LOCATION ALUMROCK CAEstablished Series
The Alumrock series consists of moderately deep, well drained soils that formed in residuum from sandstone. Alumrock soils are on hills. Slopes range from 9 to 50 percent. The mean annual precipitation is about 20 inches, and the mean annual temperature is about 60 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Pachic Argixerolls
TYPICAL PEDON: Alumrock fine sandy loam, on a north west facing 35 percent slope under a cover of scattered oaks and annual grasses at an elevation of 387 feet. When described the soil was dry throughout. (Colors are for dry soil unless otherwise noted).
Oi--0 to 1 inches, (0 to 2 cm); dark grayish brown (10YR 4/2) exterior slightly decomposed plant material, very dark brown (10YR 2/2) exterior moist; abrupt smooth boundary.
A--1 to 5 inches, (2 to 12 cm); brown (10YR 5/3) broken face fine sandy loam, dark brown (10YR 3/3) broken face moist; 14 percent clay; strong fine subangular blocky structure; soft, very friable, slightly sticky, nonplastic; many very fine roots; many very fine interstitial pores; 2 percent subangular strongly cemented 2 to 75 millimeter sandstone fragments; moderately acid, pH 6.0 by pH meter 1:1 water; clear smooth boundary. (12 to 30 centimeters thick)
ABt1--5 to 12 inches, (12 to 30 cm); brown (10YR 5/3) broken face fine sandy loam, dark brown (10YR 3/3) broken face moist; 19 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common very fine roots; common fine tubular and many very fine interstitial pores; 2 percent subangular strongly cemented 2 to 75 millimeter sandstone fragments; strongly acid, pH 5.4 by pH meter 1:1 water; abrupt smooth boundary.
ABt2--12 to 19 inches, (30 to 49 cm); brown (10YR 5/3) broken face sandy clay loam, dark brown (10YR 3/3) broken face moist; 22 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common very fine roots; common very fine tubular and many very fine interstitial pores; 50 percent clay films on all faces of peds; 1 percent subangular strongly cemented 2 to 75 millimeter sandstone fragments; very strongly acid, pH 4.5 by pH meter 1:1 water; clear smooth boundary.
Bt1--19 to 26 inches, (49 to 66 cm); brown (10YR 5/3) broken face sandy clay loam, dark brown (10YR 3/3) broken face moist; 23 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; few fine roots and common very fine roots; many fine tubular and many very fine interstitial pores; 80 percent clay films on all faces of peds; 1 percent subangular strongly cemented 2 to 75 millimeter sandstone fragments; very strongly acid, pH 4.5 by pH meter 1:1 water; abrupt smooth boundary.
Bt2--26 to 30 inches, (66 to 76 cm); yellowish brown (10YR 5/4) broken face sandy clay loam, dark yellowish brown (10YR 3/4) broken face moist; 25 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many fine tubular and many very fine interstitial pores; 80 percent clay films on all faces of peds; 1 percent subangular strongly cemented 2 to 75 millimeter sandstone fragments; very strongly acid, pH 4.9 by pH meter 1:1 water; abrupt smooth boundary. (Combined thickness of the ABt and Bt horizons is 40 to 64 centimeters thick)
Cr--30 to 31 inches, (76 to 78 cm); moderately cemented sandstone bedrock; hard, coarse-grained sandstone, unfractured.
TYPE LOCATION: Santa Clara County, California, Guadalupe Grove Park, San Jose, north side of main hill, up the hill from dirt road., in an unsectionalized area of Township 8S, Range 1E, 4121762 Northing, 599242 Easting, UTM Zone 10, NAD83 - U.S.G.S Quad: Los Gatos, California.
RANGE IN CHARACTERISTICS: Depth to slightly weathered sandstone is 50 to 100 cm. The mean annual soil temperature is 60 to 62 degrees F. The particle size control section averages 18 to 24 percent clay, and 1 to 35 percent rock fragments, mostly gravel. The soil is not calcareous. Organic matter ranges from 1 to 3 percent to a depth of 25 cm. Rock fragments on the surface range from 0 to 10 percent gravel.
The A horizon dry color is 10YR 5/3, 4/2 or 7.5 YR 4/3. Moist color is 10YR 3/3, 2/2 or 7.5YR 2.5/3. Texture is fine sandy loam, sandy loam or loam. Clay content ranges from 14 to 16 percent. Rock fragments range from 2 to 35 percent gravel. Reaction ranges from 5.6 to 7.
The ABt horizon dry color is 10YR 5/3. Moist color is 10YR 3/3. Texture is fine sandy loam, sandy clay loam or loam. Clay content ranges from 19 to 22 percent. Rock fragments range from 1 to 35 percent gravel. Reaction ranges from 4.5 to 7. Not all pedons have AB horizons.
The Bt horizon dry color is 10YR 5/4, 5/3 or 7.5 YR 4/3. Moist color is 10YR 3/4, 3/3 or 7.5YR 3/3. Texture is sandy clay loam or loam. Clay content ranges from 18 to 24 percent. Rock fragments range from 1 to 35 percent gravel. Reaction ranges from 4.5 to 7.
COMPETING SERIES: These are the Arujo, Botella, Chico, Elkhorn, Havala, Kawenga, Lockwood, Mccoy, Minlum, Rimtrail, Saltcanyon, Sapwi and Tongva soils. Arujo soils have a paralithic contact at 100 to 150cm. Botella, Chico, Elkhorn, Havala, Lockwood, Minlum, Rimtrail and Saltcanyon soils are very deep. Kawenga soils have a paralithic contact at 100 to 150cm. Mccoy soils have 25 to 35 percent clay in the textural control section. Sapwi soils have a lithic contact at 50 to 100cm. Tongva soils have 18 to 35 percent clay in the textural control section with textures of clay loam and loam, and they are developed from andesite and basalt.
GEOGRAPHIC SETTING: Alumrock soils are on hills. Slopes are 9 to 50 percent. These soils formed in residuum weathered from sandstone. Elevation is 300 to 800 feet. Mean annual precipitation is 20 to 22 inches. The mean annual temperature is 60 to 64 degrees F. Frost free season is 275 to 325 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Zeppelin soils. The Zeppelin soils are deep to a paralithic contact and fine textured.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability above the sandstone.
USE AND VEGETATION: This soil is used for recreation and urban uses. Vegetation is oaks and annual grasses in recreation areas and urban areas have lawn grasses and ornamental plants.
DISTRIBUTION AND EXTENT: The soils are inextensive 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 from Park on east side of San Jose.
REMARKS
Particle Size Control Section for this pedon: 11.8 to 30 in. (30 to 76 cm)
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 26 in. (0 to 66 cm)
Argillic Horizon: 30 to 76 in. (30 to 76 cm)
The soil moisture control section is dry in all parts from about May 1 to November 1 (about 180 days).
ADDITIONAL DATA -- USER SITE ID: 08ca085641199