LOCATION STOPATOE                NV

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

STOPATOE SERIES

The Stopatoe series consists of moderately deep, well drained soils that formed in colluvium and residuum derived from volcanic rocks. Stopatoe soils are on mountains. Slopes are 4 to 30 percent. The mean annual precipitation is about 400 mm and the mean annual temperature is about 4 degrees C.

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

TYPICAL PEDON: Stopatoe gravelly loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partly covered by 25 percent gravel.

A1--0 to 20 cm; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; common very fine interstitial and tubular pores; 25 percent gravel; neutral (pH 6.8); abrupt smooth boundary. (8 to 20 cm thick)

A2--20 to 36 cm; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; 25 percent gravel and 5 percent cobbles; neutral (pH 6.8); clear smooth boundary. (10 to 30 cm thick)

Bt1--36 to 53 cm; yellowish brown (10YR 5/4) very gravelly loam, dark yellowish brown (10YR 3/4) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine and fine roots; common very fine, few fine and medium tubular pores; few faint clay films on faces of peds and lining pores; 30 percent gravel and 5 percent cobbles; neutral (pH 6.8); clear smooth boundary. (8 to 25 cm thick)

Bt2--53 to 79; brown (7.5YR 5/4) very gravelly clay loam, brown (7.5YR 4/4) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few very fine and fine roots; common very fine and few fine tubular pores; common distinct clay films on faces of peds and lining pores; 30 percent gravel and 5 percent cobbles; neutral (pH 7.0); abrupt smooth boundary. (13 to 50 cm thick)

Cr--79 to 104 cm; soft, weathered rhyolitic tuff.

TYPE LOCATION: Nye County, Nevada; on the Toiyabe National Forest in the Monitor Range southeast of Hunts Canyon and above the head of Big Cottonwood Canyon; about 2,600 feet north and 200 feet west of the southeast corner of section 7, T. 47 E., R. 6 N. USGS McCann Canyon 7.5 minute topographic quadrangle; latitude 38 degrees 23 minutes 11 seconds N and longitude 116 degrees 44 minutes 44 seconds W; WGS84 Decimal Degrees 38.3865000 latitude, -116.7455556 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section from mid-October through June, dry in summer and early fall (continuously dry for 60 to 90 days); xeric moisture regime.
Mean annual soil temperature: 4 to 7 degrees C.
Mean summer soil temperature: 12 to 15 degrees C.
Mollic epipedon thickness: 25 to 40 cm.
Depth to base of argillic horizon: 50 to 100 cm.
Depth to bedrock: 50 to 100 cm to a paralithic contact. The paralithic materials below the contact are weathered rhyolitic tuff.

Particle-size control section - Clay content: 20 to 35 percent.
Sand content: 30 to 45 percent.
Rock fragments: 35 to 45 percent, mainly gravel about one half of which are fine (2 to 5 mm. in diameter) and 0 to 5 percent cobbles. Lithology of fragments is volcanic rocks such as tuff or rhyolite.

A horizons
Hue: 7.5YR or 10YR.
Chroma: 2 or 3, dry or moist.
Organic matter content: 1 or 2 percent.

Bt horizons
Hue: 7.5YR or 10YR.
Chroma: 3 or 4, dry or moist.
Texture: Very gravelly loam or very gravelly clay loam.

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

Boneyard soils have more than 60 percent rock fragments in the particle-size control section. Tagum soils have 50 to 65 percent sand in the particle-size control section. Chamberlain, Crandall, Ezbin, Forsey, Fourme, Jackflat, Packer and Zeebar soils are deeper than 100 cm. Cowlow soils have a calcic horizon within 28 to 76 cm. Itwo and Toquima soils are moderately deep to lithic contacts. Scuffe soils have more than 15 percent cobbles in the particle-size control section. Winada soils have paralithic materials composed of weathered sedimentary rocks such as sandstone.

GEOGRAPHIC SETTING: Stopatoe soils are on mountains. They typically occur on summit and shoulder positions. They formed in colluvium and residuum derived from volcanic rocks. Slopes are 4 to 30 percent. Elevations range from 2,505 to 3,510 meters. The climate is semiarid with cold, moist winters and cool, dry summers. The mean annual precipitation is 360 to 460 mm, mean annual temperature is 3 to 6 degrees C, and the frost-free period is 30 to 60 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Foxvire and Hackwood soils and the competing Packer soil. Foxvire soils are coarse-loamy and very deep. Hackwood soils are fine-loamy and very deep.

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

USE AND VEGETATION: Stopatoe soils are used for livestock grazing and wildlife habitat. The present vegetation is mainly stunted mountain big sagebrush, western wheatgrass, and Letterman's needlegrass.

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, 1994.

REMARKS: Further study is needed on this series to determine the influence of volcanic ash on soil properties and taxonomic classification. It may classify in the Vitrandic subgroup of Argicryolls and have isotic mineralogy and ashy texture modifiers.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 36 cm (A1 and A2 horizons).
Argillic horizon - The zone from 36 to 79 cm (Bt1 and Bt2 horizons).
Paralithic contact - The boundary at 79 cm to underlying soft, weathered bedrock (Cr layer).
Particle-size control section - The zone from 36 to 79 cm (Bt1 and Bt2 horizons).

ADDITIONAL DATA: Characterization data for a similar soil is available as SSL pedon 78P0566.

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National Cooperative Soil Survey
U.S.A.