Clay Sorls. 35 
Clay Loams of the Foot-hills and Valley Border.—The soils 
of the foot-hills of the Sierra Nevada, throughout its course 
along the great valley, vary from a moderately clayey loam to 
a heavy, though not uncommonly gravelly, often orange-red 
clay. This character seems to be sensibly the same, whether the 
soil be derived from the decomposition of the ancient slate bed-. 
rock or directly from the dark-colored granites, thus creating 
a presumption that the two rocks are closely related. The soils 
are highly charged with iron to the extent of from seven to over 
twelve per cent, which being finely divided, imparts to them the 
intense orange-red tint. The soils of the foot-hills agree with 
the soils of the valley in having a good precentage of lime, while 
the supply of potash and phosphates, as well as of organic mat- 
ter, is smaller, and sometimes low, though never apparently 
inadequate for present productiveness, in the presence of so 
much lime. 
Along the base of the foot-hills of the Sierra there is in 
Fresno, Tulare, and part of Kern County, a belt of reddish or 
brown loam soils, corresponding to those similarly located in 
the Sacramento Valley, but generally more clayey, and hence 
frequently designated as adobe by contrast with the very sandy 
soils of the valley at large, although properly they should be 
classed simply as clayey loams. This belt is eight to ten miles 
wide in middle Tulare County, and narrows to the north and 
south. Here these lands have a gentle slope of ten to twenty 
feet per mile from the base of the foot-hills, and appear to be 
underlaid at a depth of twelve to fifteen feet by water-bearing 
gravel. The soil is a reddish, more or less sandy, loam, chang- 
ing little in its aspect for several feet. Its adaptation to fruit is 
shown by the products of the Porterville region. 
CLAY SOILS. 
Thus far a very small area of true adobe* soil has been 
employed in horticulture. There is a great difference in the 
character of what is known as adobe in different localities. Its 
color varies, as the popular terms “black waxy,” “black,” 
“brown,” and “gray” adobe indicate. Its physical condition and 
chemical composition also vary greatly. The black adobe of 
the east side of the Sacramento Valley is easily tilled as com- 
pared with the gray adobe on the west side, which is very refrac- 
tory and often largely impregnated with alkali. To render soil 
of adobe character useful for fruit growing, this tendency to dry 
out and crack, thus allowing evaporation from below as well as 
* This name has been erroneously applied to the loam commonly used in the construction 
et gto houses. Agriculturally, it means ‘‘a heavy clay soil,” such as could not be used in 
uilding. 
