LOCATION COELHO OR
Tentative Series
Rev. SCW/TDT
11/2010
COELHO SERIES
The Coelho series consists of very shallow, well drained soils formed in colluvium and residuum derived from basalt or welded tuff. Coelho are on basalt plateaus or benches. Slopes are 2 to 20 percent. The mean annual precipitation is about 40 centimeters (16 inches), and the mean annual temperature is about 10 degrees C. (50 degrees F.)
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Aridic Lithic Argixerolls
TYPICAL PEDON: Coelho very stony clay loam - rangeland, on a 2 percent slope at an elevation of 1,167 meters (3,830 feet). (When described on August 28, 2008, the soil was dry throughout. Colors are for moist soil unless otherwise noted.)
A--0 to 13 centimeters (0 to 5 inches) very dark grayish brown (10YR 3/2) very stony clay loam, grayish brown (10YR 5/2) dry; weak medium and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine and many very fine roots; few fine and common very fine tubular pores; 15 percent stones, 20 percent cobbles, and 15 percent gravel; neutral (pH 7.2); clear wavy boundary.
Bt--13 to 23 centimeters (5 to 9 inches) very dark grayish brown (10YR 3/2) very cobbly clay, dark grayish brown (10YR 4/2) dry; weak fine and medium subangular blocky structure; very hard, very firm, very sticky and very plastic; few fine and common very fine roots; few very fine tubular pores; few faint clay films on ped faces; 10 percent stones, 20 percent cobbles, and 20 percent gravel; neutral (pH 7.3); abrupt wavy boundary.
2R--23 centimeters (9 inches); basalt.
TYPE LOCATION: Grant County, Oregon, about 4.5 miles northwest of the Ritter junction; 300 feet north and 600 feet east of the southwest corner of section 21, T. 8 S., R. 30 E. (Latitude 44 degrees, 51 minutes, 10 seconds north and Longitude 119 degrees, 07 minutes, and 45 seconds west on the Flowers Gulch USGS quad)
RANGE IN CHARACTERISTICS: The soil is dry in all parts for more than to three-fourths of the time when the soil temperature is 5 degrees C. (41 degrees F.) or more. The mean annual soil temperature is 10 to 12 degrees C. (50 to 54 degrees F.) Depth to the lithic contact is 10 to 25 centimeters (4 to 10 inches). The particle size control section averages 35 to 45 percent clay and 35 to 50 percent coarse fragments. Hue throughout the profile is 10YR or 7.5YR.
The A horizon has value of 2 or 3 moist, and chroma of 2 or 3 dry. It has 0 to 15 percent stones, 20 to 35 percent cobbles, and 15 to 25 percent gravel. It is clay loam and has 27 to 35 percent clay.
The Bt horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. This horizon has moderate subangular blocky or angular blocky structure. It has 40 to 50 percent clay with 0 to 15 percent stones, 15 to 30 percent cobbles, and 10 to 20 percent gravel.
COMPETING SERIES: These are the
Camaspatch,
Flatron,
Gwinly,
Laufer,
Longcreek,
Loomer,
Lorella,
Pioche,
Radec,
Ruckles,
Vantage, and
Waterbury series. All these series are greater than 10 inches to bedrock.
GEOGRAPHIC SETTING: Coelho soils are on plateaus or benches and have slopes of 2 to 20 percent. These soils occur on ridgetops and intermounds of mound-intermound complexes. These soils formed in colluvium and residuum from basalt or tuff. Elevations are 762 to 1219 meters (2,500 to 4,000 feet). The climate is characterized by cool, moist winters and hot, dry summers. The mean annual precipitation is 254 to 406 millimeters (10 to 16 inches) and the mean annual temperature is 8.9 to 11.1 degrees C. (48 to 52 degrees F). The frost-free period is 110 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Canest,
Devnot, and
Elderflat series. Canest soils are frigid and are found at higher elevations. Devnot soils are clayey, shallow, and are on mounds. Coelho and Devnot soils are found in complex on mound-intermound areas. Elderflat soils are moderately deep to a lithic contact, clayey, and are found in broad, gently sloping swales or concave topography between areas of mound-intermounds.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. Potential native vegetation is Sandberg bluegrass, one-spike oatgrass, and serrate leaf balsomroot.
DISTRIBUTION AND EXTENT: East-central, Oregon, MLRA B-9. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Grant County, Oregon, 2008. The name is from Coelho Ranch located along Pass Creek north of the town of Long Creek.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon from 0 to 23 centimeters (0 to 9 inches)
Argillic horizon - from 13 to 23 centimeters (5 to 9 inches)
Lithic contact - 23 centimeters (9 inches)
Particle size control section - from surface to 23 centimeters (9 inches)
Aridic moisture regime
The ecological site at the type location for the Coelho series is R009XY025OR, Very Shallow 14-18 PZ
National Cooperative Soil Survey
U.S.A.