Established Series


The Pollasky series consists of moderately deep, well drained, moderately coarse textured Regosols formed in the residuum from softly to moderately consolidated arkosic sediments. They occur on undulating to steep dissected terraces under annual grasses and forbs. They have brown, slightly acid sandy loam A horizons and pale brown to yellowish brown, slightly acid to neutral, sandy loam C horizons abruptly overlying consolidated granitic sediments. Pollasky soils occur in the same area as Whitney, Cometa, Rocklin, and Montpellier soils. They are similar to the Whitney, Trigo, and Kettleman soils. The Whitney and Trigo soils have formed from the same or similar parent rock. The Whitney soils have minimal Bt horizons. The Trigo soils are shallow (<20") soils with slightly acid to neutral upper A horizons and medium acid lower A horizons abruptly overlying softly consolidated sediments. Kettleman soils are calcareous throughout, medium textured, and developed on sandstones and shales. Pollasky soils occur at elevations below 500 feet to semiarid mesothermal climate having a mean annual precipitation ranging from about 9 to 16 inches with hot, dry summers and cool, moist winters. The average January temperature is about 45 degrees F.; the average July temperature is about 81 degrees F.; and the mean annual temperature is about 62 degrees F. The average frost-free season ranges from about 250 to 300 days. The Pollasky series is mapped along the eastern edge of the San Joaquin Valley of California where it is moderately extensive.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid, thermic Typic Xerorthents

TYPICAL PEDON: Pollasky sandy loam. Site relatively undisturbed under annual grass and for cover; slope, 15 percent; aspect, northwest; elevation, 400 feet.

A11--0 to 3 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 3/3) when moist; moderate medium and fine granular structure; slightly hard, very friable; abundant very fine roots; many medium interstitial pores; slightly acid (pH 6.5); abrupt wavy boundary. 0 to 4 inches thick.

A12--3 to 8 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 3/3) when moist; massive; hard, friable; abundant very fine roots; many very fine and medium tubular pores; slightly acid (pH 6.3); abrupt smooth boundary. 4 to 5 inches thick.

C1--8 to 34 inches; pale brown (10YR 6/3) sandy loam, dark brown (10YR 4/3) when moist; massive; hard, friable; plentiful very fine roots; many medium and very fine tubular pores; slightly acid (pH 6.4); clear wavy boundary. 24 to 26 inches thick.

C2--34 to 39 inches; light yellowish brown (10YR 6/4) sandy loam, dark brown (10YR 4/3) when moist; massive; hard, friable; very slightly sticky; few very fine roots; many fine and very fine interstitial pores, common fine tubular pores; many thin clay films on tubular pore faces; neutral (pH 7.1); abrupt wavy boundary. 1 to 5 inches thick.

R--39 inches +; light brown (7.5YR 6/4) or light yellowish brown to very pale brown (10YR 6/4 - 7/4) moderately consolidated sandy, granitic sediments, dark yellowish brown (10YR 4/3 - 4/4) or dark brown (7.5YR 4/4) when moist; massive; very hard, very firm; very few, very fine random tubular pores; many feet thick.

RANGE IN CHARACTERISTICS: The dry surface soil color ranges from brown to pale brown (10YR 5/3, 6/3). When moist the colors are brown to dark brown, commonly dark brown (10YR 3/3, 4/3, 5/3). Surface textures are commonly sandy loams and fine sandy loams, but may range in places to coarse sandy loam and loam. Subsurface textures are the same as the surfaced textures. The control section (10" - 30") contains less than 18 percent clay. At undisturbed sites the A1 horizon is often subdivided into a thin surface layer having a granular structure, and an underlying horizon having a massive structure. Where cultivated or trampled by grazing animals the surface granular structure is destroyed and the A horizon becomes massive throughout. The thin granular surface horizon has a distinctly higher organic matter content than the remainder of the profile. Surface soil consistence ranges from slightly hard and very friable to hard and friable. Surface soils are seldom, if ever, sticky or plastic. The dry C horizon colors are similar to those for the surface soils, but may have a slightly higher value. They range from brown to pale brown or light yellowish brown (10YR 5/3, 6/3, 6/4). Moist colors are usually dark brown or yellowish brown, but may be light yellowish brown in places (10YR 4/3, 4/4, 6/4). C horizon is massive, and consistence hard when dry and friable when moist. In places it is slightly hard and very friable, or may be very slightly sticky when wet. The C horizon grades abruptly or clearly into the moderately consolidated arkosic sediments that constitute the parent rock. The parent rock is either brown to light yellowish brown, medium sandy material that is well compacted or weakly cemented; or light gray, well compacted fine sands, very fine sands and silts.

GEOGRAPHIC SETTING: Undulating to hilly or steep dissected alluvial terrace lands. Slopes range from about 3 to 35 percent, but are commonly about 12 to 20 percent.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to rapid. The permeability of the A and C horizons is moderate, while the permeability of the R horizon is moderately slow to slow. Perched subsurface saturation above the R horizon from seasonal rainfall or sprinkler irrigation is seldom, if ever, encountered except in associated swales.

VEGETATION: Annual grasses and forbs.

USE: Annual range and dry farmed small grain, usually barley. Limited sprinkler irrigated pasture.

DISTRIBUTION: Eastern parts of the San Joaquin Valley, California, mainly in alluvial terrace lands formed by the major rivers draining the western slope of the Sierra Nevada Mountains.

TYPE LOCATION: 2,200 feet southeast of the junction of Willow Avenue and Friant Road to Fresno County, California at the E 1/4 cor., NE 1/4, SE 1/4 Sec. 1 T. 12 S., R. 20 E., MDB&M.


SERIES PROPOSED: Eastern Fresno Area, 1963. Name taken from former name of the town of Friant, Fresno County, California.

REMARKS: This soil has been mapped with the Whitney soils in other areas. The latter soils are now defined as having minimal Bt horizons. The two common types of the Pollasky soils, sandy loam and fine sandy loam, are associated respectively with the medium sandy parent rock and the fine sandy to silty parent rock. Throughout moist of the extent of these soils the sandy parent rock overlies the finer textured parent rock. The surface patterns of the two common soil types are dependent upon the patterns of exposure of the two rock types. These in turn are dependent upon the degree and extent of the terrace land dissection. Some Pollasky fine sandy loams are formed from similar but younger compacted sediments underlying younger alluvial terraces and exposed to weathering by local dissection.

OSED scanned by SSQA. Last revised by state on 4/64.

National Cooperative Soil Survey