58 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1910. 



waterways characteristic of tlie series. It is usually well drained, 

 but subject to overflow. The areas were originally rather heavily 

 wooded, but are now for the most part cleared. iScattered oaks occur 

 through the fields, and cottonwood, willow, and grapevines form 

 strips of woodland along the drainage ways. 



The Sacramento silty clay loam is wholly alluvial and owes its 

 origin to the sediments deposited by the Sacramento River under 

 conditions favoring the .segregation of its finest particles. 



For many years it has been devoted to grain farming, and still 

 yields profitable returns. Small areas of dry-farmed alfalfa also 

 occur. 



The soil is admirabl}' adapted to sugar beets and its entire extent 

 could be devoted to this crop with irrigation. Alfalfa, truck, hops, 

 and various fruits are likewise suitable crops for production with 

 irrigation. 



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

 of the soil and subsoil of this type : 



Mechanical analyses of Sacramento silti/ clay loam. 



RIVKRWASH. 



Riverwa.sh is a nonagricultiiral type of very coarse texture, largely 

 composed of waterworn gravel, with coarse sand and some finer sedi- 

 ments in varying quantities. It is leachy and incoherent in structure. 



Riverwash occupies low-lying flood-swept areas, strips or islands 

 along the Sacramento River, and similar small areas in the beds of 

 lateral streams. The principal body found outside the flood plain 

 of the Sacramento lies in the gravelly bed of Thomas Creek. 



Riverwa.sh usually has an uneven surface and is subject to erosion 

 or reworking at frequent intervals. The water table lies near the 

 surface, and upon areas not recently disturbed cottonwood and willow 

 make rapid growth. As a usual thing the tj^pe presents a very 

 barren appearance. 



This type is of course entirely alluvial in origin, most of its mate- 

 rial being rolled into position during floods. Similar materials un- 

 derlie some of the heavier alluvial types. 



ROUGH STONY LAND. 



As the lower slopes of the Lassen Peak Range approach the area 

 from the easi (lu-y give way to an elevated dissected plain of vol- 



