LOCATION DEVILSTHUMB             NV

Established Series
LJL/TM/ET
04/2015

DEVILSTHUMB SERIES

The Devilsthumb series consists of moderately deep, well drained soils that formed in colluvium from limestone and sandstone. Devilsthumb soils are on backslopes 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 42 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Aridic Calciustepts

TYPICAL PEDON: Devilsthumb very gravelly loam, forest and wildlife habitat. (Colors are for dry soil unless otherwise noted.) The soil surface is covered by approximately 55 percent pebbles, 7 percent cobbles and 1 percent stones.

A--0 to 1 inch; brown (10YR 5/3) very gravelly loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine, common fine tubular pores; 40 percent pebbles and 5 percent cobbles; very slightly effervescent; neutral (pH 7.2); abrupt wavy boundary. (1 to 3 inches thick)

Bk1--1 to 7 inches; brown (10YR 5/3) very gravelly loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine, common fine through coarse roots; many very fine, common fine tubular pores; 5 percent, patchy, faint, light gray (10YR 7/2), calcium carbonate coats on bottom surfaces of rock fragments; 1 percent, patchy, prominent, reddish yellow (5YR 6/8) iron on surfaces of rock fragments; 40 percent pebbles and 3 percent cobbles; slightly effervescent; slightly alkaline (pH 7.4); clear wavy boundary. (6 to 10 inches thick)

Bk2--7 to 11 inches; brown (10YR 4/3) very gravelly loam, dark brown (10YR 3/3) moist; moderate medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine, common fine through very coarse roots; many very fine, common fine tubular pores; 60 percent, discontinuous, prominent, white (10YR 8/1) calcium carbonate coats on bottom surfaces of rock fragments; 10 percent, fine, prominent, very pale brown (10YR 8/2) calcium carbonate pendants on the bottom of rock fragments; 2 percent, patchy, prominent, reddish yellow (5YR 6/8) iron on surfaces of rock fragments; 40 percent pebbles and 3 percent cobbles; strongly effervescent (8 percent calcium carbonate equivalent in the fine earth fraction); slightly alkaline (pH 7.6); clear wavy boundary. (3 to 10 inches thick)

Bk3--11 to 26 inches; dark grayish brown (10YR 4/2) very gravelly loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine through very coarse roots; common very fine and few fine tubular pores; 70 percent, fine, prominent, white (10YR 8/1) calcium carbonate pendants on the bottom of rock fragments; 10 percent, patchy, prominent, reddish yellow (5YR 6/8) iron on surfaces of rock fragments; 40 percent pebbles and 3 percent cobbles; violently effervescent (25 percent calcium carbonate equivalent in the fine earth fraction); slightly alkaline (pH 7.8); clear wavy boundary. (10 to 20 inches thick)

2R--26 inches; hard limestone bedrock.

TYPE LOCATION: Clark County, Nevada; about 6 miles east and 12 miles north of Pahrump, Nevada; approximately 5 miles east and 5 miles south of Mount Stirling on the west side of the Spring Mountains; tentatively sectioned area 1,330 feet south and 2,560 feet west of the northeast corner of section 23, T. 18 S., R. 54 E.; USGS Mt. Stirling, NV 7.5 minute topographic quadrangle; 36 degrees, 22 minutes, 36.3 seconds north latitude and 115 degrees, 52 minutes, 41.8 seconds west longitude; UTM 11s, 0600618e 4026321n; NAD83.

RANGE IN CHARACTERISTICS:
Soil moisture - moist in late winter and spring, and periodically moist in the upper part following summer convection storms; ustic soil moisture regime bordering on aridic. In normal years the soil is dry in all parts of the moisture control section for four-tenths or more of the cumulative days per year when the soil temperature is higher than 5 degrees Celsius at a depth of 50 centimeters.

Soil temperature: 42 to 46 degrees F.
Depth to calcic horizon: 7 to 12 inches.
Depth to lithic contact: 20 to 40 inches.


Control section - Rock fragments: 35 to 70 percent, mainly gravel.
Clay content: 8 to 18 percent.

A horizon - Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3 moist.
Consistence: Soft or slightly hard, very friable or friable, nonsticky or slightly sticky, nonplastic or slightly plastic.
Reaction: Neutral through moderately alkaline.
Organic matter: 0.5 to 1.5 percent.

Bk1 horizon - Chroma: 3 or 4 moist.
Structure: Fine or medium.
Consistence: Very friable or friable.
Rock fragments: 35 to 65 percent, mainly gravel.
Effervescence: Slightly effervescent or strongly effervescent.
Reaction: Slightly alkaline or moderately alkaline.
Calcium carbonate equivalent of the fine earth fraction: 0 to 4 percent.
Organic matter: 0.5 to 1.5 percent.
Other features: Some pedons do not have iron stains or calcium carbonate films on bottoms of rock fragments.

Bk2 horizon - Value: 4 or 5 dry.
Chroma: 2 or 3 moist.
Texture: Loam or sandy loam.
Structure: Weak or moderate, fine through coarse.
Consistence: Soft or slightly hard, nonsticky or slightly sticky, nonplastic or slightly plastic.
Effervescence: Strongly effervescent or violently effervescent.
Reaction: Slightly alkaline or moderately alkaline.
Calcium carbonate equivalent of the fine earth fraction: 5 to 15 percent.
Organic matter: 1.0 to 2.0 percent.
Other features: Some pedons do not have iron stains.

Bk3 horizon - Value: 4 or 5 dry, 2 or 3 moist.
Texture: Loam or sandy loam.
Structure: Subangular blocky or massive.
Consistence: Nonsticky or slightly sticky, nonplastic or slightly plastic.
Reaction: Slightly alkaline or moderately alkaline.
Calcium carbonate equivalent of the fine earth fraction: 15 to 30 percent.
Organic matter: 1.0 to 2.0 percent.
Other features: Some pedons do not have iron stains.

COMPETING SERIES: These are the Barkelew, Bronec, Tabyago, Wildmount and Yampa series. Barkelew, Bronec, Wildmount and Yampa soils are very deep soils. Tabyago soils have rock fragments that are mostly channers from sandstone and shale.

GEOGRAPHIC SETTING: Devilsthumb soils are on backslopes of mountains. Slope ranges from 30 to 75 percent. These soils formed in colluvium from limestone and sandstone. Elevations are 6,900 to 8,700 feet. The climate is sub-humid continental, cool, with moist winters and common summer convection storms. The mean annual precipitation is 18 to 22 inches; mean annual air temperature is 40 to 44 degrees F., and the frost-free period is 60 to 95 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Fletcherpeak and Seralin soils. Fletcherpeak soils have a mollic epipedon, an argillic horizon and are shallow to bedrock. Seralin soils have a mollic epipedon and are shallow to bedrock.

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, ponderosa pine, currant, Charleston Rock goldenrod, Indian ricegrass and muttongrass.

DISTRIBUTION AND EXTENT: Southern Nevada; MLRA 30. These soils are not extensive.

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

SERIES ESTABLISHED: Clark County Area, Nevada, 2006. Proposed in Clark County Area, Nevada, 2003. The name is coined from Devils Thumb, located 0.6 miles north of Charleston Peak in the Spring Mountains.

REMARKS: Diagnostic horizons and features recognized in the profile are:
Ochric epipedon - 0 to 7 inches (A and B1 horizons).
Calcic horizon - 7 to 26 inches (Bk2 and Bk3 horizons).
Lithic contact - 26 inches (2R layer).
Particle-size control section - 10 to 26 inches (Part of the Bk2 and the Bk3 horizons).

Responsibility for this series was transferred from Davis to Phoenix 4/2015. The last revision to the series was 7/2006. ET

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National Cooperative Soil Survey
U.S.A.