LOCATION ELPALOALTO CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Pachic Haploxerolls
TYPICAL PEDON: Elpaloalto clay loam, on a north west facing 2 percent slope under a cover of oaks shrubs and redwood mulch at an elevation of 68 feet. When described the soil was moist throughout. (Colors are for dry soil unless otherwise noted).
Oi--0 to 8 inches, (0 to 21 cm); very dark grayish brown (10YR 3/2) exterior slightly decomposed plant material, very dark brown (10YR 2/2) exterior moist; weak fine granular and weak medium granular structure; loose, loose, nonsticky, nonplastic; many fine irregular and many medium irregular pores; neutral, pH 6.7 by pH meter 1:1 water; abrupt smooth boundary. (0 to 4 centimeters thick)
A--8 to 17 inches, (21 to 42 cm); brown (10YR 4/3) broken face clay loam, very dark brown (10YR 2/2) broken face moist; 27 percent clay; moderate coarse subangular blocky and moderate medium subangular blocky structure; hard, firm, , moderately sticky, moderately plastic; common very fine roots; many very fine irregular pores; 10 percent rounded indurated 2 to 75 millimeter mixed rock fragments; slightly acid, pH 6.3 by pH meter 1:1 water; abrupt smooth boundary. (10 to 50 centimeters thick)
Bw1--17 to 26 inches, (42 to 65 cm); brown (10YR 5/3) broken face silty clay loam, very dark brown (10YR 2/2) broken face moist; 38 percent clay; moderate coarse subangular blocky and moderate medium subangular blocky structure; very hard, very firm, very sticky, very plastic; common very fine roots; common fine irregular and common very fine tubular and many very fine irregular pores; neutral, pH 6.7 by pH meter 1:1 water; gradual smooth boundary. (19 to 60 centimeters thick)
Bw2--26 to 35 inches, (65 to 90 cm); brown (10YR 5/3) broken face silty clay loam, very dark brown (10YR 2/2) broken face moist; 39 percent clay; moderate medium subangular blocky structure; very hard, firm, very sticky, very plastic; few coarse roots and few very fine roots; many very fine irregular and common very fine tubular pores; neutral, pH 6.9 by pH meter 1:1 water; gradual smooth boundary. (25 to 45 centimeters thick)
Bw3--35 to 47 inches, (90 to 120 cm); brown (10YR 5/3) broken face silty clay loam, very dark grayish brown (10YR 3/2) broken face moist; 39 percent clay; moderate medium subangular blocky structure; very hard, friable, very sticky, very plastic; few medium roots and few coarse roots; many very fine irregular and common very fine tubular pores; neutral, pH 7.1 by pH meter 1:1 water; clear smooth boundary. (0 to 58 centimeters thick)
Bw4--47 to 71 inches, (120 to 181 cm); brown (10YR 5/3) broken face silty clay loam, very dark grayish brown (10YR 3/2) broken face moist; 39 percent clay; moderate medium subangular blocky structure; very hard, friable, very sticky, very plastic; few medium roots and few coarse roots; many very fine irregular and common very fine tubular pores; neutral, pH 7.0 by pH meter 1:1 water; clear smooth boundary. (0 to 51 centimeters thick)
C--71 to 94 inches, (181 to 240 cm); brown (7.5YR 4/3) broken face silty clay loam, very dark brown (7.5YR 2.5/3) broken face moist; 33 percent clay; weak fine subangular blocky structure; very hard, firm, very sticky, very plastic; few fine roots; common fine irregular and many very fine irregular pores; neutral, pH 7.3 by pH meter 1:1 water;
TYPE LOCATION: Santa Clara County, California, El Camino Park, Palo Alto, plant bed area along El Camino Real, north of park entrance, north of large oak tree., in a non-sectionalized area of Township 6S, Range 3W, UTM zone 10, Northing 4144613, Easting 573509 NAD83. U.S.G.S Quad: Palo Alto, California.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 58 to 62 degrees F. The mean annual air temperature averages 60.3 degrees F., mean winter air temperature averages 50.9 degrees F., mean summer temperatures average 69.1 degrees F. and the difference between mean winter and mean summer averages 18.2 degrees F. The soil moisture control section is dry in all parts from about May 1 to November 1 (about 180 days). The particle size control section, 25 to 100 centimeters, averages 27 to 40 percent clay. Rock fragments range 0 to 10 percent rounded rock fragments, mostly gravel size. Mineralogy is smectitic based on lab data.
The A horizon dry color is 10YR 4/3, 4/2, 3/2; 2.5Y 5/3, or 5/2. Moist color is 10YR 3/3, 2/2; 2.5Y 3/2, or 3/1. Organic matter ranges from 1 to 4 percent to a depth of 17 centimeters. Texture is silt loam, sandy clay loam, clay loam or silty clay loam. Clay content ranges from 20 to 35 percent. Rock fragments range from 0 to 10 percent and are gravel size. Reaction ranges from 5.6 to 7.3.
The Bw horizon dry color is 10YR 6/3, 5/3; 2.5Y 5/3, or 5/2. Moist color is 10YR 4/3, 3/3, 3/2; 2.5Y 4/2, or 3/1. Texture is silty clay loam, clay loam or silt loam. Clay content ranges from 27 to 40 percent. Rock fragments range from 0 to 2 percent and are gravel size. Reaction ranges from 5.6 to 8.4.
The C horizon dry color is 10YR 6/4, 6/3, 5/4, 4/4; or 7.5YR 4/3. Moist color is 10YR 4/4, 4/3, 4/2; or 7.5YR 2.5/3. Texture is silty clay loam or loam. Clay content ranges from 27 to 40 percent. Rock fragments range from 0 to 2 percent and are gravel size. Reaction ranges from 5.6 to 8.4.
COMPETING SERIES: These are the Merced soils. Merced soils are calcareous.
GEOGRAPHIC SETTING: Elpaloalto soils are on floodplains and alluvial fans. Slopes are 0 to 2 percent. These soils formed in alluvium weathered from mixed rock sources. Elevation is 50 to 250 feet. Mean annual precipitation is 14 to 20 inches. The mean annual temperature is 58 to 60 degrees F. Frost free season is 275 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Still and Hangerone soils. The Still soils are on floodplains and alluvial fans and have fine-loamy particle size control sections and the Mollic epipedon is less than 20 inches thick. The Hangerone soils are in basins and have fine an aquic moisture regime.
DRAINAGE AND PERMEABILITY: Well drained; moderate runoff; moderately slow permeability. Flooding is controlled by dams on streams, channelization and levees in some areas. Most areas have subsided several feet due to historic over drafting of ground water.
USE AND VEGETATION: These soils are used for urban uses, industrial, commercial office and residential. Native vegetation was oaks and annual grasses and forbs.
DISTRIBUTION AND EXTENT: These soils are moderately extensive and are mapped in Major Land Resource Area: 14 -- Central California Coastal Valleys
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Santa Clara County, California. Source of name from large redwood tree.
REMARKS:
Particle Size Control Section for this pedon: 10 to 39 in. (25 to 100 cm)
Diagnostic horizons and features recognized in this pedon are:
Mollic Epipedon: 0 to 60 inches
The soil moisture control section is dry in all parts from about May 1 to November 1 (about 180 days).
Pedon Notes: 05ca085641227
ADDITIONAL DATA:
NSSL Lab Pedon #: 07N0675