LOCATION KNUCKLE CAEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, thermic Lithic Xerorthents
TYPICAL PEDON: Knuckle loamy sand on a southeast facing hill with 66 percent slope under a cover of chamise at an elevation of 2,300 feet (699 meters). When described on 10/25/2005 the soil was dry throughout. Colors are for dry soils unless otherwise noted.
A--0 to 2 inches (0 to 4 centimeters); grayish brown (10YR 5/2), loamy sand, very dark grayish brown (10YR 3/2), moist; massive; soft, friable, nonsticky and nonplastic; many very fine, and common fine roots; many very fine irregular pores; 10 percent gravel; strongly acid (pH 5.1); abrupt smooth boundary. (2 to 7 inches, 4 to 18 centimeters thick)
Bw1--2 to 8 inches (4 to 20 centimeters); light yellowish brown (10YR 6/4), very gravelly loamy sand, dark yellowish brown (10YR 3/4), moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, common fine and medium roots; many very fine irregular pores; 35 percent gravel; neutral (pH 6.9); clear wavy boundary.
C--8 to 12 inches (20 to 30 centimeters); light yellowish brown (10YR 6/4), extremely stony loamy sand, dark yellowish brown (10YR 4/4), moist; single grain; loose, loose, nonsticky and nonplastic; common very fine and fine, and many medium roots; many very fine irregular pores; 15 percent gravel, 25 percent cobbles, 45 percent stones; neutral (pH 6.9); gradual irregular boundary. (Combined thickness of the Bw horizon is 6 to 11 inches, 14 to 29 centimeters)
R--12 to 23 inches (30 to 58 centimeters); indurated rhyolite bedrock.
TYPE LOCATION: San Benito County, California; 6,400 feet (1,940 meters) south along the Chalone Peak Trail from Bear Creek Reservoir and 50 feet (15 meters) southeast of the trail; 230 feet north and 770 feet east of the southwest corner of section 11, T 17S, R 7E; USGS North Chalone Peak, California topographic quadrangle; 36 degrees 27 minutes 30.40 seconds north latitude and 121 degrees 11 minutes 11.10 seconds west longitude; UTM 662539 meters E, 4036450 meters N, zone 10.
RANGE IN CHARACTERISTICS:
Depth to bedrock: 6 to 20 inches (16 to 50 centimeters).
Mean annual soil temperature: 60 to 63 degrees F (16 to 17 degrees C).
Soil moisture control section: dry in all parts from about May 15 to November 15 (180 days), and moist in all parts from about January 15 to April 15 (90 days).
Particle size control section: 2 to 15 percent clay, 35 to 60 percent rock fragments from rhyolite.
A horizon(s):
Hue: 10YR
Value: 5, 6 dry; 3 moist
Chroma: 2, 3 dry or moist
Texture of the fine earth fraction: Sandy loam, loamy sand
Clay content: 2 to 10 percent
Rock fragments: 10 to 40 percent gravel
Reaction: strongly acid to slightly acid
Bw horizon(s):
Hue: 10YR, 7.5YR
Value: 6, 7 dry; 3, 4 moist
Chroma: 2, 3, 4 dry or moist
Texture of the fine earth fraction: Loamy sand
Clay content: 2 to 15 percent
Rock fragments: 35 to 85 percent mostly gravel, cobbles and stones
Reaction: moderately acid to neutral
COMPETING SERIES: These are the Burgundy, Hideaway, Ranchoseco and Reliz soils. These four soils are all in the loamy-skeletal family. Burgundy soils are 4 to 10 inches (9 to 25 centimeters) deep to a lithic contact. Hideaway soils lack a Bw horizon. Ranchoseco soils contain 12 to 25 percent clay. Reliz soils have channers for rock fragments.
GEOGRAPHIC SETTING: The Knuckle soils are on shoulders and backslopes of hills. Slopes range from 35 to 70 percent. These soils formed in rhyolite. Elevation is 980 to 2,500 feet (300 to 760 meters). The climate is characterized by hot, dry summers and cool, moist winters. The mean annual precipitation is 17 to 19 inches (432 to 482 millimeters) and the mean annual air temperature is 59 to 63 degrees F (15 to 17 degrees C). The frost free season is 190 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Burgundy, Chalone, and Firstsister soils. The Burgundy soils are very shallow and in the loamy-skeletal family on shoulder slopes of hills under sparse chamise chaparral. Chalone soils are in the loamy-skeletal family, have a cambic horizon, and are moderately deep to lithic contact on hills under mixed chaparral. Firstsister soils are very deep with a mollic epipedon on toeslopes under hollyleaf cherry or live oak woodland.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained, rapid permeability, medium or high runoff. They do not flood or pond.
USE AND VEGETATION: This soil is used for watershed, wildlife habitat and recreation. Vegetation is sparse chamise chaparral.
DISTRIBUTION AND EXTENT: San Benito County, California in MLRA 15 -- Central California Coast Range. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: San Benito County, California. Source of name from Knuckle Ridge. This series was established based on limited acreage observed within the National Park Service Pinnacles National Monument boundary.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric Epipedon: the zone from 0 to 2 inches (0 to 4 centimeters) (A horizon)
Lithic Contact: 12 to 23 inches (30 to 58 centimeters) or more (R horizon)