AGRICULTURE AND SOILS OF CALIFORNIA. 483 
qualifications and care on the part of the observer to insure useful re- 
sults. There are, however, some general features developed on a large 
scale in the more thickly settled parts of the State, a brief summary 
of which may find a place here. ; 
It is well known that the main axis of the Sierra Nevada is formed 
by granitic rocks, which in the northern portion of the range, as well as 
on the slopes, are usually overlaid by clay slates and shales, forming 
the proverbial “ bed-rock” of the gold-placers and gravel-beds. The 
soil derived either directly from the granites or from the older portion 
of the slates—in other words, the gold-bearing soil of the Sierra slope—is 
an orange-colored (commonly called ‘‘red”) loam, more or less clayey or. 
sandy according to location, and greatly resembles, on the whole, the 
older portion of the “yellow loam” subsoil of the Gulf States. Of 
course it contains much more of coarse materials in the shapé of unde- 
composed rock, and its sand-grains are sharp instead of rounded. It is 
the predominant soil of “the foot-hills,” and where ridges extend from 
these out into the Great Valley they are usually characterized by the 
red tint, which gradually fades out as the ridges flatten into swales in 
their approach to the San Joaquin and Sacramento Rivers, being lost 
in the gray or black of the “adobe,” or the buff of the river-sediment 
soils. lis admixture is everywhere, I believe, found to be advantageous 
to the other soils; and in the foot-hills themselves it proves to be highly 
productive, as well as durable, easy of tillage, and what is termed a 
“warm” soil. The rocks of the lower slope of the Sierra, but more 
especially those of the Coast Range opposite, are predominantly of a very 
clayey character, soft gray clay shales and laminated clays alternating 
with ledges of soft clay sandstone and brittle hornstone. Their mechan- 
ical and chemical decomposition results, therefore, in the formation of 
gray, buff, or sometimes almost white clay soils, which occupy the hill- 
sides and higher portions of the valleys, while in the lower portions the 
admixture of vegetable matter, especially in the presence of a compara- 
tively large amount of lime, causes them to appear dark, and often coal- 
black. These soils constitute the “ adobe,” so often mentioned in con- 
nection with California agriculture. They are substantially the same, 
both as to tilling qualities and chemical composition, as the prairie soils 
of the Western and Southern States. Like these, they are rich in plant 
food, durable, and strong, yielding the highest returns of field crops in 
favorable seasons and under good culture, but sensitive to extremes of 
wet or dry seasons, and of course more in cultivation, as well as more 
liable to crop failures, than lighter soils. During the dry season the 
adobe soil, unless it has been very deeply and thoroughly tilled, becomes 
conspicuous by the wide and deep gaping cracks which traverse it in all 
directions, sometimes to adepth of several feet, precisely as in the “hog- 
wallow prairies” of the Southwestern States. Of course the effect of 
rains is here also similar in causing a bulging up of the masses between 
the cracks when the material which has fallen into the latter expands 
forcibly on wetting. Hence the “hog-wallow” surface is as familiar in 
California as in Texas; and the fact that a traveler outside of the Sierras 
in the dry season is rarely out of sight of some such land is eloguent as 
to the wide prevalence of the “‘adobe.” On the steep hillsides of the 
Coast Range the sun-cracks aid in giving foothold to stock; and during 
the rainy season the water running into them to the bed-rock causes num- 
berless land-slides, such as gave rise to the memorable case of Hyde vs. 
Morgan. As it is well ascertained that ata former geological period 
the entire interior valley, as well as the bay of San Francisco, was 
fresh-water lake basins, the bulk of the adobe soil would seem to repre- 
