LOCATION SECREPASS               NV

Established Series
Rev. PWB/RLB/JBF
11/2019

SECREPASS SERIES

The Secrepass series consists of very deep, well drained soils that formed in alluvium derived from mixed rocks. The Secrepass soils are on fan piedmont remnants. Slopes are 4 to 15 percent. The mean annual precipitation is about 460 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Typic Palexerolls

TYPICAL PEDON: Secrepass gravelly loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 40 percent gravel and 5 percent with cobbles.

A1--0 to 8 cm; dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; weak thick platy parting to moderate fine subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, few fine and medium roots; common very fine and few fine interstitial pores; 25 percent gravel; neutral (pH 6.8); clear smooth boundary. (5 to 13 cm thick)

A2--8 to 18 cm; dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium and coarse roots; common very fine and few fine, medium and coarse interstitial and tubular pores; 15 percent gravel; neutral (pH 6.8); abrupt smooth boundary. (10 to 20 cm thick)

Bt--18 to 36 cm; brown (10YR 5/3) gravelly clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine, few fine and medium roots; many very fine and few fine and medium interstitial and tubular pores; common faint clay films on faces of peds and few faint lining pores; 25 percent gravel, 5 percent cobbles; neutral (pH 6.6); abrupt smooth boundary. (13 to 20 cm thick)

2Bt1--36 to 58 cm; brown (10YR 5/3) very gravelly clay, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine, few fine and medium roots; many very fine, few fine, medium and coarse tubular pores; many distinct clay films on faces of peds and lining pores; 30 percent gravel, 10 percent cobbles; neutral (pH 6.8); clear smooth boundary. (20 to 25 cm thick)

2Bt2--58 to 79 cm; dark yellowish brown (10YR 4/6) very gravelly clay, dark yellowish brown (10YR 4/6) moist; strong coarse prismatic parting to strong coarse angular blocky; hard, firm, very sticky and very plastic; few very fine to coarse roots; many very fine, few fine, medium and coarse tubular pores; many distinct clay films on faces of peds and lining pores; few pressure faces; 30 percent gravel, 10 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (18 to 28 cm thick)

3C--79 to 152 cm; very pale brown (10YR 7/3) extremely gravelly sandy loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, slightly sticky and nonplastic; few very fine and fine roots; common very fine interstitial pores; 45 percent gravel, 15 percent cobbles and 5 percent stones; slightly acid (pH 6.4).

TYPE LOCATION: Elko County, Nevada; Approximately 5 miles north of Arthur, Nevada; 600 feet south and 2,400 feet west of the northeast corner of section 3, T. 34 N., R. 60 E.; USGS Secret Valley 7.5 minute topographic quadrangle; latitude 40 degrees 51 minutes 47 seconds N and longitude 115 degrees 11 minutes 18 seconds W; WGS84 Decimal Degrees 40.8630472 latitude, -115.1883333 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist, moist in winter and spring, dry in late summer and fall; typic xeric soil moisture regime.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 30 to 40 cm and includes upper part of argillic horizon.
Depth to abrupt textural boundary: 18 to 25 cm.
Depth to base of argillic: 75 to 100 cm.
Reaction: Slightly acid or neutral.

Particle-size control section - Clay content: Averages 35 to 50 percent.
Rock fragments: Averages 35 to 60 percent.

A horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3.

Bt horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3.
Texture: Gravelly clay loam, very gravelly clay loam.
Clay content: 30 to 40 percent.
Rock fragments: 25 to 40 percent gravel, 0 to 5 percent cobbles.

2Bt horizons
Value: 4 or 5 dry.
Chroma: 3 through 6.
Texture: Very gravelly clay, very cobbly clay.
Clay content: 40 to 60 percent.
Rock fragments: 25 to 45 percent gravel and 5 to 15 percent cobbles.
Structure: Prismatic or subangular blocky.
Consistence: Slightly hard or hard dry, friable or firm moist, sticky or very sticky and plastic or very plastic wet.
Other features: Black (10YR 2/1) organic stains on ped faces and lining pores.

COMPETING SERIES: These are the Amboat, Aninto, Durfee, Ebic, and Ziram.

Amboat soils have 60 to 85 percent stones in the Bt horizons and have a combined A and Bt thickness of 100 to more than 150 cm. Aninto soils have a combined A and Bt horizon thickness of more than 100 cm and have a 2Bk horizon. Durfee soils have a combined A and Bt horizon thickness of more than 150 cm, and clay content that does not decrease by as much as 20 percent of the maximum within 150 cm. Ebic soils are 50 to 75 cm to bedrock. Ziram soils have 18 to 28 cm thick mollic epipedons and are 40 to 70 cm to secondary carbonates,

GEOGRAPHIC SETTING: Secrepass soils are on fan piedmont remnants. These soils formed in alluvium derived from mixed rocks. Slopes are 4 to 15 percent. Elevations are 1,895 to 2,135 meters. The climate is cool, semiarid with cool moist winters and warm dry summers. The mean annual precipitation is 410 to 500 mm, mean annual temperature is 4 to 7 degrees C, and the frost-free season is 80 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bullump, Cleavage, Krenka and Welch series.

Bullump and Krenka soils have mollic epipedons greater than 50 cm thick. Cleavage soils are shallow to bedrock. Welch soils are very poorly drained.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; rapid runoff; low saturated hydraulic conductivity.

USE AND VEGETATION: Rangeland and wildlife habitat. The present vegetation is mainly low sagebrush, Letterman needlegrass, Idaho fescue and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: Northeast Nevada. MLRA 25. These soils are not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES PROPOSED: Elko County, Nevada, Southeast Part. 1992. The name is coined from Secret Pass.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 36 cm (A1, A2 and Bt horizons).
Argillic horizon - The zone from 18 to 79 cm (Bt, 2Bt1 and 2Bt2 horizons).
Abrupt Boundary - The zone at 18 cm (Abrupt boundary between A2 and Bt horizons).
Particle-size control section - The zone from 18 to 68 cm (Bt, 2Bt1 and part of 2Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.