24 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1910. 



BEDDING GRAVELLY SANDY LOAM. 



The Redding gravelly sandy loam has a considerable range of topo- 

 graphic features, giving the soil a variable agricultural vaJue. Typi- 

 cally it consists of a light-red to a red sticky sandy loam of rather 

 uniform texture but uncertain depth, carrying medium to large quan- 

 tities of gravel. This coarse gravelly material was all originally of 

 well-defined water worn character, but the processes of weathering 

 have at this time reduced quantities of it to a snbangular state. 

 These fragments occurring with cobbles of rounded surfaces, coarse 

 sand, and quartz pebbles give the surface material a rather more 

 tillable structure than it would otherwise possess. This gravelly 

 material often accumulates in surface depressions or on eroded slopes, 

 and at all times a slight erosion of soil material renders the immediate 

 surface more gravelly than the underlying layers. The fragments 

 seldom attain a size sufficient to interfere with cultivation. 



At a depth which varies from 12 to 24 inches the surface soil 

 grades sharply into an exceedingly tenacious red clay loam or heavy 

 loam that is practically free from gravel. It is always compact and 

 lias a tendency to crack into rough cubes upon exposure. It some- 

 times carries small quantities of coarse sand, but even under this con- 

 dition loses little of its compact character. This subsoil, of great 

 water-holding capacity, seldom extends to a depth of more than 4 

 feet, being usually underlain at variable depths by a true ferruginous 

 hardpan of cemented clay particles. The hardpan layer is from 1 to 

 (') inches thick, impervious to water, and impenetrable to plant roots, 

 and rests upon great masses of indurated gravel, silt, and sands. 

 These occur in partial!}' assorted layers extending to great depths and 

 of little value for root development, even though rendered penetrable 

 by blasting. In those cases where the hardpan laj^er is absent, the 

 subsoil grades into the massive bodies of semicemented waterworn 

 material and the tyj^e is perhaps a little better agriculturally by rea- 

 son of the slight disintegration of the mass at its point of contact with 

 the soil. 



This type is confined to several bodies in the northern part of the 

 area. These occur as the southern extremity of the low rolling hills 

 bordering the Iron Canyon section of the Sacramento Kiver and giv- 

 ing way near Red Bluff to the more level valley plains. The material 

 of which this type consists is a Pleistocene alluvial product, deposited 

 to great depths over a considerable section, the present remnants of 

 which lie mainly north of the Red Bluff' area. 



The surface of this type is gently to sharply rolling and north of 

 lied Bluff nnich dissected, with excessive drainage and a general 

 topography unfavorable to agi'iculture. A natural growth of upland 

 oaks, ceanothus. and inan/aiiita cover these latter sections. Those 



