LOCATION MAREPAS                 NV

Established Series
Rev. JBF/TM
12/2019

MAREPAS SERIES

The Marepas series consists of shallow over volcanic rock, well drained soils that formed in residuum and colluvium derived from tuff and volcanic rocks and volcanic ash. Marepas soils are on plateaus. Slopes are 4 to 50 percent. The mean annual precipitation is about 300 mm and the mean annual temperature is about 7.8 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy, mesic Aridic Lithic Argixerolls

TYPICAL PEDON: Marepas very gravelly mucky ashy sandy loam--rangeland (Colors are for dry soil unless otherwise noted.)

Oi--0 to 1 cm; slightly decomposed plant material; material consists mainly of juniper twigs and needles; about 10 percent of the surface is bare mineral soil. (0 to 2 cm thick)

A1--1 to 4 cm; very dark gray (10YR 3/1) very gravelly mucky ashy sandy loam, black (10YR 2/1) moist; moderate medium subangular blocky structure parting to weak fine granular; soft, very friable, nonsticky and nonplastic; many very fine roots; many very fine vesicular pores; 15 percent cobbles and 35 percent hard volcanic gravel; slightly alkaline (pH 7.4); abrupt wavy boundary. (3 to 8 cm thick)

A2--4 to 13 cm; dark grayish brown (10YR 4/2) very gravelly mucky ashy sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium granular structure; slightly hard, very friable, nonsticky and nonplastic; many very fine and few fine roots; many very fine vesicular pores; 15 percent cobbles and 35 percent hard volcanic gravel; slightly alkaline (pH 7.6); abrupt wavy boundary. (5 to 13 cm thick)

Bt--13 to 33 cm; brown (10YR 5/3) very cobbly ashy sandy clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure parting to moderate fine granular; slightly hard, very friable, moderately sticky and moderately plastic; common very fine and fine, many medium through very coarse roots; common very fine tubular pores; common faint and distinct clay films on faces of peds and lining pores; 30 percent cobbles and 20 percent hard volcanic gravel; slightly alkaline (pH 7.6); abrupt wavy boundary. (10 to 23 cm thick)

R--33 cm; hard andesitic tuff; few roots and some soil in some fractures.

TYPE LOCATION: Washoe County, Nevada; USGS Boulder Mountain 7.5 minute topographic quadrangle; about 1.5 miles west of Home Camp; about 600 feet south and 300 feet west of the northeast corner section 29, T. 40. and R. 19 E.; 41 degrees, 21 minutes, 47.9 seconds north latitude and 119 degrees, 52 minutes, 20.7 seconds west longitude, WGS84 Decimal Degrees 41.3633167 latitude, -119.8724167 longitude.

RANGE IN CHARACTERISTICS:

Soil moisture - Moist in winter and spring, dry from July through October; aridic moisture regime that borders on xeric.
Mean annual soil temperature - 8.3 to 10.0 degrees C.
Mollic epipedon thickness - 18 to 36 cm, includes the Bt horizon.
Depth to bedrock - 18 to 36 cm to a lithic contact.
Volcanic glass content - 35 to 60 percent in the coarse silt through fine sand fractions.
Profile reaction - Neutral or slightly alkaline.

Control section - Clay content: 12 to 18 percent.
Rock fragments: 35 to 50 percent mostly gravel and cobbles. Lithology of fragments are volcanic rocks such as andesite and tuff.

A horizons
Value: 2 or 3 moist.
Chroma: 1 through 3.

Bt horizon
Hue: 10YR or 7.5YR.
Value: 2 or 3 moist.
Chroma: 2 or 3.
Clay content: 20 to 25 percent.
Structure: Angular blocky or subangular blocky.
Rock fragments: 35 to 60 percent, mainly gravel and cobbles.
Consistence: Slightly hard or hard dry.

COMPETING SERIES: This is the Corbaley and Ocashe series. Corbaley soils have argillic horizons of fine sandy loam with 10 to 16 percent clay and are in drainageways with rare or occasional flooding. Ocashe soils have 60 to 80 percent rock fragments in the control section.

GEOGRAPHIC SETTING: Marepas soils are on plateaus. They formed in residuum and colluvium derived from andesitic tuff and volcanic rocks and volcanic ash. Slopes are 4 to 40 percent. Elevations range from 1,520 to 2,330 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 300 to 360 mm, mean annual temperature is 7.2 to 8.3 degrees C., and the frost-free period is 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Devada and Reywat soils. Devada soils are clayey. Reywat soils are loamy-skeletal.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; medium to high surface runoff; moderately rapid saturated hydraulic conductivity.

USE AND VEGETATION: Marepas soils are used for livestock grazing and wildlife habitat. The present vegetation is mainly Utah Juniper with an understory of Wyoming big sagebrush, bluebunch wheatgrass, Thurber's needlegrass, basin wildrye, and antelope bitterbrush.

DISTRIBUTION AND EXTENT: Western Washoe County, Nevada, Surprise Valley-Home Camp Area. MLRA 23. These soils are not extensive.

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

SERIES ESTABLISHED: Surprise Valley-Home Camp Area, California and Nevada, 2003.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - The zone from 1 to 33 cm (The A and Bt horizons).
Argillic horizon - The zone from 13 to 33 cm (The Bt horizon).
Lithic contact - The boundary at 33 cm (R boundary).
Particle-size control section and ashy substitute class with glassy mineralogy - The zone from the soil surface to 33 cm (The A1, A2 and Bt horizons).

Classification was updated to 11th edition on 07/2011 changed from Lithic Argixerolls to Aridic Lithic Argixerolls.

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National Cooperative Soil Survey
U.S.A.