LOCATION PINCHEY ORTentative Series
TAXONOMIC CLASS: Fine, smectitic, frigid Vitritorrandic Durixerolls
TYPICAL PEDON: Pinchey ashy silt loam, rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partly covered by 2 percent gravel.
A1--0 to 11 cm; brown (10YR 5/3) ashy silt loam, dark brown (10YR 3/3) moist; weak thin platy parting to weak fine granular structure; soft, very friable; nonsticky, nonplastic; many very fine and fine roots; common fine and very fine irregular pores; 1 percent fine gravel; slightly alkaline (pH 7.4); clear smooth boundary. (Combined thickness for A horizons is 25 to 40 cm)
A2--11 to 28 cm; brown (10YR 5/3) ashy silt loam, dark brown (10YR 3/3) moist; moderate thick platy parting to moderate subangular blocky; slightly hard, friable; slightly sticky, slightly plastic; common fine and very fine and few medium and coarse roots; many very fine and fine interstitial pores; 1 percent fine gravel; slightly alkaline (pH 7.4); clear smooth boundary.
Bt1--28 to 43 cm; brown (10YR 4/3) ashy silty clay loam, dark yellowish brown (10YR4/4) moist; weak medium prismatic parting to moderate fine subangular blocky; slightly hard, friable; moderately sticky, moderately plastic; common fine and very fine and few medium roots; many fine and very fine pores; 50 percent distinct clay films; 1 percent fine gravel; slightly alkaline (pH 7.4); clear smooth boundary. (10 to 25 cm thick)
Bt2--43 to 53 cm; brown (10YR 4/3) clay loam, dark yellowish brown (10YR 4/4) moist; weak medium prismatic parting to moderate fine subangular blocky; moderately hard, firm; moderately sticky, moderately plastic; common fine and very fine and few medium roots; many fine and very fine pores; 80 percent distinct clay films; 3 percent gravel; slightly alkaline (pH 7.4); clear smooth boundary. Combined thickness for Bt2 and Bt3 is 20 to 35 cm
Bt3--53 to 75 cm; brown (10YR 4/3) clay, brown (10YR 4/3) moist; moderate medium prismatic parting to moderate fine subangular blocky; moderately hard, firm; very sticky, very plastic; 90 percent prominent clay films; 12 percent gravel; slightly alkaline (pH 7.6); abrupt wavy boundary.
Bqm1--75 to 90 cm; pale brown (10YR 6/3), brown (10YR 4/3); cemented material; massive; rigid; very strongly cemented by secondary silica; slightly alkaline (pH 7.6); clear, gradual boundary. (5 to 25 cm thick)
Bqm2--90 cm; cemented material; massive; very rigid; indurated by secondary silica; slightly alkaline (pH 7.6).
TYPE LOCATION: Malheur County, Oregon; approximately 10 miles south of Jordan Valley, Oregon; UTM 487075 easting, UTM 4734911 northing, zone 11 NAD83 on the USGS Juniper Ridge 7.5 minute quadrangle, latitude 42 degrees 45 minutes 59.8 seconds north and longitude 117 degrees 9 minutes 28.14 seconds west, NAD83.
RANGE IN CHARACTERISTICS:
Soil moisture - The soil moisture control section is dry throughout in summer and fall and moist in winter and spring; the soil surface is wet in April due to snowmelt; Aridic moisture regime that borders on xeric.
Soil temperature - The mean annual soil temperature is 7 to 8 degrees C.
Depth to duripan - 50 to 90 cm.
Thickness of Mollic epipedon - 25 to 50 cm.
Control section - Clay content: 35 to 40 percent.
Rock fragments: 25 to 35 percent, mainly gravel and cobbles with basalt or tuff lithology.
A horizons -
Value: 4 to 5 dry, 2 to 3 moist.
Chroma: 2 or 3 moist or dry.
Reaction: Neutral to slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 30 to 50 percent of the 0.2 to 2 mm fraction.
AB horizons (when present) -
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3 moist or dry.
Clay content: 18 to 25 percent.
Texture: Loam or silt loam.
Rock fragments: 0 to 10 percent, mostly gravel.
Reaction: Neutral to slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 30 to 50 percent of the 0.2 to 2 mm fraction.
Bt1 horizon -
Value: 4 or 5 moist or dry.
Chroma: 3 or 4 moist or dry.
Clay content: 25 to 35 percent.
Texture: Silty clay loam, silt loam, or clay loam.
Rock fragments: 0 to 15 percent, mostly gravel.
Reaction: Neutral to slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 5 to 25 percent of the 0.2 to 2 mm fraction.
Bt2 and Bt3 horizons -
Value: 3 to 5 moist, 4 or 5 dry.
Chroma: 3 or 4 moist or dry.
Clay content: 35 to 50 percent.
Texture: Silty clay loam, clay loam, clay.
Rock fragments: 5 to 20 percent, gravel and cobbles.
Bkqm horizons -
Duripan cementation: very strongly cemented to indurated.
Other features: the upper part of the duripan is a 1 to 3 mm opal cap.
COMPETING SERIES: This is the Babala series. The Babala series is moderately deep to a duripan over basalt or tuff bedrock.
GEOGRAPHIC SETTING: Pinchey soils are on pediments and fan remnants. These soils formed in alluvium, loess, and ash. Slopes are 2 to 15 percent. Elevations are 1,430 to 1,585 meters. The climate is semiarid with cold, moist winters and warm, dry summers. The mean annual precipitation is 300 to 400 mm; mean annual temperature is 5 to 7 degrees C, and the frost-free period is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Salheur soils. Salheur soils are shallow to a duripan.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained, very slow permeability, and low saturated hydraulic conductivity.
USE AND VEGETATION: Rangeland and wildlife habitat. The present vegetation is mainly low sagebrush and Idaho fescue.
DISTRIBUTION AND EXTENT: Southeast Oregon; the soil is of small extent. MLRA 25.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES PROPOSED: Malheur County, Oregon, Southern Part, 2008.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon--The zone from the soil surface to about 28 cm (A horizon).
Argillic horizon--The zone from about 28 to 75 cm (Bt1, Bt2 and Bt3 horizons).
Duripan--The zone from about 75 to 90 cm.
Ashy textures - Volcanic glass is 30 to 50 percent of the 0.02 to 2 mm fraction in the zone from 0 to 28 cm (A1 and A2 horizons). Volcanic glass is 5 to 25 percent of the 0.02 to 2 mm fraction in the zone from 28 to 43 cm (Bt1 horizon).
Particle-size control section - the zone from 28 to 75 cm (Bt1, Bt2 and Bt3 horizons).