LOCATION UNISTAN CAEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, thermic Lithic Haploxerolls
TYPICAL PEDON: Unistan gravelly clay loam, on a south east facing 20 percent slope under a cover of annual grasses and forbs at an elevation of 269 feet. When described the soil was moist throughout. (Colors are for dry soil unless otherwise noted).
A--0 to 2 inches, (0 to 6 cm); brown (10YR 4/3) broken face gravelly clay loam, dark brown (10YR 3/3) broken face moist; 37 percent clay; moderate fine granular structure; slightly hard, very friable, moderately sticky, moderately plastic; many very fine roots; few very fine tubular pores; 30 percent clay films on all faces of peds; 15 percent angular strongly cemented 2 to 75 millimeter basalt fragments; slightly acid, pH 6.4 by pH meter 1:1 water; clear smooth boundary. (thickness of the A horizon is 6 to 9 centimeters)
Bw--2 to 11 inches, (6 to 28 cm); dark brown (10YR 3/3) broken face very gravelly clay loam, very dark grayish brown (10YR 3/2) broken face moist; 38 percent clay; weak medium subangular blocky structure; slightly hard, very friable, moderately sticky, moderately plastic; common very fine roots; many very fine interstitial pores; 5 percent angular strongly cemented 75 to 254 millimeter basalt fragments and 40 percent angular strongly cemented 2 to 75 millimeter basalt fragments; slightly acid, pH 6.3 by pH meter 1:1 water; abrupt smooth boundary. (thickness of the Bw horizon is 11 to 41 centimeters)
R--11 to 13 inches, (28 to 34 cm); strongly cemented basalt bedrock.
TYPE LOCATION: Santa Clara County, California, Stanford University Academic Preserve, east of large basalt quarry, east over ridge on south east slope., unsectionalized of Section , Township 6S, Range 3W, 4139648 UTM Northing, 574274 UTM Easting, Zone 10, UTM Zone 10 NAD83 - U.S.G.S Quad: Palo Alto, California.
RANGE IN CHARACTERISTICS: Depth to basalt is 7 to 19 inches, (17 to 48 cm). The mean annual soil temperature is 58 to 62 degrees F. The particle size control section averages 20 to 45 percent clay, with 15 to 40 percent gravel size fragments and 5 to 50 percent cobble size fragments. The soil is not calcareous. Organic matter ranges from 1 to 3 percent to a depth of 20 cm. Rock fragments on the surface range from 0 to 10 percent gravel and 0 to 5 percent cobbles.
The A horizon dry color is 10YR 4/3, 4/2 or 3/2. Moist color is 10YR 3/3, 3/2 or 2/2. Texture is clay loam. Clay content ranges from 35 to 40 percent. Rock fragments range from 10 to 25 percent gravel. Reaction ranges from 6.1 to 7.3.
The Bw horizon dry color is 10YR 4/2, 3/3, 7.5YR 4/3 or 3/2. Moist color is 10YR 3/2, 2/2, 7.5YR 3/3 or 2.5/2. Texture is clay loam or clay. Clay content ranges from 35 to 45 percent. Rock fragments range from 15 to 40 percent gravel and 5 to 50 percent cobbles. Reaction ranges from 6.1 to 7.3.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Unistan soils are on hills. Slopes are 5 to 30 percent. These soils formed in residuum weathered from basalt. Elevation is 300 to 500 feet. Mean annual precipitation is 18 to 22 inches. The mean annual air temperature is 60 to 62 degrees F. Frost free season is 275 to 325 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Zeppelin and Mccoy soils. The Zeppelin soils are deep to weathered sandstone, the Mccoy soils have fine-loamy textural control sections and are moderately deep to weathered sandstone.
DRAINAGE AND PERMEABILITY: well drained; slow permeability.
USE AND VEGETATION: This soil is used for recreation and urban uses. Vegetation is the natural state is annual grasses with scattered oaks.
DISTRIBUTION AND EXTENT: The soils are not extensive with limited acreage and are mapped in Santa Clara County. Major Land Resource Area: 15 -- Central California Coast Range
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Santa Clara County, California 2009. Source of name coined from Stanford University.
REMARKS:
Particle Size Control Section for this pedon: 0 to 11 in, 0 to 28 cm
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 11 in. (0 to 28 cm.)
Cambic Horizon: 2 to 11 in. (6 to 28 cm)
The soil moisture control section is dry in all parts from about May 1 to November 1 (about 180 days).
ADDITIONAL DATA:
Pedon information for this type location: NASIS ID: 08ca085641159
Unistan soils were mapped as Los Trancos soils in the 1958 Santa Clara soil survey. The Los Trancos series was inactivated in 1984 due to limited acreage. No other series exists with any similarity for these soils.