LOCATION COWLAKE ORTentative Series
TAXONOMIC CLASS: Ashy-skeletal over loamy-skeletal, glassy over mixed, superactive, mesic Lithic Xeric Haplargids
TYPICAL PEDON: Cowlake very cobbly ashy loam, rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partly covered by 30 percent gravel, 10 percent cobbles, and 5 percent stones.
A--0 to 8 cm; pale brown (10YR 6/3) very cobbly ashy loam, very dark grayish brown (10YR 3/2) moist; weak medium platy structure; slightly hard, friable, nonsticky, nonplastic; common fine and very fine roots; common fine and medium vesicular pores; 20 percent gravel, 10 percent cobbles, and 5 percent stones; slightly alkaline (pH 7.6); clear wavy boundary. (5 to 12 cm thick)
AB--8 to 22 cm; pale brown (10YR 6/3) cobbly ashy loam, very dark grayish brown (10YR 3/2) moist; weak thin and medium platy structure; slightly hard, friable, nonsticky, nonplastic; common fine and very fine roots; common fine and very fine tubular pores; 20 percent cobbles and 10 percent stones; slightly alkaline (pH 7.6); clear wavy boundary. (11 to 14 cm thick)
Bt--22 to 30 cm; brown (10YR 4/3) very gravelly ashy clay loam, dark grayish brown (10YR 4/2) moist; weak fine and medium subangular blocky structure; moderately hard, firm, slightly sticky, slightly plastic; common fine and very fine roots; common fine and very fine tubular pores; 5 percent faint clay films on all faces of peds; 30 percent gravel and 5 percent cobbles and 5 percent stones; slightly alkaline (pH 7.6); clear wavy boundary. (6 to 23 cm thick)
R--30 cm; bedrock; indurated rhyolite.
TYPE LOCATION: Malheur County, Oregon; approximately 11 miles northwest of Jordan Valley; UTM 478542 easting, 4763930 northing, zone 11, NAD83 on the USGS Cow Lakes 7.5 minute quadrangle, latitude 43 degrees 1 minute 40.00 seconds north and longitude 117 degrees 15 minutes 48.00 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 surface is wet in April due to snowmelt; aridic moisture regime that borders on xeric.
Soil temperature - Mean annual temperature is 8 to 9 degrees C.
Depth to Bedrock - 20 to 33 cm.
Control section - Clay content - 20 to 30 percent.
Rock fragments - 35 to 50 percent.
A horizon -
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3 dry or moist.
Reaction: neutral to slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 30 to 50 percent of the 0.02 to 2 mm fraction.
AB horizon -
Value: 3 or 4 moist.
Chroma: 2 or 3 moist or dry.
Clay content: 18 to 25 percent.
Rock fragments: Averages 20 to 40 percent, mainly cobbles and stones.
Reaction: Neutral to slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 20 to 40 percent of the 0.02 to 2 mm fraction.
Bt horizon -
Value: 4 to 6 dry, 3 to 5 moist.
Chroma: 2 to 4 dry or moist.
Texture: Ashy loam, ashy clay loam.
Clay content: 18 to 35 percent.
Rock fragments: Averages 35 to 50 percent, mainly gravel and cobbles.
Reaction: Neutral to slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 5 to 30 percent of the 0.02 to 2 mm fraction.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Cowlake soils are on lava plateaus. These soils formed in mixed volcanic ash and loess over residuum from basalt and rhyolite. Slopes are 2 to 15 percent. Elevations are 1,370 to 1,490 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 200 to 330 mm; mean annual temperature is 7 to 8 degrees C, and the frost-free period is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Suncold and Bogusrim soils. Suncold and Bogusrim soils have duripans between 50 and 100 cm.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained, saturated in the upper part for two weeks or more in spring due to snowmelt, medium runoff, moderate and moderately slow permeability, and moderately high saturated hydraulic conductivity.
USE AND VEGETATION: Rangeland and wildlife habitat. The present vegetation is mainly stiff sagebrush and Sandberg's bluegrass.
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.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 22 cm (A and AB horizons).
Argillic horizon - The zone from about 22 cm to 30 cm (Bt horizon).
Ashy textures - Volcanic glass is 30 to 50 percent of the 0.02 to 2 mm fraction in the zone from 0 to 22 cm (A and AB horizons). Volcanic glass is 5 to 30 percent of the 0.02 to 2 mm fraction in the zone from 22 to 30 cm (Bt horizons).
Particle-size control section - The zone from 0 to 30 cm (A, AB and Bt horizons).