30 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1910. 



size well located to make it a soil of great j^ossible value. The sur- 

 face lends itself readily to irrigation methods and its naturall}' well- 

 drained character will make it, in all but its most gravelly phases, 

 an important factor in the success of any irrigation enterprise. 

 Peaches, berries, almonds, apricots, and other crops, including melons 

 and alfalfa, will thrive on this soil, which needs only a slightly 

 greater application of water than the Tehama silt loam. Intensive, 

 small fann industries are not jx)s.<ible without irrigation. 



The following table gives the average results of mechanical analj^ses 

 of the soil and a single analysis of the subsoil of this type : 



Mechanicdl analyses of Tehama gravelly loam. 



TEHAMA SILT LOAM. 



The Tehama silt loam is one of the most important types of the 

 area. It is a comparatively uniform type in its principal character- 

 istics. The soil consists of a compact yellowish-brown or reddish- 

 yellow silt loam, with a depth varying from 10 to 20 inches. In 

 limited areas the surface soil is gritty or even gravelly, being at such 

 times influenced by present washes or indistinct long-abandoned 

 drainage ways, slightly elevated by the deposition of material and 

 now shown only by meandering streaks of gravelly soil. The sub- 

 soil, also fairly uniform, is a tenacious brown silty clay loam of 

 impervious structure to G feet deep. The material cracks upon ex- 

 posure and has an adobe tendency. When variation occurs in the 

 subsoil it is found to accompany the change in the surface soil occa- 

 sioned by the slight rew^orking by water. In these cases the subsoil 

 in small areas may be quite gravelly. Extensive beds of compact 

 silt, sand, and gravel usually underly this type below 6 feet. 



In its occurrence the Tehama silt loam uniformly occupies eleva- 

 tions slightly below the Kcdding and Corning series, being in most 

 cases separated from them by pronounced slopes or terraces of sev- 

 eral feet. From the lower lying soils of the Maywood, Elder, and 

 Sacramento series it is again separated by terraces, often pronounced, 

 along the alluvial flood plain of the Sacramento River. Practically 

 confined to the west side of the river and occupying regions of inter- 

 mediate elcviition. tlie type occurs as almost uniform plains of gentle 

 slope and barren character, except for a very sparse growth of grass 

 and a few trees along small streams and the lower terrace lines. Its 



