LOCATION PILLARS CATentative Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Pachic Haploxerolls
TYPICAL PEDON: Pillars loam, on a west-southwest facing, linear, 16 percent slope under live oak and understory shrubs and grasses at an elevation of 1,000 meters (3,280 feet). (Colors are for dry soil unless otherwise noted.)The surface is covered by approximately 40 percent gravel.
A1-- 0 to 12 centimeters, (0 to 5 inches); dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; loose, very friable, nonsticky, nonplastic; common fine roots throughout; common fine tubular pores; 7 percent gravel; slightly acid (pH 6.1); clear smooth boundary.
A2-- 12 to 53 centimeters, (5 to 21 inches); dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist; moderate medium subangular blocky structure parting to moderate medium granular structure; soft, very friable, nonsticky, nonplastic; common fine roots throughout; many fine tubular pores; 6 percent gravel; moderately acid (pH 6.0); abrupt wavy boundary. (Combined thickness of the A horizon is 25 to 60 centimeters)
Bw-- 53 to 64 centimeters, (21 to 25 inches); yellowish brown (10YR 5/4) sandy loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; 4 percent gravel; slightly acid (pH 6.5); abrupt irregular boundary.
R-- 64 to 70 centimeters, (25 to 28 inches); fractured granitoid bedrock with sandy loam material in the fractures.
TYPE LOCATION: San Bernardino County, California; 790 meters (2,600 feet) east and 550 meters (1,800 feet) south of the NW corner of section 34, T. 2 N., R. 4 W.; 34 degrees, 13 minutes and 2.8 seconds north latitude and 117 degrees, 17 minutes and 10 seconds west longitude; San Bernardino North 7.5 minute quadrangle; UTM 11S 0473647e 3786302n (DTM: NAD83).
RANGE IN CHARACTERISTICS: The soil moisture control sectionis usually dry in all parts from late May or early June until late November or early December, and usually moist in some or all parts the rest of the year. The soils have a xeric moisture regime.
Soil temperature: 17 to 19 degrees C. (63 to 66 degrees F.)
Organic matter: 1 to 3 percent
Surface rock fragments: 30 to 50 percent gravel
Depth to a lithic contact: 50 to 100 centimeters
Control section -
Thickness of the mollic epipedon: 50 to 80 centimeters
Rock fragments: 0 to 10 percent
Clay content: ranges between 8 and 15 percent
A horizon
Value: 3 or 4 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist
Texture of the fine earth: sandy loam or loam
Clay content: 8 to 15 percent
Rock fragments: 5 to 10 percent gravel
Reaction: moderately or slightly acid
Bw horizon
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 3 or 4, dry or moist
Texture of the fine earth: sandy loam or loam
Clay content: 8 to 15 percent
Rock fragments: 2 to 10 percent gravel
Reaction: slightly acid or neutral
COMPETING SERIES: These are the Ignord, Sheridan and Vina series. Ignord soils contain disseminated lime to at least 102 centimeters (40 inches). Sheridan soils have a paralithic contact. Vina soils have C horizons with 15 percent or more rock fragments.
GEOGRAPHIC SETTING: Pillars soils are on mountain side slopes. Slopes range from 15 to 50 percent. These soils formed in residuum from granitoid sources. Elevations range from 760 to 1,065 meters (2,500 to 3,500 feet). The climate is subhumid mesothermal with warm, dry summers and cool, moist winters with some snow. The mean annual precipitation is 381 to 533 millimeters (15 to 21 inches) and the mean annual air temperature is 16 to 18 degrees C. (60 to 64 degrees F.) The frost-free season is 300 to 340 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Walong and Verdemont(T) soils on similar landscape positions. Neither of these soils have a mollic epipedon more than 50 centimeters thick. In addition, Verdemont soils have a fine-loamy particle-size control section.
DRAINAGE AND PERMEABILITY: Well-drained; medium or high runoff; moderate or moderately rapid permeability.
USE AND VEGETATION: Pillars soils are used for recreation, watershed and wildlife habitat. Some areas are used for homesites. The present vegetation is mainly live oak and understory shrubs and grasses.
DISTRIBUTION AND EXTENT: Lower elevations of inland mountain ranges of San Bernardino, Riverside and San Diego counties, southern California. MLRA 20. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES PROPOSED: San Bernardino County, California, San Bernardino National Forest, Private Land Soil Survey Update Project, 2004. The name is from a landscape feature in the soil survey area.
REMARKS: Diagnostic horizons and features recognized in the profile are:
1. Mollic epipedon: 0 to 53 centimeters (A1 and A2 horizons)
2. Lithic contact: the zone beginning at 64 centimeters (R horizon)
3. Particle-size control section: 25 to 64 centimeters (part of the A2 and Bw horizons)