LOCATION ZORROMOUNT              NV

Established Series
Rev. SES/JBF/TM/JVC
01/2020

ZORROMOUNT SERIES

The Zorromount series consists of very deep, well drained soils formed in colluvium derived from volcanic rocks. Zorromount soils are on mountains. Slopes are 4 to 50 percent. The mean annual precipitation is about 400 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy Vitrandic Haplocryolls

TYPICAL PEDON: Zorromount gravelly ashy mucky fine sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with 45 percent gravel and 5 percent cobbles and approximately 5 cm of undecomposed leaves and twigs.

A1--0 to 3 cm; very dark grayish brown (10YR 3/2) gravelly ashy mucky fine sandy loam, black (10YR 2/1) moist; moderate medium subangular blocky structure parting to moderate fine granular; soft, very friable, nonsticky and nonplastic; many very fine roots; many very fine tubular and interstitial pores; 30 percent volcanic gravel; moderately acid (pH 5.8); abrupt wavy boundary. (3 or 5 cm thick)

A2--3 to 13 cm; dark brown (10YR 3/3) very gravelly ashy sandy loam, black (10YR 2/1) moist; moderate medium subangular blocky structure parting to moderate fine granular; soft, very friable, nonsticky and nonplastic; many very fine, common fine through very coarse roots; many very fine and few fine tubular pores; 35 percent gravel and 5 percent cobbles; slightly acid (pH 6.2); clear wavy boundary. (5 to 13 cm thick)

A3--13 to 28 cm; dark grayish brown (10YR 4/2) very gravelly ashy sandy loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky structure parting to moderate fine granular; soft, very friable, nonsticky and nonplastic; many very fine and fine, common medium through very coarse roots; many very fine tubular and interstitial pores; 45 percent gravel and 5 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (13 to 20 cm thick)

Bw1--28 to 46 cm; light brownish gray (10YR 6/2) extremely gravelly ashy sandy loam, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine through very coarse roots; many very fine and few fine tubular pores; 60 percent gravel and 5 percent cobbles; slightly acid (pH 6.2); abrupt wavy boundary. (15 to 40 cm thick)

Bw2--46 to 79 cm; light brownish gray (10YR 6/2) extremely gravelly ashy fine sandy loam, brown (10YR 4/3) moist; moderate fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine through very coarse roots; many very fine and common fine tubular pores; 65 percent gravel and 5 percent cobbles; 5 percent 5 to 15 mm strong brown (7.5YR 5/6) and brown (7.5YR 5/4) masses of iron accumulation on faces of peds and on rock fragments, strong brown (7.5YR 4/6) moist; slightly acid (pH 6.2); abrupt wavy boundary. (0 to 40 cm thick)

C--79 to 152 cm; light gray (10YR 7/2) extremely gravelly ashy fine sandy loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine, common medium through coarse roots; many very fine and common fine tubular pores; 55 percent gravel and 25 percent cobbles; 2 percent 5 to 15 mm strong brown (7.5YR 5/6) and brown (7.5YR 5/4) masses of iron accumulation on faces of peds and on rock fragments, strong brown (7.5YR 4/6) moist; slightly acid (pH 6.4).

TYPE LOCATION: Washoe County, Nevada; in the Granite Range about 2.5 miles east of Fox Mountain; approximately 1,300 feet north and 2,700 feet east of the southwest corner of section 4, T. 36 N., R. 22 E.; USGS Fox Mountain 7.5 minute topographic quadrangle; latitude 41 degrees 01 minutes 35.6 seconds N and longitude 119 degrees 30 minutes 48.7 seconds W; WGS84 Decimal Degrees 41.0265556 latitude, -119.5135278 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist, moist in winter and spring, dry July through October; xeric soil moisture regime that borders on aridic.
Mean annual soil temperature: 7 to 8 degrees C.
Mean summer soil temperature: 12 to 15 degrees C.
Mollic epipedon thickness: 25 to 38 cm.
Depth to base of cambic horizon: 64 to 89 cm.
Volcanic glass content: 60 to 95 percent in coarse silt through fine sand fractions.

Particle-size control section - Clay content: 8 to 15 percent.
Rock fragments: 60 to 80 percent, mainly gravel and some cobbles. Lithology is volcanic rocks such as tuff and andesite.

A horizons
Value: 3 through 5 dry.
Chroma: 1 through 3, dry or moist.
Reaction: Moderately acid or slightly acid.
Organic matter content: 2 to 16 percent.

Bw horizons
Value: 5 or 6 dry.
Chroma: 2 or 3, dry or moist.
Texture: Extremely gravelly ashy fine sandy loam or extremely gravelly ashy sandy loam.

C horizon
Value: 6 or 7 dry, 3 through 5 moist.
Chroma: 2 through 4, dry or moist.
Texture: Extremely gravelly ashy fine sandy loam or extremely gravelly ashy sandy loam.
Reaction: Slightly acid or neutral.

COMPETING SERIES: These are the Cherpi, Greengrove and Nyman series.

Cherpi soils are deeper than 100 cm to the C horizon. Greengrove soils are intermittently moist in the upper part for 10 to 20 days cumulative due to convection storms between July and September. Nyman soils are moderately deep to lithic contacts.

GEOGRAPHIC SETTING: Zorromount soils are on mountains. They typically occur on footslope and backslope positions. They formed in colluvium derived from volcanic rocks. Slopes are 4 to 50 percent. Elevations range from 1,750 to 2,500 meters. The mean annual precipitation is 360 to 460 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 60 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ashtre, Cavin, Hutchley, and Nutzan soils. Ashtre soils are ashy, moderately deep to paralithic contacts, have argillic horizons, and have an aridic moisture regime. Cavin soils have an aridic moisture regime. Hutchley soils are loamy-skeletal, shallow to lithic contacts, and have argillic horizons. Nutzan soils are moderately deep to paralithic contacts and have an aridic moisture regime. In addition, all of these soils have frigid temperature regime.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; low or medium surface runoff; high saturated hydraulic conductivity.

USE AND VEGETATION: Zorromount soils are used for livestock grazing and wildlife habitat. The present vegetation is dominantly curlleaf mountainmahogany, needlegrass, Idaho fescue, bluegrass, and mountain big sagebrush. Snowpocket phases have snowbrush ceanothus, needlegrass, and mulesear wyethia.

DISTRIBUTION AND EXTENT: Northwestern Nevada. The soils are not extensive with about 5,100 acres of the series mapped to date. MLRA 23.

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

SERIES ESTABLISHED: Surprise Valley-Home Camp Area, California and Nevada, 2006. The name is coined from Fox Mountain.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 28 cm (A1, A2, and A3 horizons).
Cambic horizon - The zone from 28 to 79 cm (Bw1 and Bw2 horizons).
Particle-size control section and ashy-skeletal substitute class with glassy mineralogy - The zone from 25 to 100 cm (Bw1 and Bw2 horizons and parts of the A3 and C horizons).

ADDITIONAL DATA: Volcanic glass content determined locally by optical grain counts using a polarizing petrographic microscope.

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National Cooperative Soil Survey
U.S.A.