LOCATION ALTA                    NV

Established Series
Rev. DLJ-RLB-JVC-JBF
12/2019

ALTA SERIES

The Alta series consists of deep, somewhat excessively drained soils that formed in colluvium and residuum derived from granitic rock. Alta soils are on mountains. Slopes are 30 to 75 percent. The mean annual precipitation is about 460 mm and the mean annual temperature is about 4 degrees C.

TAXONOMIC CLASS: Sandy-skeletal, mixed Pachic Haplocryolls

TYPICAL PEDON: Alta very bouldery coarse sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 25 percent boulders and 2 percent with cobbles.

Oi--0 to 3 cm; slightly decomposed plant material from curlleaf mountainmahogany leaves and twigs. (1.5 to 5 cm thick)

A1--3 to 10 cm; dark grayish brown (10YR 4/2) very bouldery coarse sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and few fine roots; many very fine interstitial pores; 25 percent boulders and 15 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (7 to 25 cm thick)

A2--10 to 43 cm; dark grayish brown (10YR 4/2) very bouldery coarse sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure: soft, very friable, nonsticky and nonplastic; common very fine, fine and medium roots; many very fine tubular pores; 20 percent boulders and 15 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (25 to 46 cm thick)

C1--43 to 51 cm; pale brown (10YR 6/3) very stony loamy coarse sand, brown (10YR 4/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; common very fine and few fine roots; common very fine interstitial pores; 30 percent stones, 2 percent cobbles, and 20 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (10 to 36 cm thick)

C2--51 to 127 cm; pale brown (10YR 6/3) very stony loamy coarse sand, brown (10YR 4/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine roots; many very fine interstitial pores; 30 percent stones and 20 percent gravel; neutral (pH 6.6); clear smooth boundary. (30 to 80 cm thick)

Cr--127 to 137 cm; weathered granitic rock.

TYPE LOCATION: Humboldt County, Nevada; about 2 miles southeast of Knott Creek Reservoir in the Pine Forest Range; approximately 2,700 feet east and 200 feet north of the projected southwest corner of section 10, T. 43 N., R. 28 E.; USGS Knott Creek 7.5 minute topographic quadrangle; latitude 41 degrees 39 minutes 42 seconds N and longitude 118 degrees 45 minutes 21 seconds W; WGS84 Decimal Degrees 41.6616667 latitude, -118.7558333 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter, spring and early summer, dry mid-July through early October; xeric soil moisture regime that borders on aridic.
Mean annual soil temperature: 4 to 5 degrees C.
Mean summer soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 40 to 60 cm.
Depth to bedrock: 100 to 150 cm to a paralithic contact. The paralithic materials below the contact are weathered granitic rock.

Particle-size control section: Clay content: 5 to 10 percent.
Rock fragments: 35 to 60 percent, dominantly stones and boulders. Lithology of fragments is granitic rocks such as granodiorite or granite.

A horizon
Value: 3 or 4 dry, 2 or 3 moist.
Chroma: 1 or 2, dry or moist.
Clay content: 5 to 10 percent.
Reaction: Slightly acid or neutral.
Organic matter content: 2 to 5 percent.

C horizon
Chroma: 2 or 3, dry or moist.
Texture: Loamy coarse sand, thin subhorizons of coarse sandy loam are in the upper part of some pedons.
Clay content: 5 to 10 percent.
Rock fragments: 35 to 60 percent, dominantly stones and boulders.
Reaction: Slightly acid or neutral.

COMPETING SERIES: These are the Hastee and Waterpeak series.

Hastee soils do not have thin Oi horizons, have mean summer soil temperature of 12 to 15 degrees C., and have mean annual soil temperature of 5 to 7 degrees C. Waterpeak soils are very deep.

GEOGRAPHIC SETTING: Alta soils are on mountains. The typically occur on north-facing backslope positions. These soils formed in colluvium and residuum derived from granitic rock. Slopes are 30 to 75 percent. Elevations range from 2,075 to 2,595 meters. The climate is subhumid with cold, moist winters and cool, dry summers. The mean annual precipitation is 360 to 500 mm, the mean annual temperature is 3 to 5 degrees C, and the frost-free period is 30 to 60 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aycab and Tosp soils. Aycab soils are coarse-loamy and are moderately deep to paralithic contacts. Tosp soils are coarse-loamy and are deep or very deep.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat excessively drained; medium surface runoff; high saturated hydraulic conductivity.

USE AND VEGETATION: Alta soils are used for rangeland and wildlife habitat. The present vegetation is mainly curlleaf mountainmahogany. Other important species are mountain big sagebrush, antelope bitterbrush, big squirreltail, muttongrass, and needlegrasses.

DISTRIBUTION AND EXTENT: Northwestern Nevada. These soils are not extensive with about 7,400 acres of the series mapped to date. MLRA 23.

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

SERIES ESTABLISHED: Humboldt County (West Part), Nevada, 1994.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Organic soil material - The zone from the soil surface to 3 cm (Oi horizon).
Mollic epipedon - The zone from the soil surface to 43 cm (Oi, A1, and A2 horizons).
Paralithic contact - The boundary at 127 cm to underlying soft, weathered bedrock (Cr layer).
Particle-size control section - The zone from 25 to 100 cm (C1 horizon and parts of the A2 and C2 horizons).

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National Cooperative Soil Survey
U.S.A.