Northern Valley Loams. 31 
loams, according to the proportion of clay commingled with the 
sand or coarse materials. 
Professor Hilgard has devised the following nomenclature 
of soils based upon their content of clay: Sandy soils, less than 
five per cent of clay; sandy loams, from five to ten per cent; 
ordinary or medium loams, from ten to fifteen per cent; clay 
loams, from fifteen to twenty per cent; clay soils, from twenty to 
fifty per cent of clay. 
The coarse materials are sand grains of various sizes or rock 
particles in various degrees of disintegration. The fine materials 
are clay and rock powder, commonly designated as fine silt. 
Loam soils may result from deposits by flowing water or may 
consist of debris but little removed from local rock disintegra- 
tion. They include a wide variety of materials but agree in the 
possession of striking adaptability to fruit culture. Some of the 
leading instances of such soils may be cited. 
Loams of the Valley Plains——On the east side of the Sacra- 
mento Valley low ridges and swales at right angles to the river’s 
course come in from the foot-hills, forming a gently undulating 
plain with a fall of from fifteen to twenty feet per mile, some- 
times right up to the river channels. Nearly all the soils of the 
east side have a reddish tinge, showing the admixture of the red 
foot-hill soil, and demonstrating, by the way, that all these lands 
are well drained. In cuts ten to twelve feet deep, made by the 
sloughs, the reddish plains loam is seen to reach from six to ten 
feet depth, being then underlaid by gravelly substrata. The width 
of this class of profusely fertile valley land, east and west, varies 
considerably, according to the meanderings of the rivers. Away 
from the water courses, the higher lands of the valleys are 
largely red or yellow loams, sometimes clayey and difficult of 
cultivation unless taken just in the right condition, sometimes 
gravelly and apt to dry out unless the natural water supply is 
supplemented by irrigation, but mostly a free-working, fairly re- 
tentive, light loam, very satisfactory for some kinds of fruit. 
The soils of the San Joaquin Valley have, as a rule, a much 
greater admixture of sand than those of the Sacramento Valley; 
there is also a more distinct subdivision of the valley lands into 
upland or “bench” lands, and lowland or alluvial lands proper. 
Upon the upland or plains soils, especially of Fresno and 
Tulare Counties, wonderful progress in fruit-growing by irriga- 
tion has been made during the last few years. Though its sum- 
mer aspect is most forbidding and almost desert-like in lack of 
vegetation, the application of water has shown exceptional 
quickness of growth, early bearing, and lavish productiveness of 
tree and vine. These plains loams vary in appearance, and are 
from this fact locally named, “reddish loam,” “white ash,” and 
