LOCATION MINEHART                CA

Established Series
Rev: LJL/CAH/ET
11/2015

MINEHART SERIES

The Minehart series consists of very deep, well drained soils that formed in alluvium derived from volcanic and metamorphic rocks. Minehart soils are on fan remnants. Slope ranges from 2 to 8 percent. The mean annual precipitation is about 200 millimeters and the mean annual temperature is about 18 degrees C. The frost-free season is 180 to 240 days.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Ustic Paleargids

TYPICAL PEDON: Minehart gravelly fine sandy loam, on a 5 percent slope under desert rangeland at an elevation of 1,397 meters. When described the soil was dry throughout. (Colors are for dry soil unless otherwise noted). The soil surface is covered by approximately 50 percent gravel, 3 percent cobbles and 1 percent stones.

A--0 to 7 centimeters (0 to 3 inches); brown (10YR 5/3) gravelly fine sandy loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; few very fine roots; common very fine interstitial pores and few fine tubular; 5 percent fine gravel and 10 percent medium and coarse gravel and 1 percent cobbles; slightly alkaline (pH 7.8); abrupt wavy boundary. (7 to 8 centimeters thick)

Bt--7 to 20 centimeters (3 to 8 inches); yellowish brown (10YR 5/4) gravelly loam, dark yellowish brown (10YR 3/4) moist; moderate medium and coarse subangular blocky structure; moderately hard, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; common very fine and few fine tubular pores; 5 percent faint clay films on rock fragments; 15 percent fine gravel and 15 percent medium and coarse gravel and 3 percent cobbles; slightly alkaline (pH 7.8); clear wavy boundary.

Btk1--20 to 33 centimeters (8 to 13 inches); brown (7.5YR 5/4) loam, dark brown (7.5YR 3/4) moist; moderate medium subangular blocky structure; moderately hard, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; many very fine and few fine tubular pores; 20 percent faint clay films on all faces of peds, surfaces along pores, rock fragments, and between sand grains; 20 percent prominent, white (10YR 8/1), calcium carbonate coats on bottom surfaces of rock fragments; 5 percent fine and 10 percent medium and coarse gravel; slightly alkaline (pH 7.8); clear wavy boundary.

Btk2--33 to 52 centimeters (13 to 21 inches); brown (7.5YR 4/4) clay loam, brown (7.5YR 4/4) moist; moderate medium and coarse subangular blocky structure; hard, very friable, moderately sticky and moderately plastic; common very fine and few fine roots; common very fine and fine tubular pores; 40 percent distinct clay films on all faces of peds, surfaces along pores, and rock fragments; 20 percent prominent, white (10YR 8/1), calcium carbonate coats on bottom surfaces of rock fragments; 5 percent fine and 10 percent medium and coarse gravel; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (The combined thickness of the Bt and Btk horizons is 40 to 100 centimeters.)

2Btk3--52 to 96 centimeters (21 to 38 inches); brown (7.5YR 5/4) extremely gravelly coarse sandy loam, brown (7.5YR 4/4) moist; massive, very hard, very friable, slightly sticky and slightly plastic; few very fine roots; common very fine interstitial pores and few fine tubular; 20 percent distinct clay films on rock fragments and between sand grains; 20 percent prominent, white (10YR 8/1), calcium carbonate coats on bottom surfaces of rock fragments; 15 percent fine gravel and 45 percent medium and coarse gravel and 5 percent cobbles; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary.

2Btk4--96 to 152 centimeters (38 to 60 inches); light brown (7.5YR 6/4) extremely gravelly coarse sandy loam, brown (7.5YR 4/4) moist; massive, slightly hard, very friable, slightly sticky and nonplastic; few very fine roots; common very fine and few fine tubular pores; 5 percent faint, clay films on rock fragments; 20 percent prominent, white (10YR 8/1), calcium carbonate coats on bottom surfaces of rock fragments; 20 percent fine gravel and 40 percent medium and coarse gravel and 5 percent cobbles; strongly effervescent; moderately alkaline (pH 8.4). (The combined thickness of the 2Btk horizons is greater than 50 centimeters.)

TYPE LOCATION: San Bernardino County, California; about 18 kilometers south and 5 kilometers west of the Walking Box Ranch, 11 kilometers west of Searchlight, Nevada, on the west side of the Castle Mountains; approximately 4 kilometers north of Hart mine site; about 420 meters south and 670 meters east of the northwest corner of section 1, T. 14 N., R. 17 E.; USGS Hart Peak, CA-NV 7.5 minute topographic quadrangle; 35 degrees, 19 minutes, 38.1 seconds north latitude and 115 degrees, 6 minutes, 8.1 seconds west longitude; UTM 11S, 672491e 3910987n; (DATUM: NAD83).

RANGE IN CHARACTERISTICS:

Soil moisture - Usually dry, moist in some part from December to March and intermittently moist for 10 to 20 days during July to October following summer convection storms; aridic moisture regime bordering on ustic.

Soil temperature: 15 to 18 degrees C.

Depth to argillic horizon: 5 to 10 centimeters.

Clay content: Averages 18 to 27 percent.
Control section - Rock fragments: Averages 5 to 20 percent, mainly gravel.

A horizon
Value: 3 or 4 moist.
Chroma: 3 or 4 dry.
Rock fragments: 5 to 40 percent.

Bt or Btk horizons
Hue: 10YR or 7.5YR.
Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Texture of the fine earth fraction: Loam, clay loam, sandy clay loam, clay or sandy loam.
Clay content: Averages 18 to 27 percent, ranges from 12 to 45 percent.
Structure: Moderate or strong, medium through very coarse.
Consistence: Moderately hard through very hard, very friable or friable, slightly sticky or moderately sticky, slightly plastic or moderately plastic.
Rock fragments: Averages 5 to 20 percent, ranges from 5 to 35 percent.
Reaction: Slightly or moderately alkaline.

2Btk horizons
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Texture of the fine earth fraction: Coarse sandy loam or sandy loam.
Clay content: 8 to 18 percent.
Structure: Weak, medium or coarse, subangular blocky or massive.
Consistence: Moderately hard through very hard, very friable or friable, slightly sticky or moderately sticky, slightly plastic or moderately plastic.
Rock fragments: 35 to 70 percent.
Reaction: Slightly or moderately alkaline.

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

GEOGRAPHIC SETTING: Minehart soils are on fan remnants. Slope ranges from 2 to 8 percent. These soils formed in alluvium derived from volcanic and metamorphic rocks. Elevations are 1,300 to 1,450 meters. The climate is semiarid with cool, moist winters and warm, intermittently moist summers. The mean annual precipitation is 180 to 230 millimeters; mean annual air temperature is 17 to 19 degrees C., and the frost-free season is 180 to 240 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Hartpeak, Hoppswell and Ustidur soils. Hartpeak soils have bedrock at 50 to 75 centimeters and occur on back slopes of hills and mountains. Hoppswell soils have a loamy-skeletal control sections and are found on nearby fan remnants. Ustidur soils have a duripan, do not have an argillic horizon, and occur on ballenas.

DRAINAGE AND PERMEABILITY: Well drained; high runoff; very slow permeability.

USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. The present vegetation is mainly galleta, bush muhly, black grama, Coopers goldenbush and banana yucca.

DISTRIBUTION AND EXTENT: Mojave Desert of southeastern California; MLRA 30. These soils are not extensive.

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

SERIES ESTABLISHED: San Bernardino County, California; Crescent Peak Grazing Allotment, part of the Mojave National Preserve Soil Survey Area, California, 2007. The name is coined from Hart mine located in northern Lanfair Valley.

REMARKS: Diagnostic horizons and features recognized in the profile are:

1. Ochric epipedon - 0 to 7 centimeters (0 to 3 inches). (A horizon)
2. Argillic horizon - 7 to 52 centimeters (3 to 21 inches). (Bt, Btk1 and Btk2 horizons)
3. Particle-size control section - 7 to 52 centimeters (3 to 21 inches). (Bt, Btk1 and Btk2 horizons)
4. Note: There is a clay increase of 15 percent or more in the argillic horizon within 2.5 centimeters.

Responsibility for this series was transferred from Davis to Phoenix 11/2015. The last revision to the series was 5/2007. ET

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National Cooperative Soil Survey
U.S.A.