LOCATION MOHOCKEN                NV

Established Series
Rev: DPC/JBF/WED
06/2016

MOHOCKEN SERIES

The Mohocken series consists of moderately deep, well drained soils that formed in residuum and colluvium derived from porphyritic latite. Mohocken soils are on mountain slopes. Slopes are 8 to 30 percent. Mean annual precipitation is about 380 mm and mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Fine, smectitic, frigid Typic Palexerolls

TYPICAL PEDON: Mohocken very gravelly loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 5 cm; grayish brown (10YR 5/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; common very fine and fine interstitial and tubular pores; 35 percent gravel, 10 percent cobbles; slightly alkaline (pH 7.6); clear smooth boundary. (5 to 10 cm thick)

A2--5 to 13 cm; brown (10YR 5/3) gravelly loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; common very fine and fine interstitial and tubular pores; 25 percent gravel, 5 percent cobbles; neutral (pH 7.2); clear smooth boundary. (5 to 15 cm thick)

A3--13 to 20 cm; yellowish brown (10YR 5/4) very gravelly loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine, few medium roots; common very fine and fine interstitial and few very fine tubular pores; 30 percent gravel, 5 percent cobbles; neutral (pH 7.0); abrupt smooth boundary. (3 to 8 cm thick)

Bt1--20 to 36 cm; brown (7.5YR 4/4) gravelly clay, brown (7.5YR 4/4) moist; moderate medium and coarse angular blocky structure; very hard, firm, sticky and plastic; common very fine, fine and few medium roots; few very fine to medium interstitial and tubular pores; 15 percent gravel; continuous distinct clay films on ped faces and lining pores; neutral (pH 7.0); clear smooth boundary. (15 to 38 cm thick)

Bt2--36 to 61 cm; brown (7.5YR 5/4) very gravelly sandy clay, brown (7.5YR 4/4) moist; weak fine and medium subangular blocky structure; hard, firm, sticky and plastic; common very fine and few fine and medium roots; few very fine interstitial and tubular pores; 35 percent gravel; common distinct and many faint clay films on ped faces and lining pores; neutral (pH 7.0); gradual wavy boundary. (20 to 30 cm thick)

Cr--61 cm; partially weathered latite, extremely hard when dry, hard when moist; few very fine roots, rock structure.

TYPE LOCATION: Esmeralda County, Nevada; about 2 miles north by northwest of Mohawk mine, about 200 feet south and 800 feet east of the apparent northwest corner of section 25, T. 2 S., R. 37 E.; USGS Mohawk Mine 7.5 minute topographical quadrangle; latitude 37 degrees 44 minutes 34.7 N and longitude 117 degrees 49 minutes 33.3 seconds W; WGS84 Decimal Degrees 37.7431667 latitude, -117.8261111 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter, spring and early summer, dry summer and fall but moist intermittently due to convection storms. Dry in all parts at least 45 consecutive days following summer solstice; typic xeric soil moisture regime.
Mean annual soil temperature: 6 to 8 degrees C.
Mollic epipedon thickness: 18 to 25 cm.
Depth to soft rock: 50 to 76 cm.

Particle-size control section -.Clay content: 35 to 50 percent.
Rock fragments: 20 to 35 (mostly 2-5 mm. in size)

A horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 through 4 dry, 2 or 3 moist.
Structure: Weak or moderate, very fine to medium subangular blocky. Consistence: Soft or slightly hard; very friable or friable, and nonsticky and nonplastic or slightly sticky and slightly plastic. Clay content: Averages l5 to 25 percent.
Rock fragments: Averages 35 to 50 percent, mostly gravel. Reaction: Neutral or slightly alkaline.
Other features: Thin less than 5 cm thick A and B or B and A horizons are in some pedons.

Bt1 horizon
Hue: 10YR or 7.5YR
Value: 4 or 5 dry.
Chroma: 3 or 4.
Clay content: 40 to 55 percent.
Rock fragments: 15 to 35 percent, mostly 2-5 mm. in size. Structure: Moderate or strong, medium or coarse subangular blocky, angular blocky or prismatic.
Consistence: Hard or very hard.

Bt2 horizon
Hue: 10YR or 7.5YR.
Value: 4, 5, or 6 dry, 3 or 4 moist.
Chroma: 3 or 4.
Texture: Clay loam, clay or sandy clay.
Clay content: 35 to 45 percent.
Rock fragments: 35 to 45 percent.
Structure: Weak fine or medium subangular blocky, or is massive.

COMPETING SERIES: These are the Bridgecreek, Coser, Deer Creek, Eoj, Goodington, Harkers, Lynnbow, Norcan, Rands, Starhope and Zumwalt series.

Bridgecreek and Coser soils have a mollic epipedon that is thicker than 25 cm. Deer Creek, Eoj, Goodington, Harkers, Lynnbow, Norcan and Rands soils lack bedrock within 100 cm. Starhope soils have mean annual soil temperatures of 4 to 7 degrees C. and the rock fragments within the Bt horizon decrease with depth. Zumwalt soils have a Bk horizon and have less than l5 percent rock fragments in the particle-size control section.

GEOGRAPHIC SETTING: Mohocken soils are on mountain slopes. These soils formed in residuum and colluvium from porphyritic latite. Slopes are 8 to 30 percent. Elevations are 2,290 to 2,870 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 360 to 460 mm; mean annual temperature is 6 to 7 degrees C., and the frost-free season is 60 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cucamungo and Ravenswood soils. Cucamungo soils are loamy-skeletal and are shallow to soft rock. Ravenswood soils are clayey-skeletal and are 76 to 100 cm deep to hard bedrock.

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

USE AND VEGETATION: Woodland, rangeland and wildlife habitat. The present vegetation is mainly singleleaf pinyon, Utah juniper, low sagebrush, green ephedra and prairie junegrass.

DISTRIBUTION AND EXTENT: Southwest Nevada. These soils are not extensive. MLRA29.

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

SERIES ESTABLISHED: Esmeralda County, Nevada, 1984.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 20 cm (A1, A2, A3 horizons)
Argillic horizon - The zone from about 20 cm to 61 cm (Bt1 and Bt2 horizons)
Paralithic contact - The boundary at 61 cm (Cr layer).
Particle-size control section - The zone from 20 cm to 61 cm (Bt1 and Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.