SOIL SURVEY OF THE RED BLUFF AREA, CALIFORNIA. 



41 



The Tuscan stony sandj^ loam covers a considerable extent in the 

 eastern part of the area and is locally known as " lava flows." The 

 l^lains which it occupies usually border the Sacramento and Vina 

 series, distinct bluffs or terraces interA^ening. Abrupt ascents again 

 separate it from the Rough stony land. The surface of the region 

 occupied by this type once occurred as an unbroken plain but now 

 is somewhat diversified by stream ways with a general slope toward 

 the river trough of about 50 or 60 feet to the mile. It is entirely 

 treeless, except along these small canyons, and in fact supports 

 nothing but a scant growth of grass suitable only for sheep. 



It consists in part of residual material and, in places, of reworked 

 stream-deposited material. The surface soil is no doubt largely a 

 secondary residual material — the disintegrated product of the great 

 quantities of bowlders and finer material previously mentioned. 



This soil is a nonagricultural type. The very shallow depths 

 available for plant roots, coupled with the unfavorable subsoil con- 

 dition, makes it the jjoorest type of the area. It is hard to foresee 

 the time when, even with irrigation, its present condition will be 

 materially changed. 



The following table gives the average results of mechanical 

 analyses of the soil of this type : 



Mechanical analyses of Tuscan stnnri sanchj loam. 



TUSCAN STONY LOAM. 



The Tuscan stony loam bears strong resemblances to the stony 

 sandy loam of the same series. Typically it consists of from 18 to 

 SO inches of reddish or reddish-brown loam carrying fewer rock frag- 

 ments in the soil body and less burdened with the stony surface accu- 

 mulation than the Tuscan stony sandy loam. It is always underlain 

 at a shalloAv depth, rarely over 30 inches, by the impenetrable mass 

 of cemented volcanic material previously described. As is the case 

 in the stony sandy loam, this underlying material is sometimes ex- 

 posed at the surface. The type is subject to little variation except 

 along lines of contact with the Vina series where gradations some- 

 times occur. 



The type occupies several bodies of medium extent in that section 

 of the area east of the Sacramento River. Its general surface is level 

 to rolling and is marked by meandering drainage depressions with 

 indistinct banks. It is at all times treeless and barren in appearance. 



