CALIFORNIA VALLEY SOILS DESCRIBED 



29 



supplemented by irrigation, but mostly a free-working, fairly re- 

 tentive, light loam, very satisfactory for some kinds of fruits. 



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 up- 

 land 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 irrigation has been 

 made. Though its summer 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 produc- 

 tiveness of tree and vine. These plains loams vary in appearance, 

 and are from this fact locally named, "reddish loam," "white ash," 

 and "sand hill." All are distinctly calcareous. Even in the case 

 of the latter, which is the lightest and made of almost 90 per cent 

 of inert sand, it is so deep and has its plant food in such highly 

 available condition that it is producing very large crops of fruits 

 where there is no rise of the bottom water to prevent root penetra- 

 tion. In the foothills of the Sierra Nevada there are some loose 

 loams of light color resulting from the decomposition of granite, but 

 they are as a rule inferior to the red foothill soils, which are more 

 clayey, and will be mentioned among the clay loams later. 



The soils prevailing in the valley of Southern California, from 

 Redlands at its head to Los Angeles at its opening out toward the 

 sea, consist chiefly of granitic sand, which at some points on the 

 slopes forms the soils exclusively, but everywhere constitutes a 

 prominent ingredient of the valley and mesa lands. These mesa 

 lands are conspicuous for their orange-red tint, and the red sandy 

 loam of which they are composed, to depths varying from ten to as 

 much as eighty feet, is evidently the choice soil for orange culture. 

 It is manifest that at some remote epoch it filled the entire valley. 

 Of the middle portion much has been washed away, but islands of 

 it form red-land tracts of greater or less extent all over the region, 

 traversed by and more or less commingled with the gigantic wash 

 from the valleys and canyons of the Sierra Madre. The latter fre- 

 quently consists largely of gravel, and were it not for the luxuriant 

 natural vegetation borne by these gravel beds, few would have 

 thought of devoting them to the costly experiment of orange plant- 

 ing, which nevertheless, has proved eminently successful even on 

 these unpromising-looking masses of debris. In the upper valley 

 (San Bernardino Valley proper) the red loam is conspicuous, and 

 gives its name to the flourishing city and citrus district of Redlands, 

 on the terminal slope ; but the heavy flow of water from the upper 

 canyons, notably from that of the Santa Ana River, has scoured it 

 out of the valley itself, and left there, at least on the northern por- 

 tion, gray and blackish granitic loams of great depth and produc- 

 tiveness, underlaid, and therefore underdrained, by the enormous 

 gravel beds that hold the artesian water of this favored region. 



The reddish mesa soils prevail through the smaller Southern Cali- 

 fornia valleys as well, and are similar in character, as they are de- 

 rived from similar geological formations. 



