LOCATION TREADWELL               NV

Established Series
Rev. BAG/TM/JBF
07/2016

TREADWELL SERIES

The Treadwell series consists of very shallow to a duripan, well drained soils that formed in calcareous loess over alluvium derived from welded tuff and basalt. The Treadwell soils are on fan remnants and partial ballenas. Slopes range from 4 to 30 percent. The mean annual precipitation is about 180 mm and the mean annual temperature is about 11 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic, shallow Typic Haplodurids

TYPICAL PEDON: Treadwell gravelly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The surface is covered with 55 percent gravel of which 25 percent is broken pan fragments, 10 percent cobbles and 5 percent stones. Lithology is mainly welded tuff and basalt. Exposed parts of the rock fragments have a thin coat of desert varnish and secondary calcium carbonate pendants on the bottoms.

A--0 to 13 cm; pale brown (10YR 6/3) gravelly sandy loam, brown (10YR 4/3) moist; moderate thin platy structure; soft, very friable, nonsticky and nonplastic; few fine and medium roots; common very fine and fine irregular pores; 30 percent gravel; calcium carbonate equivalent is 13 percent; violently effervescent; strongly alkaline (pH 8.5); abrupt smooth boundary. (5 to 15 cm thick)

Bqk--13 to 20 cm; light gray (10YR 7/2) extremely gravelly sandy loam, brown (10YR 5/3) moist; strong thick platy structure; slightly hard, very friable, slightly sticky and slightly plastic; few fine and medium roots; few very fine and common fine irregular pores; 65 percent gravel of which 40 percent is broken pan fragments; 10 percent thin secondary calcium carbonate concretions around rock fragments and secondary silica and calcium carbonate pendants on the bottom of rock fragments; calcium carbonate equivalent is 14 percent; violently effervescent; strongly alkaline (pH 8.6); very abrupt wavy boundary. (5 to 18 cm thick)

Bqkm--20 to 89 cm; white (10YR 8/1) cemented material, very pale brown (10YR 7/3) moist; strong thick platy structure; very rigid, indurated (2 to 5 mm thick) laminar caps alternating with moderately and strongly cemented material, cemented by secondary silica and calcium carbonate; few very fine and fine roots mostly matted on laminar caps; few very fine and fine interstitial pores; 30 percent extremely gravelly sandy loam between cemented layers; violently effervescent; strongly alkaline (pH 8.9); gradual wavy boundary. (50 to 100 cm thick)

Bkq--89 to 150 cm; light gray (10YR 7/2) extremely gravelly coarse sand, brown (10YR 5/3) moist; single grain; loose, nonsticky and nonplastic; few very fine irregular pores; 65 percent gravel; many (40 percent) discontinuous lenses less than 8 cm thick that are weakly and moderately cemented by secondary calcium carbonate and silica with secondary calcium carbonate coats decreasing on gravel with depth; calcium carbonate equivalent is 5 percent; violently effervescent; very strongly alkaline (pH 9.3).

TYPE LOCATION: Lincoln County, Nevada; approximately 15 miles north of Hiko, 2.5 miles south southwest of White River Narrows, 1.25 miles east of state highway 318, and 50 feet south of two track road; about 200 feet north and 660 feet east of the southwest corner section 8, T.2 S., R. 62 E.; USGS White River Narrows 7.5 minute topographic quadrangle; latitude 37 degrees 47 minutes 4 seconds N and longitude 115 degrees 3 minutes 39 seconds W; WGS84 Decimal Degrees 37.7844444 latitude, -115.0608333 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist for short periods in winter and early spring and intermittently moist for 10 to 20 days cumulative from July through September due to convection storms; typic aridic soil moisture regime.
Mean annual soil temperature: 11 to 13 degrees C.
Depth to duripan: 10 to 25 cm.

Particle-size control section - Clay content: 8 to 18 percent.
Rock fragments: 35 to 60 percent, mostly gravel. Lithology of gravel is mainly broken pan fragments.

A horizon
Hue: 10YR or 7.5YR.
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 2 or 3, dry or moist.
Reaction: Moderate alkaline or strongly alkaline.
Calcium carbonate equivalent: 10 to 20 percent of the material less than 2 mm.

Bqk horizons
Hue: 10YR or 7.5YR.
Value: 7 or 8 dry, 5 through 7 moist.
Chroma: 1 through 3, dry or moist.
Texture: Extremely gravelly fine sandy loam and extremely gravelly sandy loam.
Reaction: Strongly alkaline or very strongly alkaline.
Calcium carbonate equivalent: 10 to 20 percent of the material less than 2 mm.

Bqkm horizon
Value: 7 or 8 dry, 7 or 8 moist.
Chroma: 1 through 3, dry or moist.
Cementation: Indurated laminar caps 1 to 10 millimeters thick and alternating layers of indurated or very strongly cemented material and moderately cemented or strongly cemented material are in most pedons.

Bkq horizon
Hue: 10YR or 7.5YR.
Value: 6 through 8 dry, 4 through 7 moist.
Chroma: 1 through 3 dry or moist.
Texture: Loamy coarse sand or coarse sand.
Clay content: 0 to 5 percent.
Rock fragments: 60 to 80 percent, mainly gravel.
Reaction: Strongly alkaline or very strongly alkaline.
Other features: 15 to 40 percent of the layer is discontinuous cemented layers less than 8 cm thick that are weakly and moderately cemented by secondary calcium carbonate and silica.

COMPETING SERIES: These are the Osobb, Osoll, Otomo, and Pahroc soils.

Osobb and Osoll soils have a duripan capping bedrock at 50 to 100 cm. Otomo soils are not moist for 10 to 20 days cumulative from July through September and have CaCO3 equivalents of less than 5 percent above the duripan. Pahroc soils have a duripan at a depth of 25 to 50 cm.

GEOGRAPHIC SETTING: Treadwell soils are on fan remnants and partial ballenas that have been dissected by intermittent drainage channels.. These soils formed in calcareous loess over alluvium derived from welded tuff and basalt. Slopes range from 4 to 30 percent. Elevations range from 1,295 to 1,955 meters. The mean annual temperature is 10 to 12 degrees C, mean annual precipitation is 150 to 200 mm and the frost-free period is 110 to 140 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chuckridge, Geer, Handpah, Malmesa, Nevoyer, and Penoyer series. Chuckridge soils have argillic horizons and 22 to 32 percent clay in the particle-size control section. Geer soils lack duripans and do not have any rock fragments in the particle-size control section. Handpah soils have duripans at 36 to 50 cm depth and 25 to 35 percent clay in the particle-size control section. Malmesa and Nevoyer soils have a duripan over lithic contact. Penoyer soils do not have a duripan and have a coarse-silty control section.

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

USE AND VEGETATION: Treadwell soils are used for livestock grazing and wildlife habitat. The potential native vegetation includes Indian ricegrass, galleta, spiny menodora and Nevada ephedra. This pedon is correlated to Ecological Site R029XY161NV, Shallow Cobbly Loam 8-10 P.Z.

DISTRIBUTION AND EXTENT: South central Nevada. They are not extensive. MLRA 29.

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

SERIES ESTABLISHED: Lincoln County, Nevada, North Part, 2006. The name is from a mine in the area.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A and part of Bqk horizons).
Duripan - The zone from 20 to 89 cm (Bqkm horizon).
Particle size control section - The zone from the surface to 20 cm (A and Bqk horizons).

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National Cooperative Soil Survey
U.S.A.