LOCATION ROBBERSFIRE             NV

Established Series
Rev: LJL/ET/TM
12/2015

ROBBERSFIRE SERIES

The Robbersfire series consists of deep, well drained soils that formed in colluvium from limestone and dolomite. Robbersfire soils are on back slopes of mountains. Slope ranges from 30 to 75 percent. The mean annual precipitation is about 20 inches and the mean annual air temperature is about 43 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, carbonatic, frigid Calcic Haplustepts

TYPICAL PEDON: Robbersfire very gravelly silt loam, forest and wildlife habitat. (Colors are for dry soil unless otherwise noted.) The soil surface is covered by approximately 45 percent pebbles, 5 percent cobbles and 1 percent stones. Additionally, 30 percent of the soil surface is covered by duff.

Oi--0 to 1 inches; very dark brown (10YR 2/2) slightly decomposed plant material, very dark brown (10YR 2/2) moist; abrupt wavy boundary. (0.5 to 2 inches thick)

A--1 to 2 inches; brown (10YR 4/3) very gravelly silt loam, very dark brown (10YR 2/2) moist; moderate very thick platy structure; soft, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine and common fine tubular pores; 40 percent pebbles, 3 percent cobbles and 1 percent stones; 4 percent calcium carbonate equivalent in the fine earth fraction; slightly alkaline (pH 7.6); abrupt smooth boundary. (1 to 4 inches thick)

Bk1--2 to 10 inches; dark yellowish brown (10YR 4/4) very gravelly silt loam, dark yellowish brown (10YR 3/4) moist; strong coarse subangular blocky structure; moderately hard, very friable, slightly sticky and slightly plastic; common very fine and coarse to very coarse roots; many very fine and common fine tubular pores; few prominent calcium carbonate coats white (10YR 8/1) on bottom of rock fragments; 3 percent fine soft masses of charcoal; 35 percent pebbles and 2 percent cobbles; 4percent calcium carbonate equivalent in the fine earth fraction; slightly alkaline (pH 7.8);clear wavy boundary. (6 to 10 inches thick)

Bk2--10 to 27 inches; dark grayish brown (10YR 4/2) very gravelly loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky; soft, very friable, slightly sticky and slightly plastic; common very fine, medium and coarse and many very coarse roots; few very fine and fine tubular pores; common fine calcium carbonate concentrations light gray (10YR 7/1) on bottom of rock fragments; few prominent calcium carbonate coats white (10YR 8/1) on bottom of rock fragments; 50 percent pebbles and 2 percent cobbles; violently effervescent (60 percent calcium carbonate equivalent in the fine earth fraction); moderately alkaline (pH 8.0);clear wavy boundary.

Bk3--27 to 41 inches; dark grayish brown (10YR 4/2) extremely gravelly fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky; soft, very friable, slightly sticky and slightly plastic; many very fine and fine and common medium, coarse and very coarse roots; many very fine tubular pores; common fine calcium carbonate concentrations white (10YR 8/1) on bottom of rock fragments; few prominent calcium carbonate coats white (10YR 8/1) on bottom of rock fragments; 60 percent pebbles and 10 percent cobbles; violently effervescent (90 percent calcium carbonate equivalent in the fine earth fraction); moderately alkaline (pH 8.1); very abrupt wavy boundary. (Combined thickness of the Bk2 and Bk3 horizons is 30 to 47 inches.)

R--41 inches; hard limestone

TYPE LOCATION: Clark County, Nevada; about 8 miles north and 27 miles west of Las Vegas, Nevada; approximately 3 miles east and 1.5 miles south of Angel Peak; 2,710 feet south and 1,790 feet west of the northeast corner of section 18, T. 19 S., R. 57 E.; USGS Angel Peak, NV 7.5 minute topographic quadrangle; 36 degrees, 17 minutes, 55.8 seconds north latitude and 115 degrees, 37 minutes, 27.6 seconds west longitude; UTM zone 11, 0623519e, 4017973n, NAD83.

RANGE IN CHARACTERISTICS:

Soil moisture usually moist in late winter and spring, and periodically moist in the upper part following summer convection storms; ustic soil moisture regime

Soil temperature: 44 to 47 degrees F.

Depth to the base of noneffervescent soil material: 7 to 14 inches (from the top of the mineral soil surface).

Depth to calcic horizon: 7 to 14 inches (from the top of the mineral soil surface).

Depth to lithic contact: 40 to 60 inches.

Control section - Rock fragments: 35 to 75 percent.
Clay content: Averages 5 to 15 percent.

Oi horizon Organic matter: 30 to 50 percent.

A horizon - Value: 2 to 5 dry, 2 or 3 moist.
Chroma: 3 or 4 dry, 2 or 3 moist.
Structure: Platy or subangular blocky.
Consistence: Soft to moderately hard, nonsticky or slightly sticky, and nonplastic or slightly plastic.
Rock fragments: 35 to 60 percent.
Organic matter: 4 to 8 percent.

Bk1 or Bw horizons - Value: 4 to 6 dry, 2 to 4 moist.
Chroma: 1 to 4.
Texture: Silt loam or loam.
Structure: Medium or strong, fine to coarse.
Consistence: Soft to moderately hard, very friable or friable, nonsticky or slightly sticky, and nonplastic or slightly plastic.
Clay content: 10 to 27 percent.
Rock fragments: 35 to 70 percent.
Organic matter: 2 to 5 percent.
Reaction: Slightly alkaline or moderately alkaline.
Calcium carbonate equivalent in the fine earth fraction: 0 to 10 percent.

Bk2 and Bk3 horizons - Value: 4 to 6 dry, 2 to 4 moist.
Chroma: 1 to 4.
Texture: Loam or fine sandy loam.
Structure: Medium or strong, fine to coarse.
Consistence: Soft to moderately hard, very friable or friable, nonsticky or slightly sticky, and nonplastic or slightly plastic.
Clay content: 4 to 15 percent.
Rock fragments: 35 to 75 percent, mainly gravels or cobbles with 0 to 10 percent stones.
Organic matter: 0.25 to 5 percent.
Effervescence: Strongly effervescent or violently effervescent.
Calcium carbonate equivalent in the fine earth fraction: 50 to 90 percent.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Robbersfire soils are on back slopes of mountains. These soils formed in colluvium from limestone and dolomite. Slope ranges from 30 to 75 percent. Elevations are 7,500 to 9,700 feet. The climate is sub-humid continental, cool, with moist winters and common late summer convection storms. The mean annual precipitation is 18 to 24 inches; mean annual air temperature is 40 to 45 degrees F., and the frost-free season is 50 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Maryjane, Mountmummy, Ladyofsnow and Thesisters soils. Maryjane soils are located at lower elevations and are dominated by ponderosa pine. Mountmummy and Ladyofsnow soils are at higher elevations and are dominated by Great Basin bristlecone pine. Thesisters soils are shallow and less productive ponderosa pine sites.

DRAINAGE AND PERMEABILITY: Well drained; high runoff; moderate permeability.

USE AND VEGETATION: These soils are used for forest and wildlife habitat. The present vegetation is mainly white fir, Great Basin bristlecone pine, and currant.

DISTRIBUTION AND EXTENT: Mojave Desert of southern Nevada; MLRA 30. These soils are moderately extensive.

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

SERIES ESTABLISHED: Clark County Area, Nevada, 2006. Proposed in Clark County, Nevada; Clark County Soil Survey, 2005. The name is coined from Robbers Fire (2004) located to the southeast, in the Spring Mountains.

REMARKS: Soil was reclassified from Loamy-skeletal, mixed, superactive, frigid Typic Haplustepts to Loamy-skeletal, carbonatic, frigid Typic Haplustepts during progress field review, August 30, 2004. Reclassified to Loamy-skeletal, carbonatic, frigid Calcic Haplustepts during Final Correlation, March 14, 2006.

Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 7 inches (Oi and A horizons and part of the Bk1 horizon).
Cambic horizon - 2 to 10 inches (Bk1 horizon).
Calcic horizon - 10 to 41 inches (Bk2 and Bk3 horizons).
Lithic contact at 41 inches (R layer).
Particle-size control section - 11 to 41 inches (part of the Bk2 and Bk3 horizons).

ADDITIONAL DATA: Sampled on October 6, 2004, by NRCS Nevada staff, samples sent to NSSL, Lincoln, NE. Pedon ID is S04NV-003-007.

Responsibility for this series was transferred from Davis to Phoenix 12/2015. The last revision to the series was 8/2006. ET

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National Cooperative Soil Survey
U.S.A.