LOCATION HILLBRICK CAEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, calcareous, thermic Lithic Xerorthents
TYPICAL PEDON: Hillbrick sandy loam on a south facing convex slope of 50 percent under annual grasses and forbs (wild oats, red brome, redstem filaree) at 1,900 feet elevation. (Colors are for dry soil unless otherwise stated. When described (3/24/77) the soil was nearly dry throughout the profile.)
A1--0 to 2 inches; pale brown (10YR 6/3) sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; common very fine roots; many very fine interstitial and common very fine tubular pores; 5 percent shale fragments by volume, 2 mm to 10 mm diameter; violently effervescent, disseminated lime; moderately alkaline (pH 8.0); clear wavy boundary. (1 to 2 inches thick)
A2--2 to 15 inches; pale brown (10YR 6/3) channery sandy loam, brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine interstitial and few very fine tubular pores; 15 percent shale fragments, 2 mm to 10 mm in diameter; violently effervescent, disseminated lime; moderately alkaline (pH 8.0); clear irregular boundary. (9 to 18 inches thick)
R--15 inches; light brownish gray (10YR 6/2) moist; fractured calcareous shale. Fractures are 1 to 5 cm apart and have no rotational displacement.
TYPE LOCATION: Kern County, California, in the Orchard Peak area, about 1/3 miles north of Hwy. 41 and 1/4 mile east of the county line; about 200 feet south of dirt road in the NE1/4 NW1/4 SW1/4 of sec. 6, T.25S., R.17E., MDB&M.
RANGE IN CHARACTERISTICS: Depth to the lithic contact is 10 to 20 inches. The soil from a depth of 8 inches to the lithic contact is dry in all parts from about April 15 to November 15 and is moist in some parts the rest of they year. The mean annual soil temperature is 60 degrees F. and is never below 47 degrees F. at any time. Clay is 8 to 18 percent. Hillbrick soils have a xeric bordering on aridic moisture regime.
The A horizon has dry color of 10YR 5/3, 5/4, 6/2, 6/3, 7/3, 6/4 or 7/2 and moist color of 10YR 4/2, 4/4, 4/3 or 5/3. It is sandy loam, loam, or channery sandy loam. Reaction is neutral to moderately alkaline. Shale or gravel content ranges from 0 to 30 percent. Rock fragments are 2 mm to 2 cm in diameter. It is slightly to violently efferevescent. Some pedons contain up to 5 percent angular cobbles. Some pedons have a C horizon.
COMPETING SERIES: This is the Wisflat soil and the Calleguas, Daulton, Exchequer, Gaviota, Kilmer, and Mendi series in other families. Wisflat soils have a paralithic contact and are dry throughout for 120 days. Calleguas soils are loamy-skeletal. Daulton, Exchequer, and Gaviota soils are noneffervescent. Kilmer and Mendi soils are deeper than 20 inches.
GEOGRAPHIC SETTING: Hillbrick soils are on foothills and mountains and have slopes of 9 to 75 percent. The soils formed in material weathered from fractured calcareous shale or sandstone. Elevation ranges from 900 to 3,500 feet. The climate is semi-arid with hot dry summers and cool somewhat moist winters. Mean annual precipitation is 8 to 10 inches. Mean January temperature is 45 degrees F.; mean July temperature is 81 degrees F.; mean annual temperature varies from 58 degrees to 62 degrees F. Frost-free season is 200 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aido, Ayar, Bluestone, Gaviota, and Kilmer soils. Aido and Ayar soils are deeper than 20 inches and are fine. Bluestone soils are nonacid and are fine. Gaviota soils are nonacid. Kilmer soils are fine-loamy and deeper than 20 inches.
DRAINAGE AND PERMEABILITY: Well drained; low to medium runoff; moderately rapid permeability.
USE AND VEGETATION: Used mostly for range. Vegetation is mainly annual grasses and forbs but includes California juniper, rabbitbrush, and black sage in some areas.
DISTRIBUTION AND EXTENT: Coastal Ranges of California, MLRA 15. The soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Kern County, Northwestern Part, California, 1982.