LOCATION ROCKHOUND               CA

Established Series
Rev: PBF/CAH/ET
12/2015

ROCKHOUND SERIES

The Rockhound series consists of very deep, well drained soils that formed in alluvium from granitoid and/or gneissic rocks. Rockhound soils are on fan remnants. Slopes range from 2 to 15 percent. The mean annual precipitation is about 75 millimeters (3 inches) and the mean annual air temperature is about 24.5 degrees C (76 degrees F).

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, hyperthermic Typic Haplargids

TYPICAL PEDON: Rockhound gravel, on a south-southeast-facing, linear, 2 percent slope under sparse desert shrubs at an elevation of 421 meters (1,381 feet). (Colors are for dry soil unless otherwise noted.)

C -- 0 to 4 centimeters (0 to 1.5 inches); gravel; 10 percent fine gravel, 70 percent medium and coarse gravel, 14 percent cobbles and 1 percent stones; abrupt wavy boundary. (2 to 10 centimeters thick)

A -- 4 to 9 centimeters (1.5 to 3.5 inches); light brown (7.5YR 6/4) very gravelly loam, brown (7.5YR 4/4) moist; moderate thick platy parting to weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; few very fine, fine, medium and coarse vesicular pores; 15 percent fine gravel, 15 percent medium and coarse gravel and 5 percent cobbles; violently effervescent; moderately alkaline (pH 8.3); clear wavy boundary. (1 to 6 centimeters thick)

Bk -- 9 to 19 centimeters (3.5 to 7.5 inches); light brown (7.5YR 6/4) very gravelly loam, strong brown (7.5YR 4/6) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; 1 percent prominent, very pale brown (10YR 8/2) carbonate coats on bottom of rock fragments; 20 percent fine gravel, 30 percent medium and coarse gravel and 1 percent cobbles; violently effervescent; moderately alkaline (pH 8.1); abrupt wavy boundary. (0 to 10 centimeters thick)

Btq1 -- 19 to 43 centimeters (7.5 to 17 inches); yellowish red (5YR 4/6) gravelly loam, yellowish red (5YR 4/6) moist; moderate fine and medium subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; few very fine and medium roots; 25 percent distinct, reddish brown (5YR 4/4) clay films on ped faces; 15 percent, prominent, very pale brown (10YR 7/3) silica coats on bottom of rock fragments; 15 percent fine gravel,10 percent medium and coarse gravel and 1 percent cobbles; slightly alkaline (pH 7.6); gradual wavy boundary.

Btq2 -- 43 to 87 centimeters (17 to 34 inches); yellowish red (5YR 4/6) extremely gravelly sandy clay loam, yellowish red (5YR 4/6) moist; weak medium subangular blocky structure; moderately hard, friable, moderately sticky, slightly plastic; few very fine and medium roots; 5 percent distinct, reddish brown (5YR 4/4) clay films on ped faces; 15 percent, prominent, very pale brown (10YR 7/3) silica coats on bottom of rock fragments; 30 percent fine gravel, 30 percent medium and coarse gravel and 3 percent cobbles; slightly alkaline (pH 7.8); gradual wavy boundary. (Combined thickness of the Bt horizons is 20 to 70 centimeters)

Bkq1 -- 87 to 114 centimeters (34 to 45 inches); strong brown (7.5YR 4/6) very gravelly sandy loam, brown (7.5YR 5/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; 10 percent, prominent, very pale brown (10YR 7/3) silica coats on bottom of rock fragments; 25 percent fine gravel and 25 percent medium and coarse gravel; slightly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary.

Bkq2 -- 114 to 152 centimeters (45 to 60 inches); yellowish brown (10YR 5/6) very gravelly sandy loam, yellowish brown (10YR 5/4) moist; massive; soft, very friable, slightly sticky and slightly plastic; 10 percent, prominent, very pale brown (10YR 7/3) silica coats on bottom of rock fragments; 25 percent fine gravel and 20 percent medium and coarse gravel; strongly effervescent; moderately alkaline (pH 8.1).

TYPE LOCATION: Riverside County, California; approximately 10.5 kilometers (6.5 miles) north northwest of Desert Center, California, and 2.7 kilometers (1.6 miles) west southwest of the junction of Eagle Mountain and MWD Agueduct Roads; 670 meters (2,198 feet) south and 265 meters (869 feet) west of the SE corner of sec. 35, T. 4 S., R. 14 E., San Bernardino Base and Meridian; 33 degrees, 46 minutes and 40.7 seconds north latitude and 115 degrees, 28 minutes and 50.3 seconds west longitude; USGS Victory Pass 7.5 minute topographic quadrangle; UTM 11S 0640681e 3738577n (DTM: NAD83).

RANGE IN CHARACTERISTICS:

Soil moisture control section: usually dry throughout, rarely moist in some
parts during winter, summer and early fall. The soils have a typic-aridic
soil moisture regime.

Soil temperature: 25 to 28 degrees C (77 to 82 F).
Surface rock fragments: 90 to 100 percent; with 10 to 20 percent fine gravel,
60 to 78 percent medium and coarse gravel, 5 to 20 percent cobbles and 1
to 3 percent stones.

Control section -
Rock fragments: averages 40 to 60 percent; gravel, cobbles and stones.
Clay content: ranges from 18 to 25 percent.
Organic matter: 0 to 0.25 percent.
Depth to the top of an argillic horizon: 6 to 20 centimeters (2.5 to 8
inches).

C horizon
90 to 100 percent rock fragments; 60 to 80 percent gravel, 10 to 17 percent cobbles and 1 to 3 percent stones.

A horizon
Hue: 7.5YR or 10YR.
Value: 5 or 6 dry, and 3 or 4, moist.
Chroma: 3 or 4 dry, and 3 to 6, moist.
Texture of the fine earth: fine sandy loam, silt loam or loam.
Clay content: 8 to 16 percent.
Rock fragments: 15 to 75 percent; with 10 to 60 percent gravel, 0 to 5 percent cobbles and 0 to 2 percent stones.
Effervescence: slightly to violently effervescent.
Calcium carbonate equivalent: 0 to 5 percent.
Reaction: slightly or moderately alkaline.
Other features: some pedons are characterized by vesicular pores in this horizon.

Bk(q) horizons
Hue: 7.5YR or 10YR.
Value: 4 to 6 dry, and 4 or 5, moist.
Chroma: 4 or 6, dry or moist.
Texture of the fine earth: sandy loam or loam.
Clay content: 15 to 20 percent.
Rock fragments: 45 to 69 percent; with 45 to 55 percent gravel, 0 to 12 percent cobbles and 0 to 2 percent stones.
Effervescence: slightly to violently effervescent.
Calcium carbonate equivalent: 0 to 10 percent.
Reaction: slightly or moderately alkaline.
Visible secondary carbonates: 0 to 3 percent as coats on rock fragments.
Silica: 0 to 5 percent silica coats on rock fragments.

Bt, Btq, Btk and Btkq horizons
Hue: 5YR or 7.5YR.
Value: 4 or 5, dry.
Chroma: 4 or 6, dry or moist.
Texture of the fine earth: loam or sandy clay loam.
Clay content: 18 to 26 percent.
Rock fragments: 25 to 65 percent; with 25 to 60 percent gravel, 0 to 15 percent cobbles and 0 to 3 percent stones.
Effervescence: slightly to violently effervescent.
Calcium carbonate equivalent: 0 to 5 percent.
Reaction: slightly or moderately alkaline.
Visible secondary carbonates: 0 to 10 percent as coats on rock fragments.
Silica: 0 to 15 percent silica coats on rock fragments.

Bkq or Ckq horizons
Value: 4 to 6, dry and 3 to 5, moist.
Chroma: 3 or 4, dry or moist.
Texture of the fine earth: sand or loamy sand.
Clay content: 2 to 20 percent.
Rock fragments: 35 to 69 percent; with 35 to 55 percent gravel, 0 to 5 percent cobbles and 0 to 2 percent stones.
Effervescence: noneffervescent to strongly effervescent.
Calcium carbonate equivalent: 0 to 5 percent.
Reaction: slightly or moderately alkaline.
Visible secondary carbonate: 0 to 3 percent as coats on rock fragments.
Silica: 0 to 5 percent films on rock fragments.

COMPETING SERIES: These are the Clegorpass (CA) and Oldale (CA) series. Both of these soils have a soil moisture control section that is moist in some part for 10 to 20 days, cumulative, between July and September and mean annual soil temperatures less than 25 degrees C, typical for soils in MLRA 30. In addition, Clegorpass soils have gypsum present within the particle-size control section.

GEOGRAPHIC SETTING: Rockhound soils are on fan remnants. Slopes range from 2 to 15 percent. These soils formed in alluvium from granitoid and/or gneissic rocks. Elevations range from 320 to 615 meters (1,050 to 2,015 feet). The climate is arid, with hot, dry summers and warm, moist winters. The mean annual precipitation is 50 to 100 millimeters (2 to 4 inches) and the mean annual air temperature is 23 to 26 degrees C (73.5 to 79 degrees F). The frost-free season is 360 to 365 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Deprave, Kenalduma, Rizzo and Roostertail soils. Deprave, Kenalduma and Roostertail soils are on similar landscape positions and have a duripan below an argillic horizon. Deprave, Kenalduma and Roostertail soils have a duripan with an upper boundary between 50 and 100 centimeters, 18 and 50 centimeters and 100 to 150 centimeters from the soil surface, respectively. Rizzo soils are in adjacent washes, inset fans and on some fan aprons and have sandy-skeletal particle-size control sections and no diagnostic horizons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; very low or medium runoff; high saturated hydraulic conductivity above and below the argillic horizon and moderately high saturated hydraulic conductivity within the argillic horizon.

USE AND VEGETATION: Rockhound soils are used for recreation and wildlife habitat. The present vegetation is mainly very sparse creosote bush, burrobush, brittlebush and ironwood.

DISTRIBUTION AND EXTENT: Colorado Desert of southeastern California. MLRA 31. These soils are of small extent.

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

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

REMARKS: Diagnostic horizons and features in this pedon include:

C horizon - from a depth of 0 to 4 centimeters.
Ochric epipedon - from a depth of 4 to 9 centimeters (A horizon).
Argillic horizon - from a depth of 19 to 87 centimeters (Btq horizons).
Particle-size control section - from a depth of 19 to 69 centimeters (Btq1
horizon and part of the Btq2 horizon).

ADDITIONAL DATA: NASIS Pedon User ID: VIPA03.

Responsibility for this series was transferred from Davis to Phoenix 12/2015. The last revision to the series was 5/2012. ET

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National Cooperative Soil Survey
U.S.A.