LOCATION MODEM                   NV

Established Series
Rev. JWM/CWL/TM/JBF
02/2012

MODEM SERIES

The Modem series consists of shallow to a duripan, well drained soils formed in alluvium derived from welded tuff and calcareous loess. Modem soils are on fan remnants. Slope ranges from 4 to 15 percent. The mean annual precipitation is about 330 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy, mesic, shallow Vitritorrandic Durixerolls

TYPICAL PEDON: Modem very gravelly ashy sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with approximately 40 percent gravel. Lithology of the fragments is welded tuff.

A--0 to 10 cm; grayish brown (10YR 5/2) very gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium roots; many very fine, common fine and few medium tubular pores; 40 percent gravel; slightly alkaline (pH 7.5); clear smooth boundary. (5 to 13 cm thick)

Btkq1--10 to 18 cm; brown (10YR 5/3) very gravelly ashy clay loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine, common fine, and few medium roots; many very fine, common fine and few medium tubular pores; 50 percent gravel; few faint clay films on faces of peds; common (10 percent) distinct secondary calcium carbonate and silica concretions on the bottom of rock fragments; violently effervescent; slightly alkaline (pH 7.6); clear smooth boundary.

Btkq2--18 to 25 cm; brown (10YR 5/3) very gravelly ashy clay loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine, and few medium roots; common very fine and fine tubular pores; 45 percent gravel, of which 20 percent are indurated pan fragments; common faint clay films on faces of peds; common (10 percent) distinct secondary calcium carbonate and silica concretions on the bottom of rock fragments; violently effervescent; slightly alkaline (pH 7.8); very abrupt smooth boundary. (Combined thickness of Btkq horizons is 15 to 46 cm.)

Bqkm1--25 to 64 cm; white (10YR 8/1) cemented material, light gray (10YR 7/1) moist; strong very thick platy structure; very rigid, indurated by secondary silica and calcium carbonate, with a 1 to 5 mm thick laminar cap; violently effervescent; gradual smooth boundary.

Bqkm2--64 to 117 cm; white (10YR 8/1) cemented material, light gray (10YR 7/1) moist; massive; very rigid, indurated by secondary silica and calcium carbonate; violently effervescent; clear smooth boundary. (Combined thickness of Bqkm horizons is 50 to 127 cm.)

Bkqy--117 to 152 cm; light gray (10YR 7/2) extremely cobbly ashy sandy loam, brown (10YR 5/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; many very fine interstitial pores; 30 percent gravel, 40 percent cobbles and 10 percent stones; few distinct secondary calcium carbonate and silica concretions around rock fragments; few faint secondary gypsum concretions on the bottom of rock fragments; violently effervescent; strongly alkaline (pH 8.5).

TYPE LOCATION: Lincoln County, Nevada; located about 2 miles northwest of Dutch John Mountain and 50 feet south of the jeep trail; USGS Dutch John Mtn. 7.5 minute topographic quadrangle; latitude 38 degrees 28 minutes 42 seconds N, and longitude 114 degrees 42 minutes 14 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in winter and spring, dry summer and fall; intermittently moist for 10 to 20 days cumulative from July through September due to convection storms; aridic soil moisture regime bordering on xeric.
Soil temperature: 8 to 11 degrees C.
Mollic epipedon thickness: 25 to 36 cm.
Thickness of the argillic horizon: 15 to 46 cm.
Depth to the duripan: 25 to 50 cm.
Thickness of the duripan: 50 to 127 cm.
Mineralogy - 30 to 50 percent volcanic glass and glass aggregates in the 0.2 to 2 mm fraction.

Particle-size control section; Clay content: 18 to 30 percent.
Rock fragments: 35 to 60 percent. Lithology of the fragments is welded tuff and indurated pan fragments.

A horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Effervescence: Noneffervescent through slightly effervescent.
Calcium carbonate equivalent: 0 to 5 percent in the material less than 2 mm.
Reaction: Slightly alkaline or moderately alkaline.

Btkq horizons
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Texture: Ashy loam, ashy clay loam, ashy sandy clay loam.
Clay content: 20 to 32 percent.
Rock fragments: 35 to 60 percent, mainly gravel.
Consistence: Slightly hard to hard, dry.
Effervescence: Slightly effervescent through violently effervescent.
Calcium carbonate equivalent: 5 to 10 percent in the material less than 2 mm.
Other features: Cementation by secondary silica and calcium carbonate as pendants or as weathered fragments of cemented material.
Reaction: Slightly alkaline or moderately alkaline.

Bqkm horizons
Value: 7 or 8 dry, 7 or 8 moist.
Chroma: 1 through 3, dry or moist.

Bkqy horizon (when present)
Value: 6 through 8 dry, 4 through 7 moist.
Chroma: 1 through 3, dry or moist.
Rock fragments: 60 to 80 percent, mainly gravel and cobbles.
Other features: Secondary calcium carbonate and silica present as concretions on rock fragments.
Calcium carbonate equivalent: 10 to 20 percent in the material less than 2 mm.
Gypsum content: 3 to 5 percent.
Reaction: Moderately alkaline or strongly alkaline.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Modem soils are on fan remnants. These soils formed in alluvium from welded tuff and calcareous loess. The climate is dry and semiarid. Slopes range from 4 to 15 percent. Elevations are 1,845 to 2,525 meters. The mean annual precipitation is about 300 to 360 mm. Mean annual temperature is about 7 to 10 degrees C and the frost-free period is about 90 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ravendog and Jarab series. Ravendog soils occur on inset fan and drainageway positions, and do not have a duripan or an argillic horizon. Jarab soils occur on fan remnants and do not have an argillic horizon.

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

USE AND VEGETATION: Modem soils are used for livestock grazing and wildlife habitat. The potential native vegetation includes bluebunch wheatgrass, Thurbers needlegrass, needleandthread, muttongrass, mountain big sagebrush, and antelope bitterbrush. This pedon is correlated to Ecological Site R028AY088NV, Gravelly Clay 12-14" P.Z.

DISTRIBUTION AND EXTENT: Eastern Nevada. The soils are not extensive. MLRA 28A.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Lincoln County, Nevada, North Part; June, 2004. The name is coined.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 25 cm (A, Btkq1, and Btkq2 horizons).
Argillic horizon - The zone from 10 inches to 25 cm (Btkq1 and Btkq2 horizons).
Duripan - The zone from 25 to 117 cm (Bqkm1 and Bqkm2 horizons).
Particle-size control section - The zone from the soil surface to 25 cm (A, Btkq1 and Btkq2 horizons).

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National Cooperative Soil Survey
U.S.A.