LOCATION YAWKOLA OREstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Pachic Palexerolls
TYPICAL PEDON: Yawkola very gravelly silt loam - on a 14 percent slope, woodland. (Colors are for moist soil unless otherwise noted.)
Oi--1 inch to 0; organic layer of needles and twigs.
A1--0 to 7 inches; very dark grayish brown (10YR 2/2) very gravelly silt loam, grayish brown (10YR 5/2) dry; moderate medium platy structure; slightly hard, friable, nonsticky and nonplastic; many very fine, fine, medium, and coarse roots; many very fine, fine, medium, and coarse irregular pores; 30 percent gravel and 15 percent cobbles; neutral (pH 6.8); clear smooth boundary. (4 to 8 inches thick)
A2--7 to 11 inches; very dark grayish brown (10YR 3/2) very gravelly silt loam, grayish brown (10YR 5/2) dry; moderate medium and fine subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; many very fine, fine, medium, and coarse roots; many very fine, fine, medium, and coarse irregular pores; 35 percent gravel and 15 percent cobbles; neutral (pH 6.8); abrupt smooth boundary. (3 to 5 inches thick)
2Bt1--11 to 30 inches; dark brown (10YR 3/3) very gravelly silty clay, brown (10YR 5/3) dry; strong coarse prismatic structure parting to moderate medium subangular blocky; extremely hard, extremely firm, sticky and plastic; many very fine, fine and common medium and coarse roots; many very fine, fine and common medium and coarse tubular pores; continuous prominent clay films on faces of peds and lining pores; 35 percent gravel and 15 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (13 to 20 inches thick)
2Bt2--30 to 40 inches; dark yellowish brown (10YR 3/4) extremely gravelly silty clay, yellowish brown (10YR 5/4) dry; moderate medium subangular blocky structure; very hard, very firm, sticky and plastic; common very fine and fine roots; common very fine and fine tubular pores; continuous prominent clay films on faces of peds and lining pores; common fine manganese stains; 45 percent gravel and 20 percent cobbles; slightly acid (pH 6.2); clear smooth boundary. (8 to 12 inches thick)
3Bt3--40 to 60 inches; dark yellowish brown (10YR 4/4) gravelly silt loam, light yellowish brown (10YR 6/4) dry; moderate medium and fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few very fine and fine roots; few very fine and fine tubular pores; common distinct clay films on faces of peds; 25 percent gravel; slightly acid (pH 6.2)
TYPE LOCATION: Wasco County, Oregon, about 200 feet west and 3000 feet north of the SE corner of section 24, T.6 S., R.11 E. (Latitude 45 degrees, 01 minutes, 54 seconds N, Longitude 121 degrees, 21 minutes, 31 seconds W) Warm Springs Indian Reservation.
RANGE OF CHARACTERISTICS: These soils are usually moist, but are dry in all parts of the moisture control section for 60 to 90 consecutive days within the four months that follow the summer solstice. The mean annual soil temperature is 47 to 51 degrees F. Depth to sedimentary bedrock is greater than 60 inches. The mollic epipedon is 20 to 30 inches thick and includes all or part of the argillic horizon. The particle-size control section averages 40 to 50 percent clay and 45 to 70 percent rock fragments.
The A horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 2 or 3 moist and dry. It has 10 to 20 percent clay and contains 25 to 40 percent gravel and 5 to 15 percent cobbles. It has an estimated 10 to 30 percent volcanic glass and 0.4 to 1.0 percent acid oxalate extractable aluminum plus one-half iron.
The 2Bt horizon has value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist and dry. It is silty clay or clay with 40 to 50 percent clay. It contains 35 to 50 percent gravel and 10 to 25 percent cobbles.
The 3Bt horizon has value of 4 or 5 moist, 5 or 6 dry and chroma of 3 or 4 moist and dry. It is silt loam or loam with 20 to 27 percent clay. It contains 20 to 30 percent gravel.
COMPETING SERIES: This is the Palerf (T) soil. Palerf soils are moderately deep to bedrock and have an aridic soil moisture regime.
GEOGRAPHIC SETTING: Yawkola soils are on gently sloping to very steep side slopes of mountains. The soil formed in residuum and colluvium derived dominantly from sedimentary rock with an influence of volcanic ash in the surface. Slopes are 2 to 55 percent. Elevations are 2600 to 3500 feet. The climate is characterized by cool and wet winters and hot and dry summers. The mean annual precipitation is 16 to 20 inches. The mean annual temperature is 45 to 49 degrees F. The frost-free period is 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boardflower, Bodell, Fawnspring, Jorn, Littlefawn and Logsprings soils. Boardflower soils are fine and are on adjacent north-facing side slopes. Bodell soils are loamy-skeletal, shallow to bedrock, and are on south-facing side slopes of mountains. Fawnspring soils are fine, deep to bedrock and are on adjacent north-facing side slopes. Jorn soils are fine, moderately deep to bedrock, and are on concave side slopes of mountains. Littlefawn soils are fine, moderately deep to bedrock, and are on adjacent north-facing side slopes. Logsprings soils are fine-loamy over clayey, moderately well drained, and are on concave areas of adjacent benches.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow.
USE AND VEGETATION: These soils are used for timber production, livestock grazing and wildlife habitat. The native vegetation is Ponderosa pine and Douglas fir with an understory of antelope bitterbrush, Idaho fescue, and Oregon white oak.
DISTRIBUTION AND EXTENT: North-central Oregon; MLRA 6. The soils of this series are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wasco County (Warm Springs Indian Reservation), Oregon, 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 30 inches (A1, A2, and 2Bt1 horizon).
Argillic horizon - The zone from 11 to 60 inches (2Bt1, 2Bt2, and 3Bt3 horizons).
Pale feature - argillic horizon with a clayey particle-size class and abrupt upper boundary (2Bt2 horizon) with an estimated increase of 20 percent clay absolute.
Vitrandic feature - The zone from 0 to 11 inches (A1 and A2 horizons)
Particle-size control section - The zone from 11 to 31 inches (2Bt1 horizon and upper 1 inch of 2Bt2 horizon).