Soil Survey of the Ventura Area, California (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ...loam: PI.EASANTON GBAVEIXY SANDY MAM. The surface 12 to 18 inches of the Pleasanton gravelly sandy loam consists of a loose, friable, gravelly, sandy loam relatively high in fine sand. The color is prevailingly brown, but ranges to dark brown. It contains a fair amount of organic matter, but the structure is so open and porous that the power of the soil to hold moisture is low. In spots the texture grades toward a gravelly fine sandy loam, but the difference is of no agricultural importance. Large rounded waterworn cobbles and bowlders are scattered over most of the type. Areas of excessive stone content are indicated on the soil map by symbols. The surface soil grades imperceptibly into the subsoil. The color of the latter ranges from brown to reddish brown, and the texture is slightly heavier, closely approximating a loam. The structure is much more compact than in the soil, and the power to hold moisture is greater, but water and roots penetrate it without much difficulty. The subsoil contains rounded bowlders derived from sedimentary rocks. The change from subsoil to substratum is not sharp. Ordinarily it takes place between the depths of 4 and 6 feet. The substratum resembles the subsoil in color, but normally contains more sandy material and bowlders, is less compact, and has a low moistureretaining power. It is usually many feet in depth, but in places it forms a veneer over shales of the sedimentary hills. The Pleasanton gravelly sandy loam is confined to a few areas in the northwestern part of the survey. Most of these lie in the Ojai Valley, but there is one in the western end of the Santa Ana Valley. The soil is formed from old-alluvial deposits and lies at considerable elevations above the stream bottoms, from which it is separated by steep bluf...