CALIFORNIA VALLEY LOAMS 29 



Professor Hilgard has devised the following nomenclature of soils 

 based upon their content of clay ; sandy soils, less than 5 per cent of clay ; 

 sandy loams, from 5 to 10 per cent; ordinary or medium loams, from 

 10 to 15 per cent; clay loams, from 15 to 20 per cent; clay soils, from 

 20 to 50 per cent of clay. 



The coarse materials are sand grains of various sizes or rock par- 

 ticles 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 disintegration. 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 foothills, forming a gently undulating plain 

 with a fall of from fifteen to twenty feet per mile, sometimes right up 

 to the river channels. Nearly all the soils of the east side have a red- 

 dish tinge, showing the admixture of the red foothill soil and demon- 

 strating, 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 in 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 supple- 

 mented by irrigation, but mostly a free-working, fairly retentive, 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 irrigation has been 

 made during the last few years. 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 productiveness 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 penetration. 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. 



