual transitions. ” 
2 In view of the fact that the ecological plant geography of the Great Basin region is as yet but little under- 
stood, it seems inadvisable at this time to attempt to refer the plant associations of this valley to formations. 
The term "plant association, ” as used in this paper, signifies an assemblage of plants occupying a rela¬ 
tively uniform environment, having an easily recognizable appearance or "physiognomy " and characterized 
by the predominance of one or few species. 
