LOCATION FRAVAL                  NV+CA

Established Series
Rev. WED-JVC
03/2017

FRAVAL SERIES

The Fraval series consists of moderately deep, well drained soils that formed in residuum and colluvium derived from tuff and altered andesite. Fraval soils are on mountains. Slopes are 5 to 50 percent. The mean annual precipitation is about 560 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Ultic Argixerolls

TYPICAL PEDON: Fraval cobbly loam--forest land. (Colors are for dry soil unless otherwise noted.)

A--0 to 23 cm; dark grayish brown (10YR 4/2) cobbly loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; many very fine and fine interstitial pores; 10 percent gravel, 5 percent cobbles, and 3 percent stones; slightly acid (pH 6.2); clear smooth boundary. (18 to 36 cm thick)

Bt1--23 to 46 cm; brown (10YR 5/3) very gravelly loam, brown (10YR 4/3) moist; weak fine angular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine and many medium roots; many very fine, fine and medium tubular pores; common faint clay bridges between mineral grains and few faint clay films lining pores; 25 percent gravel and 10 percent cobbles; slightly acid (pH 6.2); gradual wavy boundary. (20 to 50 cm thick)

Bt2--46 to 69 cm; light yellowish brown (10YR 6/4) very cobbly loam, brown (10YR 4/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; many fine and medium roots; 30 percent cobbles and 10 percent gravel; few faint clay bridges between mineral grains; slightly acid (pH 6.2); gradual irregular boundary. (13 to 38 cm thick)

Cr--69 cm; highly weathered tuff.

TYPE LOCATION: Washoe County, Nevada; on the Toiyabe National Forest about 8 miles south-southwest of Reno; approximately 2,600 feet east and 200 feet north of the southwest corner of section 21, T. 18 N., R. 19 E.; USGS Mount Rose NE 7.5 minute topographic quadrangle; latitude 39 degrees 24 minutes 12.68 seconds N. and longitude 119 degrees 51 minutes 15.69 seconds W., WGS84 Decimal Degrees 39.4036111 latitude, -119.8544444 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in the moisture control section in winter and spring, dry in summer and fall for 80 to 100 consecutive days; Xeric moisture regime that borders on aridic.
Mean annual soil temperature - 6.7 to 8.5 degrees C.
Mollic epipedon thickness - 18 to 36 cm.
Depth to base of argillic horizon - 50 to 100 cm.
Depth to bedrock - 50 to 100 cm to a paralithic contact. The paralithic materials below the contact are soft, weathered tuff or hydrothermally altered andesite.
Reaction - Moderately acid or slightly acid.
Base saturation - less than 75 percent by sum of cations method in a least one horizon between 25 centimeters and the paralithic contact.
Particle-size control section - Clay content: 20 to 35 percent; Rock fragments: 35 to 60 percent, mainly gravel and cobbles. Lithology of fragments are volcanic rocks such as tuff or andesite.

A horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 2 to 4 percent.

Bt horizons
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Very gravelly loam, very gravelly clay loam, or very cobbly loam.
Clay content: 20 to 35 percent.
Other features: Some pedons have 5 to 15 percent pararock fragments.

COMPETING SERIES: These are the Bullville, Brassey, Durst, Fergie, Henhoit, Little Wood, Morningstar, Mulshoe, Sapkin, and Sattley series.

Bullville soils are dominated by fine gravel in the particle-size control section and have paralithic materials that are weathered granitic rock in the series control section. Brassey, Henhoit, Little Wood, and Morningstar soils are very deep. Durst and Sapkin soils are moderately deep to lithic contacts. Fergie and Sattley soils are deep to lithic contacts. Mulshoe soils are dominated by stones in the particle-size control section and have paralithic materials that are weathered basalt in the series control section.

GEOGRAPHIC SETTING: Fraval soils are on mountains. They typically occur on footslope or backslope positions. These soils formed in residuum and colluvium derived from tuff and altered andesite. Slopes are 5 to 50 percent. Elevations range from 1,707 to 2,591 meters. The climate is dry-subhumid with cold, moist winters and warm, dry summers. The mean annual precipitation is 400 to 760 mm. The mean annual temperature is 6 to 7 degrees C., the mean January temperature is about 0 degrees C., and the mean July temperature is about 18 degrees C. The frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Booford, Hirschdale, and Jumbo soils. Booford soils are fine textured and have higher base saturation. Hirschdale soils are fine textured and have ochric epipedons. Jumbo soils are deep to paralithic contacts and have thick mollic epipedons.

DRAINAGE AND SAURATED HYDRAULIC CONDUCTIVITY: Well drained; moderate permeability; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Fraval soils are used primarily for wildlife habitat and for watershed. Some areas are used for timber production. The vegetation is principally a forest canopy of Jeffrey pine with an understory of snowberry, manzanita, pinemat manzanita, and grasses. Mountain big sagebrush, antelope bitterbrush, and curlleaf mountainmahogany dominate in burned-over or harvested areas, especially on south-facing slopes.

DISTRIBUTION AND EXTENT: Western Nevada and northeastern California. These soils are moderately extensive. The series concept and main acreage is in MLRA 26, while other acreage occurs in MLRA 22A.

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

SERIES ESTABLISHED: Washoe County, Nevada, South Part, 1980.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 23 cm (A horizon).
Argillic horizon - The zone from 23 to 69 cm (Bt1 and Bt2 horizons).
Paralithic contact - The boundary at 69 cm to underlying soft, weathered bedrock (Cr layer).
Particle-size control section - The zone from 23 to 69 cm (Bt1 and Bt2 horizons).

---

National Cooperative Soil Survey
U.S.A.