376 
Journal of Agricultural Research 
Vol. I, No. s 
The middle portion of the valley resembles the upper portion in the 
dryness of the soil and subsoil during the summer, but differs in the high 
salt content of the subsoil. This territory is divided between two types 
of vegetation, the Kochia (PI. XLVI) and the shadscale (PL XLVII, 
fig. i) associations. The former occupies a sharply defined interrupted 
belt extending well across the valley just south of the sagebrush 
area and also penetrates the latter in the form of tongues and islands, 
which occur here and there far toward the head of the valley. (PI. 
XLHI, fig. 2.) Lying just below the main Kochia belt an extensive tract 
is occupied by the shadscale association, which on the western side of 
the valley is prolonged in a gradually narrowing strip to the north end 
of the Stansbury Range. While the boundary between the sagebrush 
and Kochia associations is often very sharp (PL XLVI, fig. i), that 
between the Kochia and shadscale associations is much less distinct. 
It is probable that the water of Lake Bonneville had become strongly 
saline before the areas now occupied by the Kochia and shadscale asso¬ 
ciations were laid bare and that the subsequent precipitation has been 
too small to leach the salts then deposited to a greater depth than i or 2 
feet. 
As the elevation of the land diminishes, the pure shadscale is gradually 
replaced by an association of greasewood and shadscale. The frontier 
between the two associations is not sharply defined (Pl. XLVII, fig. 2), 
scattered greasewood plants appearing first along gullies or draws and 
gradually, as Great Salt Lake is approached, mingling everywhere with 
the shadscale. This association extends to the edge of the lake, covering 
the summits of the low ridges and hummocks which are interspersed 
among the salt flats. In Tooele Valley greasewood scarcely occurs in a 
pure association, but is practically everywhere mingled with shadscale. 
Between the main greasewood-shadscale area and the salt flats occur 
the grass flats, a nearly level expanse, marshy in places, covered largely 
, with grasses and with a species of Chrysothamnus. (Pl. XLVIII, fig. 3.) 
1 Near the present margin of the lake basinlike areas are found, many 
of which are doubtless under water at times. (Pl. XLHI, fig. 1; PL 
XLVIII, fig. 1.) The larger of these appear in summer as bare expanses 
covered with a glistening crust of white salts. Near their margins, 
however, and often covering the entire surface of the smaller depressions 
certain very salt-resistant plants occur, either scattered over the other¬ 
wise bare ground or forming rather dense colonies. The most important 
of these plants are Allenrolfea occidentalis (Pl. XLVIII, fig. 1), which is 
most at home on the slightly higher margins of the basins, and two 
species of glasswort (Salicornia)—one perennial (S. utahensis) (Pl. 
XLVIII, fig. 2), the other annual ( 5 . rubra). 
