48 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1910. 



VINA LOAM. 



The Vina loam consists typically of from '20 to 30 inches of brown 

 or reddi.sh-broAvn smooth-textured loam. In some places the content 

 of silt is higher and the depth of soil greater (G feet or more) than 

 in the typical areas. Generally the soil is underlain at a depth of 

 about 24 inches by gravel beds. These are composed of reworked 

 transported material derived from the indurated subsoil of the Tus- 

 can series or the type may rest directly upon these undisturbed con- 

 glomerate nuisses. Small quantities of waterworn volcanic gravel 

 are also usually present in the typical soil, though onl}^ in exceptional 

 cases in amounts sufficient to influence the tillage or yields. The 

 type is at all times rather friable and well drained. 



The Vina loam occurs in several fan-shaped bodies in the delta of 

 Mill Creek and is practically confined to the region influenced by 

 this stream. The surface is level to gently sloping. Its different 

 bodies are separated by the depressions of actual or abandoned chan- 

 nels of Mill Creek which approach the Sacramento River by diverg- 

 ing courses. Kather abrupt terraces, usually bordering thase depres- 

 sions, form the most pronounced topographic feature of the type. 



The region occupied by the Vina loam was at one time a part of an 

 extensive plain, large portions of which are still occupied by the 

 Tuscan series. Mill Creek, a perennial stream, traverses this j^lain 

 in a small valley until it reaches a point about 2 or 3 miles from 

 the Sacramento River, when its main waterway divides into several 

 small channels, some in present use and others abandoned. The 

 Vina loam occupies the areas lying between these channels. Its sur- 

 face material is the product carried some distances by the stream 

 and intermingled with soil material of the original plain which has 

 been largely removed by erosion. The subsoil, with its variations 

 from loose to cemented gravel, represents the different degrees of 

 reworking to wliich the subsurface layers have been subjected. 



The original vegetation consisted largely of blue oak, with ceano- 

 tiius and cliapnii-al. Parts of the areas are yet covered with this 

 growth. 



Limited areas were cleared years ago and devoted to grain, but its 

 princij):il area did not receive serious attention until the recent irri- 

 gation development in the region occupied by this and kindred types. 

 It constitutes the body of land locally known as the " Park soils." 

 The value of this type without irrigation is small, grain being per- 

 haps the only fro|) ])()ssil)l(» and even this giving Ioav yields. With 

 irrigation and iiilclligciit methods a diversity of crops is possible. 

 The soil, generally speaking, is rather shallow for most irrigated 

 crops, so that its range of adaptation is relatively limited. Alfalfa 

 is not to he iccoiiimended, and the same is true of all the deeper 

 rooted tree fruits, except on those portions where quite a depth of 



