LOCATION COXPIN                  CA

Established Series
REV: PBF/CAH/ET
04/2015

COXPIN SERIES

The Coxpin series consists of shallow, somewhat excessively drained soils that formed in alluvium from igneous rocks. Coxpin soils are on fan remnants and fan aprons over fan remnants. Slopes range from 2 to 8 percent. The mean annual precipitation is about 100 millimeters (4 inches) and the mean annual air temperature is about 21.5 degrees C (71 degrees F).

TAXONOMIC CLASS: Sandy, mixed, hyperthermic, shallow Cambidic Haplodurids

TYPICAL PEDON: Coxpin loamy fine sand, on an east northeast-facing, convex, 3 percent slope under sparse desert shrubs at an elevation of 329 meters (1,079 feet). When described the soils were dry throughout. (Colors are for dry soil unless otherwise noted.) The surface is covered by approximately 15 percent fine gravel, 45 percent medium and coarse gravel and 5 percent cobbles.

A -- 0 to 3 centimeters (0 to 1 inch); light brown (7.5YR 6/4) loamy fine sand, yellowish brown (10YR 5/4) moist; weak medium platy structure parting to moderate fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; very few very fine roots; few very fine, fine, medium and coarse vesicular pores; 8 percent fine gravel and 2 percent medium and coarse gravel; violently effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (2 to 6 centimeters thick)

Bw -- 3 to 26 centimeters (1 to 10 inches); strong brown (7.5YR 5/6) gravelly sandy loam, brown (7.5YR 5/4) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; very few very fine roots; 10 percent fine gravel and 5 percent medium and coarse gravel; very slightly effervescent; moderately alkaline (pH 8.0); clear wavy boundary.

Bk -- 26 to 42 centimeters (10 to 16 inches); yellowish brown (10YR 5/6) gravelly loamy sand, light yellowish brown (10YR 6/4) moist; massive; slightly hard, very friable, nonsticky and nonplastic; 2 percent fine gravel; violently effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (Combined thickness of Bw and Bk horizons is 10 to 47 centimeters).

Bkq -- 42 to 56 centimeters (16 to 22 inches); very pale brown (10YR 8/2) weakly cemented sand, very pale brown (10YR 8/3) moist, duripan with 60 percent cementation; massive; hard, firm, brittle, nonsticky and nonplastic; violently effervescent; gradual wavy boundary. (11 to 67 centimeters thick)

Ck -- 56 to 150 centimeters (22 to 59 inches); very pale brown (10YR 7/3) sand, pale brown (10YR 6/3) moist; massive; loose, nonsticky and nonplastic; 5 percent fine gravel and 3 percent medium and coarse gravel; violently effervescent; strongly alkaline (pH 8.5).

TYPE LOCATION: Riverside County, California; approximately 16.7 kilometers north northwest of the junction of Highway 177 and MWD Aqueduct Road; 635 meters (2,083 feet) north and 228 meters (748 feet) east of the SW corner of section 16, T. 3 S., R. 15 E., San Bernardino Base and Meridian; 33 degrees, 54 minutes and 33.2 seconds north latitude, and 115 degrees, 25 minutes and 15.8 seconds west longitude; USGS Pinto Wells 7.5 minute topographic quadrangle; UTM 11S 0645974e 3753213n (DTM: NAD83).

RANGE IN CHARACTERISTICS:

Soil moisture control section: usually dry, moist in some parts for short
periods during winter and early spring and for 10 to 20 days cumulative
between July and September following summer convection storms. The soils have a typic-aridic soil moisture regime.

Soil temperature: 22 to 25 degrees C (72 to 77 F).
Surface rock fragments: 45 to 90 percent; with 15 to 45 percent fine gravel,
15 to 50 percent medium and coarse gravel, 0 to 15 percent cobbles, and 0
to 2 percent stones.

Control section -
Depth to the upper boundary of a duripan: 36 to 50 centimeters (14 to 20
inches).
Rock fragments: averages 2 to 30 percent gravel.
Clay content: 1 to 8 percent.
Organic matter: 0 to 0.25 percent.

Some pedons have a rock layer C horizon above the A horizon with 80 to 90 percent rock fragments, dominated by fine gravel. (1 to 3 centimeters thick)

A horizon
Hue: 7.5YR or 10YR.
Value: 5 to 7 dry, 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Texture of the fine earth: fine sand, loamy fine sand, fine sandy loam,
or sandy loam.
Clay content: 2 to 12 percent.
Rock fragments: 4 to 14 percent gravel.
Effervescence: slightly through violently effervescent.
Calcium carbonate equivalent: 0 to 5 percent.
Reaction: slightly through strongly alkaline.
Other features: some horizons are characterized by vesicular pores.

Bk or Bw horizons
Hue: 7.5YR or 10YR.
Value: 5 to 8 dry, 4 to 7 moist.
Chroma: 2 to 6 dry, 3 to 6 moist.
Texture of the fine earth: sand, fine sand, loamy sand, loamy fine sand,
fine sandy loam or sandy loam.
Clay content: 2 to 12 percent.
Rock fragments: 1 to 35 percent; with 1 to 15 percent gravel in the upper
part and 10 to 35 percent in the lower part.
Effervescence: very slightly through violently effervescent.
Calcium carbonate equivalent: 0 to 15 percent.
Salinity: 0 to 4 dS/m.
Reaction: moderately through very strongly alkaline.

Bkq(m) horizon
Hue: 7.5YR, 10YR, or 2.5Y.
Value: 6 to 8 dry, 5 to 7 moist.
Chroma: 3 or 4 dry, 3 to 6 moist.
Texture of the fine earth: sand or loamy sand.
Clay content: 1 to 6 percent.
Rock fragments: 1 to 30 percent gravel.
Effervescence: strongly or violently effervescent.
Calcium carbonate equivalent: 1 to 15 percent.
Salinity: 0 to 4 dS/m.
Reaction: moderately through very strongly alkaline.
Cementation: weak to strong, with 60 to 90 percent continuity.

Ck or Ckq horizon
Hue: 7.5YR, 10YR, or 2.5Y.
Value: 6 to 8 dry, 5 or 6 moist.
Chroma: 3 or 4, dry or moist.
Texture of the fine earth: sand, or fine sandy loam.
Clay content: 1 to 6 percent.
Rock fragments: 1 to 35 percent; with 1 to 35 percent gravel and 0 to 5
percent cobbles.
Effervescence: slightly through violently effervescent.
Calcium carbonate equivalent: 0 to 5 percent.
Salinity: 0 to 4 dS/m.
Reaction: moderately through very strongly alkaline.

COMPETING SERIES: There are no competing series at this time.

GEOGRAPHIC SETTING: Coxpin soils are on fan remnants and fan aprons over fan remnants. Slopes range from 2 to 8 percent. These soils formed in alluvium from igneous rocks. Elevations range from 290 to 780 meters (951 to 2,560 feet). The climate is arid, with hot, dry summers and warm, moist winters. The mean annual precipitation is 75 to 125 millimeters (3 to 5 inches) and the mean annual air temperature is 20 to 26 degrees C (68 to 79 degrees F). The frost-free season is 300 to 340 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aquapeak, Buzzardsprings, Dalelake and Perurose soils. Aquapeak and Buzzardsprings soils are on similar landscape positions, Dalelake soils are on adjacent sandsheets with Perurose soils on adjacent, steeper and well developed fan remnants. Aquapeak soils are shallow and have an argillic horizon above a duripan. Buzzardsprings soils have a calcic horizon and do not have a duripan. Dalelake soils are very deep, are formed in eolian materials and have no diagnostic horizons. Perurose soils are more than 50 centimeters deep to a duripan.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well-drained; medium runoff; high saturated hydraulic conductivity above and below the duripan and moderately low saturated hydraulic conductivity within the duripan.

USE AND VEGETATION: Coxpin soils are used for recreation and wildlife habitat. The present vegetation is mainly creosote bush.

DISTRIBUTION AND EXTENT: Southern Mojave Desert of southeastern California. MLRA 30. These soils are of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: PHOENIX, ARIZONA

SERIES ESTABLISHED: Riverside County, California, Joshua Tree National Park Soil Survey, 2012. The name is coined.

REMARKS: Diagnostic horizons and features in this pedon include:

Ochric epipedon - from a depth of 0 to 3 centimeters (A horizon).
Duripan - from a depth of 42 to 56 centimeters (Bkq horizon).
Particle-size control section - from a depth of 25 to 42 centimeters (part of
the Bw and the Bkq horizon).

ADDITIONAL DATA: NASIS Pedon User ID: 12480134-H.

Responsibility for this series was transferred from Davis to Phoenix 4/2015. The last revision to the series was 4/2012. ET

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National Cooperative Soil Survey
U.S.A.