LOCATION ALOMAX                  CA

Established Series
Rev. JAG-SJB-JVC-JBF
07/2011

ALOMAX SERIES

The Alomax series consists of shallow, well drained soils that formed in colluvium derived from andesite or basalt. Alomax soils are on mountains. Slopes are 30 to 50 percent. The mean annual precipitation is about 360 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Aridic Lithic Haploxerolls

TYPICAL PEDON: Alomax very stony sandy loam--on a west-facing slope of 30 percent under mountain big sagebrush and bluebunch wheatgrass at about 6,400 feet elevation--rangeland. (Colors are for dry soil unless otherwise noted. When described on September 27, 1977, the soil was dry throughout.).

A1--0 to 8 cm; dark grayish brown (10YR 4/2) very stony sandy loam, very dark brown (10YR 2/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine roots; many very fine and fine interstitial pores; 30 percent stones, 10 percent cobbles, and 10 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (5 to 13 cm thick)

A2--8 to 38 cm; grayish brown (10YR 5/2) extremely stony sandy loam, very dark brown (10YR 2/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; many very fine and fine roots; many very fine and fine interstitial pores; 20 percent stones, 20 percent cobbles, and 30 percent gravel; slightly acid (pH 6.5); abrupt wavy boundary. (20 to 38 cm thick)

R--38 cm; hard fractured basalt.

TYPE LOCATION: Lassen County, California; in the Skedaddle Mountains about one mile northwest of Hot Springs Peak; found by going 7.2 miles east of Big Mud Flat on the Smoke Creek Ranch Road to the first southbound road at Bull Flat, then continue south past Bull Spring to Jenkins Spring, then 3.4 miles south on a jeep trail along Pea Creek and 1,000 feet up the slope east of this trail; about 2,220 feet north and 725 feet east of the southwest corner of section 12, T. 29 N., R. 16 E.; USGS Little Mud Flat 7.5 minute topographic quadrangle; latitude 40 degrees 23 minutes 16 seconds N and longitude 120 degrees 07 minutes 54 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry in summer and fall; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Depth to bedrock : 25 to 50 cm to a lithic contact.
Reaction: Slightly acid or neutral.
Other features: Rock fragments on the soil surface, mostly cobbles and stones, range from 35 to 70 percent and average about 50 percent.

Particle-size control section - Clay content: 10 to 15 percent.
Rock fragments: Averages 40 to 70 percent, mainly stones. Lithology of fragments are volcanic rocks such as andesite or basalt.

A1 horizon
Hue: 7.5YR or 10YR, dry
Value: 4or 5 dry, 2or 3 moist.
Chroma: 2 or 3.
Organic matter content: 1 or 2 percent.

A2 horizon
Hue: 7.5YR or 10YR, dry
Value: 4or 5 dry, 2or 3 moist.
Chroma: 2 or 3.
Texture: Very stony sandy loam, very cobbly sandy loam, or extremely stony sandy loam.
Organic matter content: 1 or 2 percent.

COMPETING SERIES: This is the Gando series. Gando soils have a Bk horizon with secondary carbonates.

GEOGRAPHIC SETTING: Alomax soils are on mountains. They typically occur on backslope positions. These soils formed in colluvium derived from andesite or basalt. Areas of rock outcrop, stones, and cobbles are common and occupy up to 30 percent of the surface. Slopes are 30 to 50 percent. Elevations range from 1,680 to 2,230. The mean annual precipitation is 300 to 400 mm including 90 to 100 cm of annual snowfall. The mean annual temperature is 7 to 8 degrees C. The frost-free period is 60 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Devada, Glean, and Longcreek soils. Devada and Longcreek soils have argillic horizons and a mesic temperature regime. Glean soils are deep to lithic contacts and have thick mollic epipedons.

DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; moderately rapid permeability.

USE AND VEGETATION: Alomax soils are used for rangeland and wildlife habitat. The vegetation is bluebunch wheatgrass, Idaho fescue, and mountain big sagebrush.

DISTRIBUTION AND EXTENT: Northeastern California. These soils are not extensive with about 4,400 acres of the series mapped to date. MLRA 23.

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

SERIES ESTABLISHED: Lassen County (Susanville Area Soil Survey), California, 2000.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 38 cm (A1 and A2 horizons).
Lithic contact - The boundary at 38 cm to underlying hard, unweathered bedrock (R layer).
Particle-size control section - The zone from 25 cm to 38 cm ( part of the A2 horizon).

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

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National Cooperative Soil Survey
U.S.A.