LOCATION DIABLOPEAK              OR

Established Series
Rev. CWL-JVC-JBF
12/2022

DIABLOPEAK SERIES

The Diablopeak series consists of shallow, well drained soils that formed in loess derived from mixed rocks over residuum derived from basalt. Diablopeak soils are on plateaus and hills. Slopes are 2 to 20 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Clayey, smectitic, frigid Lithic Natrargids

TYPICAL PEDON: Diablopeak very cobbly fine sandy loam--on a west facing slope of 5 percent at an elevation of 1,469 meters--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 5 cm; light brownish gray (10YR 6/2) very cobbly fine sandy loam, dark grayish brown (10YR 4/2) moist; weak thin platy structure parting to moderate medium granular; slightly hard, very friable, nonsticky and nonplastic; few very fine and few fine roots; common fine and common medium vesicular pores; 30 percent gravel, 20 percent cobbles, and 5 percent stones; moderately alkaline (pH 8.4); clear smooth boundary. (5 to 13 cm thick)

A2--5 to 15 cm; pale brown (10YR 6/3) cobbly fine sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure parting to moderate medium granular; soft, very friable, nonsticky and nonplastic; common very fine, common fine and few medium roots; common fine and common medium interstitial and tubular pores; 10 percent gravel and 10 percent cobbles; strongly alkaline (pH 8.6); abrupt smooth boundary. (0 to 15 cm thick)

E--15 to 18 cm; light gray (10YR 7/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine, common fine and few medium roots; common very fine and common fine tubular pores; 5 percent gravel and 5 percent cobbles; strongly alkaline (pH 8.6); abrupt smooth boundary. (3 to 8 cm thick)

2Btn--18 to 30 cm; light brown (7.5YR 6/3) clay, brown (7.5YR 4/3) moist; weak medium prismatic structure parting to strong medium angular blocky; very hard, very firm, moderately sticky and very plastic; few very fine, few fine and few medium roots; few very fine and few fine tubular pores; common distinct clay films on faces of peds; very strongly alkaline (pH 9.2); clear smooth boundary. (8 to 23 cm thick)

2Btnk--30 to 48 cm; pink (7.5YR 7/3) sandy clay, brown (7.5YR 5/3) moist; strong medium subangular blocky structure parting to moderate fine angular blocky; hard, firm, moderately sticky and moderately plastic; few very fine and few fine roots; few very fine and few fine tubular pores; common faint clay films on faces of peds; 10 percent gravel; secondary carbonates segregated in filaments, on faces of peds, and on bottoms of rock fragments; violently effervescent; very strongly alkaline (pH 9.6); abrupt smooth boundary. (10 to 23 cm thick)

2R--48 cm; hard, fractured unweathered basalt.

TYPE LOCATION: Lake County, Oregon; about 2.0 miles north of Diablo Peak, 0.5 mile northeast of Murphy's Waterhole, and 0.5 mile east of a jeep trail; approximately 600 feet south and 750 feet west of the northeast corner of section 11, T. 30 S., R. 18 E.; USGS Diablo Peak 7.5 minute topographic quadrangle; latitude 42 degrees 59 minutes 23 seconds N and longitude 120 degrees 32 minutes 49 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section in winter and spring, dry in summer and fall; typic aridic soil moisture regime.
Mean annual soil temperature: 7 to 8 degrees C.
Ochric epipedon thickness: 10 to 23 cm.
Abrupt textural change: An abrupt horizon boundary is normally present between the E horizon and the Btn horizon accompanied by an increase in clay content of more than 18 percent.
Depth to base of natric horizon: 36 to 50 cm.
Depth to bedrock: 30 to 50 cm to a lithic contact.

Particle-size control section - Clay content: averages 35 to 50 percent;
Rock fragments: Averages 0 to 15 percent, mainly gravel. Lithology of fragments is basalt.

A1 horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Reaction: Moderately alkaline through very strongly alkaline (up to pH 9.6).

A2 horizon
Value: 6 or 7 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Texture: Gravelly fine sandy loam, very gravelly fine sandy loam and cobbly fine sandy loam.
Clay content: 12 to 18 percent.
Rock fragments: 15 to 40 percent.
Reaction: Moderately alkaline or strongly alkaline.

E horizon
Hue: 7.5YR or 10 YR.
Value: 6 or 7 dry, 3 or 4 moist.
Chroma: 1 or 2, dry or moist.
Texture: Fine sandy loam, gravelly fine sandy loam, or cobbly fine sandy loam.
Clay content: 12 to 18 percent.
Rock fragments: 5 to 20 percent.
Reaction: Moderately alkaline or strongly alkaline.

2Btn horizon
Hue: 7.5YR or 10YR.
Value: 5 through 7 dry, 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Clay loam, clay, or cobbly clay loam.
Clay content: 35 to 55 percent.
Rock fragments: 0 to 20 percent.
Reaction: Strongly alkaline or very strongly alkaline (up to pH 9.6).
Salinity (EC): 4 to 8 mmhos/cm.
Sodicity (SAR): 13 to 30.

2Btnk horizon
Hue: 7.5YR or 10YR.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 3 or 4, dry and moist.
Texture: Sandy clay, clay loam, clay, or gravelly clay loam.
Clay content: 32 to 45 percent.
Rock fragments: 10 to 30 percent.
Reaction: Strongly alkaline or very strongly alkaline (up to pH 9.6)
Salinity (EC): 4 to 8 mmhos/cm.
Sodicity (SAR): 13 to 30.
Calcium carbonate equivalent: 5 to 10 percent.

2Bqnk horizon (when present)
Value: 6 or 7 dry, 4 to 6 moist.
Chroma: 3 or 4, dry and moist.
Texture: Clay loam, clay, or sandy clay.
Clay content: 30 to 45 percent.
Rock fragments: 0 to 15 percent.
Salinity (EC): 8 to 16 mmhos/cm.
Sodicity (SAR): 30 to 60.
Consistence: Firm and brittle moist.
Secondary silica: Occurs as few fine coats on bottom of rock fragments and faces of peds.
Cementation: Noncemented to discontinuously moderately cemented.
Identifiable secondary carbonates: Occurs as few fine coats on rock fragments and faces of peds.
Calcium carbonate equivalent: 5 to 10 percent.

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

GEOGRAPHIC SETTING: Diablopeak soils are on plateaus and hills. They typically occur on summit and shoulder positions. These soils formed in loess derived from mixed rocks over residuum derived from basalt. These soils occur downwind of a salty playa (Summer Lake) and frequently receive new deposits of loess high in sodium salts. Slopes are 2 to 20 percent. Elevations range from 1,435 to1,820 meters. The climate is arid with cold, moist winters and warm, dry summers. The mean annual precipitation is 200 to 250 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lonegrave, Locolake, and Yankeewell soils. Lonegrave soils are loamy-skeletal, moderately deep to lithic contacts, have cambic horizons, a mesic temperature regime, and an aridic moisture regime that borders on xeric. Locolake soils are loamy and shallow to indurated duripans overlying lithic contacts. Yankeewell soils are loamy, shallow to indurated duripans overlying lithic contacts, and have an aridic moisture regime that borders on xeric.

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

USE AND VEGETATION: Diablopeak soils are used for livestock grazing. The present vegetation is shadscale, bud sagebrush, black greasewood, spiny hopsage, and Indian ricegrass.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are moderately extensive. MLRA 23.

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

SERIES ESTABLISHED: Lake County (Northern Part), Oregon, 2006. The name is from a prominent peak in the area.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A1, A2, and E horizons).
Albic horizon - The zone from 15 to 18 cm (E horizon).
Abrupt textural change - The abrupt clay increase of more than 18 percent at 18 cm (between the E and 2Btn horizons).
Natric horizon - The zone from 18 to 48 cm (2Btn and 2Btnk horizons).
Lithic contact - The boundary at 48 cm to underlying hard bedrock (2R layer).
Particle-size control section - The zone from 18 to 48 cm (2Btn and 2Btnk horizons).

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National Cooperative Soil Survey
U.S.A.