LOCATION SMALLCONE               NV+CA

Established Series
Rev. JVC/JBF
06/2017

SMALLCONE SERIES

The Smallcone series consists of very shallow, well drained soils that formed in residuum derived from hydrothermally altered andesitic rock. Smallcone soils are on hills and mountains. Slopes are 15 to 50 percent. The mean annual precipitation is about 280 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, active, nonacid, mesic, shallow Xeric Torriorthents

TYPICAL PEDON: Smallcone very gravelly coarse sandy loam--forest land. The surface is covered by approximately 50 percent gravel.

A--0 to 8 cm, very pale brown (10YR 7/4) very gravelly coarse sandy loam, yellowish brown (10YR 5/6) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine interstitial pores; 45 percent gravel; moderately acid (pH 5.6); clear smooth boundary. (5 to 10 cm thick)

C--8 to 15 cm, very pale brown (10YR 7/4) extremely gravelly coarse sandy loam, yellowish brown (10YR 5/6) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few very fine and medium roots; common very fine and medium interstitial pores; 50 percent gravel, 10 percent cobbles, and 5 percent stones; strongly acid (pH 5.4); abrupt wavy boundary. (5 to 15 cm thick)

Cr--15 cm; weathered and fractured hydrothermally altered andesite; pockets of clay loam and roots are in fractures of the bedrock; strongly acid (pH 5.5).

TYPE LOCATION: Washoe County, Nevada; in the Virginia Range about 4 miles east along the old Geiger Grade Road; approximately 113 feet south and 1,146 feet west of the northeast corner of section 1, T. 17 N., R. 20 E.; USGS Virginia City 7.5 minute topographic quadrangle; latitude 39 degrees 22 minutes 28 seconds N and longitude 119 degrees 40 minutes 55 seconds W; WGS84 Decimal Degrees 39.3744444 latitude, -119.6819444 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in late fall, winter, and spring, dry for the remainder of the year; Aridic moisture regime that borders on xeric.
Mean annual soil temperature: 8 to 11 degrees C.
Depth to bedrock: 10 to 25 cm to a paralithic contact. The paralithic materials below the contact are weathered volcanic rocks such as andesite.
Reaction: Strongly acid or moderately acid. The pH is 5.6 to 6.0 in at least one part of the control section which is usually the A horizon.

Particle-size control section - Clay content: 5 to 18 percent.
Rock fragments: 35 to 75 percent, mostly fine gravel. Lithology of fragments are hydrothermally altered volcanic rocks such as andesite or andesitic tuff.

A horizon
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 4 to 6, dry or moist.

C horizon
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 4 through 6, dry or moist.
Texture: Very gravelly coarse sandy loam or extremely gravelly sandy loam.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Smallcone soils are on hills and mountains. They typically occur on shoulder and backslope positions, but may also occur on narrow summits. These soils formed in residuum derived from hydrothermally altered andesitic rocks. The parent rock has undergone acid-sulfate alteration resulting in a soil parent material that is enriched in aluminum and silicon and depleted in bases. Slopes are 15 to 50 percent. Elevations range from 1,460 to 2,134 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 250 to 360 mm, mean annual temperature is 8 to 9 degrees C., and the frost-free period is 80 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Duco and Cagle soils. Duco soils are shallow to lithic contacts and have mollic epipedons and argillic horizons. Cagle soils are fine, moderately deep to paralithic contacts, and have mollic epipedons and argillic horizons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; very high surface runoff; rapid permeability; high saturated hydraulic conductivity.

USE AND VEGETATION: Smallcone soils are used for livestock grazing and forest land. The native vegetation is mainly an open forest canopy of Jeffrey pine or ponderosa pine with a sparse understory of bottlebrush squirreltail, antelope bitterbrush, and altered andesite buckwheat; This pedon is correlated to ecological site F026XY065NV, PIPO-EROR woodland.

DISTRIBUTION AND EXTENT: Western Nevada and eastern California. These soils are not extensive. MLRA 26.

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

SERIES ESTABLISHED: Washoe County, Nevada, South Part, 1980.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 15 cm (A and C horizons).
Paralithic contact - The boundary at 15 cm to underlying weathered bedrock (Cr layer).
Particle-size control section - The zone from the soil surface to 15 cm (A and C horizons).

The revision of December 2001 updated the taxonomic class from Loamy-skeletal, mixed, nonacid, mesic Lithic Xeric Torriorthents. The active cation exchange activity class is estimated based on available geologic information about the effects of acid-sulfate alteration on clay minerals. The contact at the base of the soil was changed from lithic to paralithic based on information from published soil surveys and personal experience of the original series author.

ADDITIONAL DATA: User pedon ID: 2006NV031001.
Previous authors and editors include JBF-OWB-WED.

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National Cooperative Soil Survey
U.S.A.