LOCATION TUNNISON CA+NV

Established Series
Rev. KJO/JBF/TM/JVC
12/2013

TUNNISON SERIES

The Tunnison series consists of moderately deep, well drained soils that formed in colluvium over residuum derived from andesite or basalt. Tunnison soils are on plateaus. Slopes are 0 to 15 percent. The mean annual precipitation is about 280 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Very-fine, smectitic, mesic Aridic Haploxererts

TYPICAL PEDON: Tunnison very cobbly clay--on a planar, south-facing slope of 2 percent under low sagebrush and Thurber's needlegrass--rangeland. (Colors are for dry soil unless otherwise noted. When described on August 6, 1981, the soil was slightly moist between 38 and 79 cm, but dry elsewhere.)

A--0 to 3 cm; reddish brown (5YR 5/3) very cobbly clay, reddish brown (5YR 5/4) moist; strong fine and medium granular structure; slightly hard, very friable, very sticky and very plastic; common very fine roots; many very fine interstitial pores; 20 percent stones, 25 percent cobbles, and 10 percent gravel of hard, subrounded basalt; neutral (pH 7.2); clear wavy boundary. (3 to 8 cm thick)

Bw1--3 to 13 cm; reddish brown (5YR 5/3) clay, reddish brown (5YR 5/4) moist; strong coarse angular blocky structure; hard, very friable, very sticky and very plastic; common very fine, few fine and medium roots; many very fine interstitial pores; vertical cracks 10 to 30 mm wide and about 8 to 15 cm apart; neutral (pH 7.2); clear wavy boundary.

Bw2--13 to 38 cm; reddish brown (5YR 5/3) clay, reddish brown (5YR 5/4) moist; strong coarse and very coarse prismatic structure; very hard, very friable, very sticky and very plastic; few very fine and fine roots; common very fine tubular pores; vertical cracks 10 to 20 mm wide and about 8 to 15 cm apart; many (75 percent) pressure cutans on faces of peds; neutral (pH 7.1); clear wavy boundary.

Bss--38 to 69 cm; reddish brown (5YR 5/3) clay, reddish brown (5YR 5/4) moist; moderate coarse prismatic structure parting to moderate medium angular blocky; very hard, friable, very sticky and very plastic; few very fine, few fine and common medium roots; common very fine tubular pores; vertical cracks 10 to 20 mm wide and about 8 to 15 cm apart; wedge-shaped peds 1.2 to 2.5 cm across with surface tilting 30 degrees from the horizontal and with continuous intersecting slickensides; slightly alkaline (pH 7.6); clear wavy boundary. (Combined thickness of the Bw and Bss horizons is 46 to 79 cm)

BC--69 to 79 cm; reddish brown (5YR 5/4) clay, reddish brown (5YR 4/3) moist; strong fine and medium angular blocky structure; hard, very friable, very sticky and very plastic; few very fine roots; common very fine tubular pores; common distinct light reddish brown (5YR 6/4) pressure cutans on faces of peds, reddish brown (5YR 4/4) moist; slightly alkaline (pH 7.7); abrupt wavy boundary. (0 to 10 cm thick)

Cr--79 to 97 cm; reddish yellow (5YR 7/6) soft, weathered andesite, yellowish red (5YR 5/8) moist; weathered into medium and thick plates in upper 5 to 8 cm with secondary silica coats on bottoms of some plates; can be dug with a spade; clear wavy boundary. (10 to18 cm thick)

R--97 cm; hard, unweathered andesite.

TYPE LOCATION: Lassen County, California; about 10.8 miles southwest of Ravendale and 790 feet south of the borrow pit that is 1 mile east of Horse Lake and just north of the Ravendale road; approximately 1,850 feet south and 900 feet east of the northwest corner of section 1, T. 32 N., R. 13 E.; USGS West of Snowstorm Mtn. 7.5 minute topographic quadrangle; latitude 40 degrees 39 minutes 48 seconds N and longitude 120 degrees 28 minutes 07 seconds W; NAD 83, UTM Zone 10, 713984e, 4504466n.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section during winter and spring, dry in summer and fall; When dry, vertical cracks 0.5 to 8 cm wide and 5 to 28 cm apart extend from the surface to at least 56 cm or to bedrock. These cracks remain open from about June 1 through mid-December, about 200 days and are closed from January 1 to mid-April, more than 60 consecutive days; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 8 to 10 degrees C.
Depth to base of cambic horizon: 38 to 90 cm.
Depth to bedrock: 50 to 90 cm to a paralithic contact; The paralithic materials below the contact are weathered andesite or basalt. Hard, unweathered bedrock is usually within 100 cm.
Slickensides and other vertic features: Wedge-shaped peds tilted 30 to 60 degrees from the horizontal and intersecting slickensides occur at some depth between 25 cm from the soil surface and the bedrock contact.
Other features: Commonly, 35 to 60 percent rock fragments cover the soil surface, mostly stones and cobbles. Micro hummocks 8 or 8 cm high occur between rock fragments.

Particle-size control section - Clay content: 60 to 70 percent.

A horizon
Hue: 5YR or 7.5YR.
Value: 4 or 5 moist or dry.
Chroma: 2 through 4 dry, 3 or 4 moist.
Reaction: Neutral or slightly alkaline.

Bw and Bss horizons, and BC horizon (when present)
Hue: 5YR or 7.5YR.
Value: 4 or 5 moist or dry.
Chroma: 2 through 4 dry, 3 or 4 moist.
Clay content: 60 to 70 percent.
Reaction: Neutral or slightly alkaline.
Other features: Identifiable secondary carbonates occur at depths from 23 to 30 inches in some pedons.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Tunnison soils are on plateaus. They typically occur on depressions or summit positions. These soils formed in materials derived from andesite or basalt. Slopes are 0 to 15 percent. Elevations range from 1,405 to 1,942 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 230 to 330 mm. Annual snowfall is 250 to 500 mm. The mean annual temperature is 7 to 9 degrees C. The frost-free period is 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: This is the Devada soil. Devada soils are shallow to lithic contacts and have mollic epipedons and argillic horizons.

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

USE AND VEGETATION: Tunnison soils are used for rangeland and wildlife habitat. Vegetation is low sagebrush, rubber rabbitbrush, western wheatgrass, beardless wildrye, and Thurber's needlegrass.

DISTRIBUTION AND EXTENT: Northeastern California and northwestern Nevada. These soils are moderately extensive. MLRA 23.

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

SERIES ESTABLISHED: Washoe County (Central Part), Nevada, 1990.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A and Bw1 horizons and part of the Bw2 horizon).
Cambic horizon - The zone from 3 to 79 cm (Bw1, Bw2, Bss, and BC horizons).
Slickensides - The zone from 38 to 69 cm (Bss horizon).
Other vertic features - The zone from 3 to 69 cm (Bw1, Bw2, and Bss horizons).
Paralithic contact - The boundary at 79 cm to underlying soft, weathered bedrock (Cr layer).
Particle-size control section - The zone from 25 to 79 cm (Bss and BC horizons and part of the Bw2 horizon).

ADDITIONAL DATA: The typical pedon at the series type location has full characterization data by the Soil Survey Laboratory (SSL), Lincoln, NE, as soil survey sample number S81CA-035-006 (pedon # 81P0698).
User pedon ID: 02CA0352053.

National Cooperative Soil Survey
U.S.A.