LOCATION PLUTOS CA

Established Series
Rev. JJN/TDC
12/2022

PLUTOS SERIES

The Plutos series consists of moderately deep, somewhat excessively drained soils that formed in sandy glacial outwash from extrusive igneous rock and volcanic ash. Plutos soils are on outwash plains and fans over fractured basalt lava flows. Slopes are 0 to 30 percent. The mean annual precipitation is about 13 inches and the mean annual temperature is about 48 degrees F.

TAXONOMIC CLASS: Ashy, glassy, nonacid, mesic Vitrandic Xeropsamments

TYPICAL PEDON: Plutos loamy sand-on a slope of 1 percent under juniper, sagebrush, squirrel tail and wild currant at 3,580 feet elevation. (Colors are for dry soil unless otherwise noted. When described (10/4/67) the soil was dry throughout

A11--0 to 3 inches; grayish brown (10YR 5/2) loamy sand, very dark grayish brown (10YR 3/2) moist; single grain; loose; few very fine and fine roots, many fine interstitial pores, 5 percent fine and medium (2 to 30mm) pumice pebbles; moderately acid (pH 5.8); abrupt smooth boundary. (2 to 4 inches thick)

A12--3 to 7 inches; grayish brown (10YR 5/2) loamy sand, very dark grayish brown (10YR 3/2) moist; very weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine, fine and medium roots; few fine tubular and many fine interstitial pores; 10 percent fine and medium (2 to 30mm) pumice pebbles; moderately acid (pH 5.8); abrupt smooth boundary. (3 to 6 inches thick)

AC--7 to 14 inches; light brownish gray (2.5Y 6/2) sand, very dark grayish brown (10YR 3/2) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine, and many medium and coarse roots; many fine interstitial pores; 10 percent fine and medium (2 to 30mm) pumice pebbles; moderately acid (pH 5.8); abrupt smooth boundary. (0 to 10 inches thick)

C--14 to 23 inches; pale brown (10YR 6/3) sand, dark brown (10YR 3/3) moist; massive; soft and slightly hard, very friable, nonsticky and nonplastic; few very fine and fine, and common medium and coarse roots; few fine tubular, and many fine interstitial pores; 10 to 15 percent pebbles; neutral (pH 6.8); abrupt smooth boundary. (9 to 20 inches thick)

IIR--23 to 24 inches; hard basalt that is vesicular, has a high olivine content and is well fractured.

TYPE LOCATION: Siskiyou County, California; south end of Shasta Valley about 11 miles northeast of Weed and about 1 mile north of Haystack Butte; about 2,400 feet east and 200 feet south of the northwest corner of section 26, T.43N., R.4W.

RANGE IN CHARACTERISTICS: Depth to a lithic contact of hard fractured basalt is 20 to 40 inches. The mean annual soil temperature is 48 degrees to 56 degrees F.; the mean January soil temperature is 34 degrees to 37 degrees F.; the mean July soil temperature is 62 degrees to 75 degrees F. The soil temperature exceeds 41 degrees F. from March 15 to December 1 and exceeds 47 degrees F. from April 15 to November 20. The soil between the depths of 12 to 36 inches is dry from mid-July until mid-October and is moist in some or all parts the rest of the year. An O horizon of 1/2 inch to 2 inches thick is common under trees and shrubs. It is assumed that the base saturation is 60 to 75 percent in some part of the upper 10 to 30 inches. The soil is neutral to medium acid. There are 2 to 15 percent fine to coarse (2mm to 4cm) basalt or pumice pebbles.

The A horizon is grayish brown or light brownish gray (10YR 5/2, 6/2; 2.5Y 5/2, 6/2). Moist colors are very dark brown or very dark grayish brown (10YR 2/2, 3/2; 2.5Y 3/2). It is sand or loamy sand. Organic carbon ranges from 0.3 to 0.6 percent.

The C horizon is brown. pale brown, grayish brown, or light brownish gray (10YR 5/2, 5/3, 6/2, 6/3; 2.5Y 5/2, 6/2). Moist colors are very dark brown, very dark grayish brown, or dark brown (10YR 2/2, 3/2, 3/3; 2.5Y 3/2). It is sand or loamy sand.

COMPETING SERIES: These are the Delaney series in the same family and the Deetz and Oosen series in other families. Delaney soils are 40 to 80 inches or more deep, to basalt flow rock. Deetz soils are greater than 60 inches deep and have less than 60 percent base saturation. Oosen soils are greater than 80 inches deep, have frigid soil temperature, and have less than 60 percent base saturation.

GEOGRAPHIC SETTING: Plutos soils are in collapse basins between expansion ridges of basalt lava flows. Slopes are 0 to 30 percent. The soils formed in alpine glacial outwash mixed with volcanic ash and pumice. Elevations are 2,800 to 4,500 feet. Stones and cobbles are scattered over the soil surface occupying less than 0.01 percent of the area. There are rock outcrops of lava flow expansion ridges 1 to 30 feet high and 20 to 150 feet apart. The climate is continental and subhumid with warm dry summers and cold moist winters. The mean annual precipitation is 10 to 16 inches. Snowfall averages 18 to 24 inches. Mean January temperature is 30 degrees to 34 degrees F.; mean July temperature is 65 degrees to 68 degrees F.; mean annual temperature is 46 degrees to 50 degrees F. Frost-free season is 100 to 140 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Louie and the competing Deetz and Delaney soils. Louie soils are 20 to 40 inches deep to a duripan and have a fine-loamy argillic horizon.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained, slow through rapid runoff; rapid permeability. The soil surface is hydrophobic and wets slowly when dry, runoff is medium until it is wetted. High intensity rains cause some erosion and runoff when surface soil is dry.

USE AND VEGETATION: Used mainly for limited grazing in early spring months. Much of it is now subdivided for recreational homes. Only 1 or 2 percent is cultivated. Vegetation consists of western juniper, manzanita, rabbitbrush, sagebrush, bitterbrush, wild currant, skunkbush sumac, squirreltail, prairie junegrass, bluebunch wheatgrass, needlegrass and annual brome grasses. Many small areas are actively eroding by wind and are nearly devoid of vegetation.

DISTRIBUTION AND EXTENT: Plutos soils are in southern Shasta Valley in Siskiyou County, California and may occur in other elevated valley in north-central California and south-central Oregon. They are not extensive and are mapped in complex with Rock outcrop.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Siskiyou County, California. 1978.

REMARKS: Mineralogy and organic carbon data are based on Riverside Laboratory sampling on the closely similar Delaney soils.

OSED scanned by SSQA. Last revised by state on 10/78.

National Cooperative Soil Survey
U.S.A.