LOCATION GIRANCH                 OR

Established Series
Rev. CWL-MPK-JVC-JBF
03/2011

GIRANCH SERIES

The Giranch series consists of moderately deep to a duripan, well drained soils that formed in volcanic ash and alluvium derived from volcanic rocks. Giranch soils are on fan remnants. Slopes are 2 to 20 percent. The mean annual precipitation is about 300 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy, frigid Vitritorrandic Durixerolls

TYPICAL PEDON: Giranch gravelly ashy loam--on a fan remnant sloping 6 percent to the northwest at an elevation of 1,445 meters--rangeland. (Colors are for dry soil unless otherwise noted. When described on October 17, 2002 the soil was dry throughout.)

A1--0 to 10 cm; grayish brown (10YR 5/2) gravelly ashy loam, very dark grayish brown (10YR 3/2); weak coarse and medium granular structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine irregular pores; 15 percent gravel and 5 percent cobbles; neutral (pH 7.0); clear smooth boundary. (5 to 10 cm thick).

A2--10 to 28 cm; grayish brown (10YR 5/2) gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; moderate coarse and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine, common fine, and common medium roots; many very fine irregular pores; 20 percent gravel and 5 percent cobbles; neutral (pH 7.0); abrupt wavy boundary. (13 to 23 cm thick).

Bt1--28 to 58 cm; brown (7.5YR 4/4) very gravelly ashy sandy clay loam, dark brown (7.5YR 3/3) moist; strong fine angular blocky structure; hard, very firm, very sticky and very plastic; common very fine, common fine, and common medium roots; common very fine tubular pores; 35 percent gravel, 15 percent cobbles, and 5 percent stones; many distinct clay films on faces of peds; dark grayish brown (10YR 4/2) organic coats on faces of peds in upper 8 cm of horizon; neutral (pH 7.0); gradual smooth boundary. (10 to 30 cm thick).

Bt2--58 to 74 cm; brown (7.5YR 4/3) gravelly clay, brown (7.5YR 4/3) moist; strong fine prismatic structure parting to strong fine angular blocky; hard, very firm, very sticky and very plastic; common very fine, common fine, and common medium roots; common very fine tubular pores; 20 percent gravel and 10 percent cobbles; many distinct clay films on faces of peds; neutral (pH 7.2); clear smooth boundary. (10 to 15 cm thick)

Btq--74 to 84 cm; yellowish brown (10YR 5/4) clay loam, dark yellowish brown (10YR 4/4) moist; strong medium and thick platy structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; many very fine irregular pores; 10 percent gravel; many distinct brown (10YR 4/3) dry, clay films on faces of peds; many distinct silt coats on faces of peds; about 25 percent of matrix is very weakly cemented by opaline silica; neutral (pH 7.3); clear smooth boundary. (0 to 10 cm thick)

2Bqkm--84 to 152 cm; light yellowish brown (10YR 6/4) and brown (10YR 4/3) cemented material, yellowish brown (10YR 5/4) and dark brown (10YR 3/3) moist; moderate very thick platy structure; extremely hard; very strongly cemented by secondary silica; common 1 to 2 mm. thick horizontal opaline silica coats on the tops of peds; secondary carbonates segregated as few fine filaments in the matrix; slightly effervescent in spots.

TYPE LOCATION: Lake County, Oregon; north of the Glass Buttes about one mile northwest of Chesebro Spring; approximately 1,400 feet south and 700 feet east of the northwest corner of section 14, T. 23 S., R. 22 E.; USGS Glass Butte 7.5 minute topographic quadrangle; latitude 43 degrees 34 minutes 54.1 seconds N and longitude 120 degrees 03 minutes 9.5 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry in summer and fall; aridic moisture regime bordering on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 25 to 58 cm; includes the Bt1 horizon in some pedons.
Depth to base of argillic horizon: 56 to 90 cm.
Depth to duripan: 56 to 90 cm.
Depth to bedrock: More than 200 cm.

Particle-size control section - Clay content: Averages 35 to 50 percent.
Rock fragments: Averages 35 to 60 percent. Lithology of fragments are volcanic rocks such as obsidian, rhyolite, or tuff.

A horizons
Chroma: 2 or 3, dry or moist.
Volcanic glass content: 30 to 60 percent in coarse silt through fine sand fractions.
Organic matter content: 2 to 4 percent.

Bt1 horizon
Hue: 7.5YR or 10YR.
Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Texture: Very gravelly ashy sandy clay loam or very stony ashy clay loam.
Clay content: 30 to 40 percent.
Volcanic glass content: 30 to 60 percent in coarse silt through fine sand fractions.
Reaction: Neutral or slightly alkaline.
Organic matter content: 1 to 3 percent.

Bt2 horizon
Hue: 7.5YR or 10YR.
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Texture: Gravelly clay or very stony clay.
Clay content: 40 to 55 percent.
Reaction: Neutral or slightly alkaline.

Btq horizon (when present)
Value: 5 or 6 dry.
Chroma: 3 or 4, dry or moist.
Clay content: 27 to 40 percent.
Reaction: Neutral or slightly alkaline.
Other features: Some pedons have a Bk horizon above the duripan.
Bqkm horizon
Cementation: Strongly cemented through indurated.

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

GEOGRAPHIC SETTING: Giranch soils are on fan remnants. They formed in volcanic ash mixed with alluvium derived from volcanic rocks. Slopes are 2 to 20 percent. Elevations range from 1,345 to 1,510 meters. The climate is semiarid with cold, moist winters and warm, dry summers. The mean annual precipitation is 280 to 360 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 60 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Meld and Moonbeam soils. Meld soils are ashy. Moonbeam soils are shallow to duripans and are on adjacent lava plateaus.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high surface runoff; slow permeability; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Giranch soils are used for livestock grazing. The vegetation is basin big sagebrush, mountain big sagebrush, Idaho fescue, Thurber's needlegrass, and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are not extensive with about 1,400 acres of the series mapped to date. MLRA 23.

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

SERIES ESTABLISHED: Lake County (Northern Part), Oregon, 2006.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 58 cm (A1, A2, and Bt1 horizons).
Argillic horizon - The zone from 28 to 84 cm (Bt1, Bt2, and Btq horizons).
Vitrandic intergrade feature - The zone from the soil surface to 58 cm (A1, A2, and Bt1 horizons).
Duripan and identifiable secondary carbonates - The zone from 84 to 152 cm (Bqkm horizon).
Ashy-skeletal substitute class with glassy mineralogy - The zone from 28 to 58 cm (Bt1 horizon).
Particle-size control section - The zone from 28 to 79 cm (Bt1 and Bt2 horizons and part of the Btq horizon).

ADDITIONAL DATA: The typical pedon at the series type location is reference sampled for the Soil Survey Laboratory (SSL), Lincoln, NE, as soil survey sample number S02OR-037-002 (pedon # 03N0329). Selected data including optical glass counts are available. Volcanic glass content has also been determined locally in the Reno MO by optical grain counts using a polarizing petrographic microscope.

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National Cooperative Soil Survey
U.S.A.