LOCATION DERALLO                 OR

Established Series
Rev. JSC-MPK-JVC-JBF
02/2011

DERALLO SERIES

The Derallo series consists of deep, well drained soils that formed in volcanic ash and colluvium over residuum derived from rhyolite. Derallo soils are on hills and mountains. Slopes are 15 to 60 percent. The mean annual precipitation is about 300 mm and the mean annual temperature is about 6 degrees C.

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

TYPICAL PEDON: Derallo extremely cobbly ashy fine sandy loam--on hill sloping 29 percent to the south at an elevation of 1,629 meters--rangeland. (Colors are for dry soil unless otherwise noted. When described on September 16, 2002 the soil was dry throughout.) The soil surface is partially covered with 30 percent gravel, 30 percent cobbles, 5 percent stones, and 1 percent boulders.

A1--0 to 3 cm; grayish brown (10YR 5/2) extremely cobbly ashy fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium granular structure; soft, very friable, slightly sticky and nonplastic; few very fine roots; many very fine interstitial pores; 30 percent gravel, 30 percent cobbles, and 5 percent stones; slightly acid (pH 6.4); abrupt smooth boundary. (3 to 10 cm thick)

A2--3 to 10 cm; grayish brown (10YR 5/2) extremely cobbly ashy loam, very dark grayish brown (10YR 3/2) moist; moderate coarse and medium granular structure; soft, friable, slightly sticky and slightly plastic; common very fine, common fine, and common medium roots; many very fine interstitial pores; 40 percent gravel, 30 percent cobbles, and 5 percent stones; slightly acid (pH 6.5); clear smooth boundary. (8 to 25 cm thick)

AB--10 to 30 cm; grayish brown (10YR 5/2) extremely gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; moderate medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, common fine, and common medium roots; many very fine interstitial and common very fine tubular pores; 50 percent gravel, 20 percent cobbles, and 5 percent stones; neutral (pH 6.9); gradual smooth boundary. (0 to 20 cm thick)

Bt1--30 to 48 cm; brown (10YR 5/3) extremely gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; moderate medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, common fine, and common medium roots; common very fine tubular and common very fine interstitial pores; 55 percent gravel and 20 percent cobbles; few faint clay bridges between sand grains; neutral (pH 7.1); clear smooth boundary. (13 to 25 cm thick)

Bt2--48 to 58 cm; brown (10YR 5/3) extremely gravelly ashy loam, dark brown (10YR 3/3) moist; strong fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine, common fine, and common medium roots; many very fine and few fine tubular pores; 30 percent fine gravel, 15 percent medium gravel, and 20 percent cobbles; few distinct clay films on faces of peds and lining pores, common faint clay bridges between sand grains; neutral (pH 7.1); clear smooth boundary. (0 to 13 cm thick)

Bt3--58 to 91 cm; brown (10YR 5/3) very gravelly ashy clay loam, brown (10YR 4/3) moist; strong fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and few fine roots; many very fine and few fine tubular pores; 15 percent fine gravel, 25 percent medium gravel, and 15 percent cobbles; common distinct clay films on faces of peds and lining pores; slightly alkaline (pH 7.4); gradual smooth boundary. (0 to 33 cm thick)

Bt4--91 to 104 cm; pale brown (10YR 6/3) very gravelly ashy fine [RL1]sandy loam, brown (10YR 4/3) moist; strong fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and few fine roots; common very fine tubular pores; 35 percent gravel and 10 percent cobbles; common faint clay films on faces of peds and lining pores; slightly alkaline (pH 7.5); clear wavy boundary. (0 to 13 cm thick)

Cr--104 to 130 cm; weathered glassy rhyolite (fibrous obsidian).

TYPE LOCATION: Lake County, Oregon; in the Glass Buttes about 0.25 miles southwest of Cabin Spring; approximately 1,600 feet north and 1,400 feet west of the southeast corner of section 34, T. 23 S., R. 22 E.; USGS Glass Butte 7.5 minute topographic quadrangle; latitude 43 degrees 31 minutes 53 seconds N and longitude 120 degrees 03 minutes 42 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: 6 to 7 degrees C.
Mollic epipedon thickness: 25 to 60 cm; includes the Bt1 and Bt2 horizons in some pedons.
Depth to base of argillic horizon: 100 to 150 cm.
Depth to bedrock: 100 to 150 cm to a paralithic contact.

Particle-size control section - Clay content: 22 to 32 percent;
Rock fragments: 40 to 60 percent, mainly gravel. Lithology of fragments are volcanic rocks such as rhyolite, rhyodacite, and obsidian (a glassy rhyolite).
Volcanic glass content - 30 to 80 percent in coarse silt through fine sand fractions with more glass concentrated in the fine sand fraction.

A and AB horizons
Chroma: 2 or 3, dry or moist.
Reaction: Slightly acid or neutral.
Organic matter content: 2 to 4 percent.

Bt horizons
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Texture: Extremely gravelly ashy loam, very gravelly ashy clay loam, very gravelly ashy sandy clay loam, or very cobbly ashy sandy clay loam.
Reaction: Neutral or slightly alkaline.
Organic matter content: 1 to 3 percent in the Bt1 and Bt2 horizons.
Other features: Some pedons have thin subhorizons (Bt4) of very gravelly ashy fine sandy loam below the particle-size control section.

COMPETING SERIES: These are the Cabinspring, Cagas, Glassbutte, Jacksplace, Roughridge, and Slockey series.

Cabinspring, Jacksplace, and Slockey soils are moderately deep to lithic contacts. Cagas soils are moderately deep to paralithic contacts. Glassbutte and Roughridge soils are very deep and have subhorizons with identifiable secondary carbonates.

GEOGRAPHIC SETTING: Derallo soils are on hills and mountains. They typically occur on backslope positions. These soils formed in volcanic ash and colluvium over residuum derived from volcanic rocks such as rhyolite, rhyodacite, and obsidian. Slopes are 15 to 60 percent. Elevations range from 1,355 to 1,925 meters. The climate is semiarid and characterized by cool, moist winters and warm, dry summers. The mean annual precipitation is 250 to 360 mm, the mean annual temperature is 4 to 6 degrees C, and the frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Cabinspring and Jacksplace soils and the Glencabin soil. Glencabin soils are ashy-skeletal, moderately deep to lithic contacts, and have cambic horizons.

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

USE AND VEGETATION: Derallo soils are used for livestock grazing and wildlife habitat. The historic plant community is western juniper, mountain big sagebrush, basin big sagebrush, bluebunch wheatgrass, and Idaho fescue.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are not extensive with about 2,900 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. The series was proposed as part of the Prineville District Area, BLM Brothers soil survey, Lake County, Oregon, 1980.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 58 cm (A1, A2, AB, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 30 to 104 cm (Bt1, Bt2, Bt3, and Bt4 horizons).
Vitrandic intergrade feature - The zone from the soil surface to 76 cm (A1, A2, AB, Bt1, and Bt2 horizons and part of the Bt3 horizon).
Paralithic contact - The boundary at 104 cm to underlying weathered bedrock (Cr layer).
Particle-size control section and ashy-skeletal substitute class with glassy mineralogy - The zone from 30 to 82 cm (Bt1 and Bt2 horizons and part of the Bt3 horizon).

A revision in January 2003 moved the type location to a more representative area within Lake County and revised the series concept.

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-037-003 (pedon # 03N0330). 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.