LOCATION ASHFLAT CA+NV

Established Series
Rev. EWB-JVC-JBF
02/2017

ASHFLAT SERIES

The Ashflat series consists of very deep, well drained soils that formed in eolian volcanic ash and colluvium derived from volcanic rocks. Ashflat soils are on mountains. Slopes are 4 to 30 percent. The mean annual precipitation is about 380 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy Vitrandic Argicryolls

TYPICAL PEDON: Ashflat gravelly ashy sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 30 percent gravel and 5 percent cobbles.

A1--0 to 5 cm; grayish brown (10YR 5/2) gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium platy structure; soft, very friable, slightly sticky and nonplastic; many very fine roots; many very fine interstitial pores; 25 percent gravel; slightly acid (pH 6.4); clear wavy boundary. (3 to 15 cm thick)

A2--5 to 18 cm; brown (10YR 5/3) gravelly ashy sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; many very fine, fine and medium roots; many very fine interstitial and common very fine tubular pores; 30 percent gravel; slightly acid (pH 6.4);; clear wavy boundary. (0 to 13 cm thick)

Bt1--18 to 51 cm; brown (10YR 5/3) very gravelly ashy loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine, and medium roots; common very fine tubular and interstitial pores; few faint clay bridges between sand grains; 35 percent gravel; neutral (pH 6.6);; clear wavy boundary. (13 to 36 cm thick)

Bt2--51 to 84 cm; brown (7.5YR 5/2) very gravelly ashy loam, dark brown (7.5YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine and fine roots; common very fine tubular and interstitial pores; common faint clay bridges between sand grains; 30 percent gravel and 5 percent cobbles; neutral (pH 6.7);; clear wavy boundary. (30 to 50 cm thick)

Bt3--84 to 109 cm; brown (7.5YR 5/3) very gravelly ashy loam, dark brown (7.5YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; few very fine roots; common very fine tubular and interstitial pores; common faint clay bridges between sand grains; 40 percent gravel and 5 percent cobbles; neutral (pH 6.8);; clear wavy boundary. (25 to 50 cm thick)

Bt4--109 to 152 cm; brown (7.5YR 5/4) very gravelly ashy clay loam, dark brown (7.5YR 3/4) moist; weak coarse parting to moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few very fine roots; common very fine and fine tubular pores; common distinct clay films on faces of peds and lining pores; 50 percent gravel and 2 percent cobbles; neutral (pH 6.8).

TYPE LOCATION: Mono County, California; on the Toiyabe National Forest about 2.7 miles southeast of the Masonic Town site; approximately 900 feet north and 450 feet east of the southwest corner of section 25, T. 6 N., R. 26 E.; USGS Dome Hill 7.5 minute topographic quadrangle; latitude 38 degrees 20 minutes 4.0 seconds N and 119 degrees longitude 04 minutes 46 seconds W; WGS84 Decimal Degrees 38.3344444 latitude, -119.0794444 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section during late fall, winter, and spring; dry from July through early October for 75 to 90 consecutive days in the four months following the summer solstice; xeric moisture regime that borders on aridic.
Mean annual soil temperature: 7 to 8 degrees C.
Mean summer soil temperature: 12 to 15 degrees C.
Mollic epipedon thickness: 76 to 114 cm; includes the Bt1, Bt2, and Bt3 horizons.
Volcanic glass content: 35 to 60 percent in coarse silt through fine sand fractions.

Particle-size control section - Clay content: Averages 18 to 25 percent.
Rock fragments: Averages 35 to 50 percent, mainly gravel. Lithology of fragments is andesite.

A horizons
Chroma: 2 or 3 dry or moist.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.

Bt1, Bt2, and Bt3 horizons
Hue: 10YR or 7.5YR.
Chroma: 2 or 3, dry or moist.
Texture: Very gravelly ashy loam or very gravelly ashy sandy clay loam.
Clay content: 18 to 25 percent.
Rock fragments: 35 to 50 percent.
Organic matter content: 1 to 3 percent.

Bt4 horizon
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4 dry or moist.
Texture: Very gravelly ashy loam or very gravelly ashy clay loam.
Clay content: 25 to 35 percent.
Rock fragments: 35 to 60 percent.

COMPETING SERIES: These are the Beechcreek, Boulderfan, Cowbell, Euell, Fendersflat, Hardshoulder, Paynepeak, Pyropatti, Snag, and Tusune series.

Beechcreek, Fendersflat and Tusune soils are moderately deep. Boulderfan soils have endosaturation within 152 cm of the soil surface. Cowbell soils have more than 50 percent rock fragments in the particle-size control section and have mollic epipedons less than 75 cm thick. Euell, Paynepeak and Pyropatti soils are deep bedrock. Hardshoulder averages 12 to 18 percent clay in the control section. Snag soils have more than 50 percent rock fragments in the particle-size control section and are dominated by cobbles and stones.

GEOGRAPHIC SETTING: Ashflat soils are on mountains. They typically occur on toeslope, footslope and backslope positions. They formed in eolian volcanic ash and colluvium derived from volcanic rocks. The probable sources of the volcanic ash are the Mono Craters and Long Valley Caldera in eastern California. Slopes are 4 to 30 percent. Elevations range from 2,340 to 2,780 meters. The climate is continental with cold, moist winters and cool, dry summers. The mean annual precipitation is 350 to 400 mm, the mean annual temperature is 6 to 7 degrees C., and the frost-free period is 40 to 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Epvip and Domehill soils. Epvip soils are shallow to paralithic contacts and have a frigid temperature regime. Domehill soils are shallow to lithic contacts and have a frigid temperature regime.

DRAINAGE AND PERMEABILITY: Well drained; medium surface runoff; moderate permeability; moderately high or high saturated hydraulic conductivity.

USE AND VEGETATION: Ashflat soils are used for rangeland, recreation, watershed, and wildlife habitat. The native vegetation is mainly mountain big sagebrush, western needlegrass, sedge, and snowberry.

DISTRIBUTION AND EXTENT: Eastern California and western Nevada, in the western part of the Great Basin. These soils are not extensive with about 350 acres of the series mapped to date. MLRA 26.

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

SERIES ESTABLISHED: Mineral County Area, Nevada, 2005. The series was proposed in Mono County (Toiyabe National Forest Area), California, 2004.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 109 cm (A1, A2, Bt1, Bt2, and Bt3 horizons).
Argillic horizon - The zone from 18 to 152 cm (Bt1, Bt2, Bt3, and Bt4 horizons).
Vitrandic intergrade feature - The zone from the soil surface to 76 cm (A1, A2, and Bt1 horizons and part of the Bt2 horizon).
Particle-size control section and ashy substitute class with glassy mineralogy - The zone from 18 to 68 cm (Bt1 horizon and part of the Bt2 horizon).

ADDITIONAL DATA: Volcanic glass content determined locally by optical grain count with a polarizing petrographic microscope.
User Pedon ID: 2004CA051004.

National Cooperative Soil Survey
U.S.A.