LOCATION SAPWI CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Pachic Argixerolls
TYPICAL PEDON: Sapwi loam, on the side of a mountain at an elevation of 780 feet. (Colors are for dry soil unless otherwise noted).
Oe--0 to 1 inches (0 to 2.5 centimeters); oak leaves and twigs.
A--1 to 4 inches (2.5 to 10 centimeters); grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak very fine subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; common very fine roots; few very fine interstitial pores; 5 percent very fine pararock fragments; neutral (pH 6.6); clear smooth boundary. (2 to 5 inches thick)
Bt1--4 to 11 inches (10 to 28 centimeters); brown (10YR 5/3) stony clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, sticky and slightly plastic; common very fine through very coarse roots; common very fine through coarse tubular pores; common very thin clay films on ped faces and lining pores; 5 percent gravel, 5 percent cobbles, 5 percent stones; neutral (pH 6.7); clear wavy boundary. (4 to 15 inches thick)
Bt2--11 to 24 inches (28 to 60 centimeters); brown (10YR 4/3) stony clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, friable, sticky and slightly plastic; common very fine through very coarse roots; common very fine through coarse tubular pores; common very thin clay films on ped faces and lining pores; 5 percent gravel, 5 percent cobbles, 5 percent stones; neutral (pH 6.7); clear wavy boundary. (10 to 30 inches thick)
Bt3--24 to 38 inches (60 to 95 centimeters); mixed matrix 85 percent light yellowish brown (10YR 6/4) and 15 percent grayish brown (10YR 5/2) very stony clay loam, dark yellowish brown (10YR 4/4) and very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, friable, sticky and plastic; common very fine through coarse roots; common very fine through coarse tubular pores; common very thin clay films on ped faces and lining pores; 20 percent gravel, 20 percent cobbles and 20 percent stones; neutral (pH 6.6); abrupt wavy boundary. (8 to 20 inches thick)
R--38 to 39 inches (95 to 98 centimeters); very slightly fractured sandstone.
TYPE LOCATION: Los Angeles, California; about two and a half miles northeast of Leo Carrillo State Beach and Highway 1; 2250 feet south and 2100 feet east of the northwest corner of section 18, T. 1 S., R. 19 W.; Latitude 34 degrees, 4 minutes, 58 seconds north and Longitude 118 degrees, 54 minutes, 48 seconds west; Triunfo Pass Quadrangle.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 62 to 66 degrees F.
Soil moisture: Soil is moist in middle to late November to late June or early July.
Depth to bedrock: 20 to 40 inches (50 to 100 centimeters).
Organic matter content: 2 to 4 percent.
A horizon--10YR 5/3, 5/2, 4/3, 4/2; 10YR 3/3, 3/2, 2/2 moist.
Clay percentage--12 to 27 percent.
Coarse fragments--0 to 15 percent. Some pedons have 15 to 30 percent coarse fragments in the lower part of the horizon.
Bt horizon--10YR 6/4, 5/3, 5/2, 4/3, 4/2; 10YR 4/4, 3/3, 3/2, 2/2 moist.
Texture--Clay loam, loam, gravelly loam, cobbly loam, stony loam, gravelly clay loam, cobbly clay loam, or stony clay loam in the upper part of the horizon, and very gravelly clay loam, very cobbly clay loam or very stony clay loam in the lower part of the horizon.
Clay percentage--18 to 35 percent.
Coarse fragments--5 to 35 percent in the upper part of the horizon, and 35 to 70 percent in the lower part of the horizon.
COMPETING SERIES: These are the Arujo, Botella, Chico, Corona, Elkhorn, Havala, Kawenga, Lockwood, McCoy, Saltcanyon and Tongva soils. Arujo soils are 40 to 60 inches deep to granitic paralithic material, and have a mean summer temperature that differs by greater than 25 degrees F. from the mean winter temperature. Botella, Chico, Corona, Elkhorn, Havala, Kawenga, Lockwood, and Saltcanyon soils are all greater than 60 inches to rock. McCoy soils are 25 to 40 inches to granitic paralithic material and have Bt horizons that are slightly to moderately alkaline. Tongva soils lack very gravelly, very cobbly or very stony textures in the lower part of the argillic horizon, and they have paralithic contacts at 20 to 40 inches.
GEOGRAPHIC SETTING: Sapwi soils are on northerly and easterly facing, concave, side slopes of hills and mountains. These soils formed in residuum and colluvium derived from sandstone. Slopes are 15 to 75 percent. Elevations are 500 to 3000 feet. The climate is characterized by warm, dry summers and cool, moist winters. The mean annual precipitation is 18 to 24 inches, the mean annual temperature is 60 to 64 degrees F., and the frost free season is to 290 to 350 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kawenga (t), Mipolomol (t), Topanga (t), and Zumaridge (t) soils. All these soils are on side slopes of hills and mountains. Kawenga soils are deep and lack R horizons. Mipolomol and Topanga soils are shallow and lack R horizons. Zumaridge soils are shallow to an R horizon and lack argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; low to high runoff; moderate to moderately slow permeability.
USE AND VEGETATION: Wildlife habitat, recreation and building site development. Vegetation is Coast Live oak, poison oak, and miscellaneous forbs and grasses.
DISTRIBUTION AND EXTENT: Ventura County and Los Angeles County, California. The soil is not extensive. MLRA 20.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Los Angeles County, California, 2000.
REMARKS: The series name is from a local American Indian village site. Diagnostic horizons and features recognized in this pedon:
Mollic epipedon--The zone from the soil surface to a depth of about 24 inches (A and Bt1 horizons).
Argillic horizon--The zone from a depth of 4 inches to a depth of about 38 inches (Bt1 and Bt2 horizons).
Lithic contact--The zone at a depth of 38 inches (R horizon)