LOCATION ITWO                    NV

Tentative Series
Rev. JBF-TM-JVC
11/2016

ITWO SERIES

The Itwo series consists of moderately deep, well drained soils that formed in colluvium and residuum derived from quartzite. Itwo soils are on mountains. Slopes are 30 to 75 percent. The mean annual precipitation is about 360 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Xeric Argicryolls

TYPICAL PEDON: Itwo very gravelly loam--rangeland. (Colors are for dry soil unless otherwise noted.) The surface is covered with 45 percent gravel.

A--0 to 20 cm; grayish brown (10YR 5/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; common fine tubular pores; 40 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (10 to 25 cm thick)

2A--20 to 38 cm; grayish brown (10YR 5/2) extremely cobbly loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; common fine tubular pores; 30 percent gravel and 35 percent cobbles; neutral (pH 6.8); clear smooth boundary. (10 to 25 cm thick)

2Bt1--38 to 53 cm; light yellowish brown (10YR 6/4) extremely cobbly loam, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; common fine tubular pores; common faint clay films lining pores and coating sand grains; 35 percent gravel and 30 percent cobbles; neutral (pH 6.8); clear smooth boundary. (10 to 25 cm thick)

2Bt2--53 to 71 cm; pale brown (10YR 6/3) extremely cobbly loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and common fine roots in pockets; few fine tubular pores; few faint clay films lining pores and coating sand grains; 35 percent gravel and 35 percent cobbles; neutral (pH 6.6); clear smooth boundary. (0 to 25 cm thick)

R--71 cm; fractured quartzite.

TYPE LOCATION: Nye County, Nevada; on the Toiyabe National Forest in the Toiyabe Range south of San Juan Creek; about 2,400 feet north and 2,200 feet west of the southeast corner of section 3, T. 14 N., R. 42 E.; USGS Millett Ranch 7.5 minute topographic quadrangle; latitude 39 degrees 06 minutes 16 seconds N and longitude 117 degrees 14 minutes 29 seconds W; WGS84 Decimal Degrees 39.1045611 latitude, -117.2414000 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section from late fall through late spring, dry from early summer through early fall; xeric moisture regime that borders on aridic.
Mean annual soil temperature: 6 to 8 degrees C.
Mean summer soil temperature: 9 to 14 degrees C.
Mollic epipedon thickness: 25 to 38 cm.
Depth to base of argillic horizon: 50 to 100 cm.
Depth to bedrock: 50 to 100 cm to a lithic contact.
Reaction: Slightly acid or neutral.

Particle-size control section - Clay content: 18 to 27 percent.
Rock fragments: 60 to 80 percent, mainly cobbles and gravel. Lithology of fragments are quartzite.

A1 horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3 moist.
Organic matter content: 2 to 5 percent.

2A2 horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3 moist.
Organic matter content: 2 to 4 percent.

2Bt horizons
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4 moist.
Texture: Extremely cobbly loam or extremely cobbly sandy clay loam.

COMPETING SERIES: These are the Boneyard, Chamberlain, Cowlow, Crandall, Ezbin, Forsey, Fourme, Jackflat, Packer, Scuffe, Stopatoe, Successloop, Tagum, Toquima, Winada, and Zeebar series.

Boneyard soils have argillic horizons hat are slightly alkaline or moderately alkaline. Cowlow soils have calcic horizons at 28 to 76 cm. Scuffe soils have less than 60 percent rock fragments in the particle-size control section. Stopatoe, Tagum, and Winada soils are moderately deep to paralithic contacts. Chamberlain, Ezbin, Forsey, Fourme, Successloop and Zeebar soils are very deep. Crandall and Jackflat soils are deep. Packer soils are deep and very deep to lithic contacts. Toquima soils have surface Oi horizons, have C horizons below the argillic horizons, and have depth to base of the argillic horizon of 25 to 50 cm.

GEOGRAPHIC SETTING: Itwo soils are on mountains. They typically occur on backslope positions. These soils formed in colluvium and residuum derived from quartzite. Slopes are 30 to 75 percent. Elevations range from 2,505 to 2,930 meters. The climate is semiarid with cold, moist winters and cool, dry summers. The mean annual precipitation is 300 to 400 mm, mean annual temperature is 5 to 7 degrees C., and frost-free period is 50 to 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Labshaft and Tusel soils. Labshaft soils are shallow to lithic contacts. Tusel soils are deep to lithic contacts and have thick mollic epipedons.

DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; moderate permeability; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Itwo soils are used for livestock grazing and wildlife habitat. The present vegetation is mainly mountain big sagebrush, snowberry, Idaho fescue, and mountain brome.

DISTRIBUTION AND EXTENT: Central Nevada. These soils are not extensive. MLRA 28B.

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

SERIES PROPOSED: Nye County (Toiyabe National Forest), Nevada, 1997.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 38 cm (A1 and 2A2 horizons).
Argillic horizon - The zone from 38 to 71 cm (2Bt1 and 2Bt2 horizons).
Lithic contact - The boundary at 71 cm to underlying hard bedrock (R layer).
Particle-size control section - The zone from 38 to 71 cm (2Bt1 and 2Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.