LOCATION MOUND OREstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Pachic Ultic Argixerolls
TYPICAL PEDON: Mound stony loam--on a 35 percent slope at 5,820 feet elevation under ponderosa pine--forest land. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 2 inches; slightly decomposed plant material consisting of partially decomposed ponderosa pine needles, cones, twigs, and small limbs; abrupt wavy boundary. (0.5 to 2 inches thick)
A1--2 to 4 inches; dark brown (10YR 3/3) stony loam, very dark grayish brown (10YR 3/2) moist; weak fine and very fine granular structure; soft, very friable, nonsticky and nonplastic; many fine and very fine and common medium roots; 10 percent stones, 5 percent cobbles, and 5 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (2 to 4 inches thick)
A2--4 to 15 inches; dark brown (10YR 3/3) stony loam, very dark grayish brown (10YR 3/2) moist; weak medium and fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; 10 percent stones, 5 percent cobbles, and 5 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (5 to 12 inches thick)
2Bt1--15 to 20 inches; brown (10YR 4/3) very cobbly clay loam, dark brown (10YR 3/3) moist; moderate medium and fine subangular blocky structure; slightly hard, firm, slightly sticky and slightly plastic; common very fine, fine, and medium roots; many fine and very fine tubular pores; few faint clay films on faces of peds and lining pores; 5 percent stones, 25 percent cobbles, and 10 percent gravel; slightly acid (pH 6.4); clear smooth boundary.
2Bt2--20 to 31 inches; brown (10YR 4/3) very cobbly clay, dark brown (10YR 3/3) moist; moderate coarse and medium subangular structure; very hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; many very fine tubular pores; many prominent clay films on faces of peds and lining pores; 10 percent stones, 25 percent cobbles, and 10 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (Combined thickness of the 2Bt horizons is 16 to 43 inches.)
2C--31 to 44 inches; light brown (7.5YR 6/3) extremely paragravelly clay loam, brown (7.5YR 4/4) moist; massive, slightly hard, firm, moderately sticky and slightly plastic; few fine roots; few fine tubular pores; 5 percent cobbles and 5 percent gravel; 60 percent soft, weathered tuff paragravel fragments; slightly acid (pH 6.2); abrupt smooth boundary. (0 to 15 inches thick)
2Cr--44 to 47 inches; partially weathered, brown (7.5YR 4/4) tuff, light brown (7.5YR 6/3) dry. (1 to 5 inches thick.)
2R--47 inches; unweathered brown (7.5YR 4/4) tuff, light brown (7.5YR 6/3) dry.
TYPE LOCATION: Lake County, Oregon; on the Fremont National Forest about 4 miles east-northeast of Lakeview and southeast of Camas Prairie; in the NW1/4, SW1/4, SW1/4, section 8, T. 39 S., R. 21 E.; USGS Lakeview 7.5 minute topographic quadrangle.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist from late fall through spring, dry in summer and early fall; The moisture control section is dry for 45 to 60 consecutive days following the winter solstice; Xeric moisture regime.
Mean annual soil temperature - 42 to 46 degrees F.
Mean summer soil temperature - more than 46 degrees F.
Mollic epipedon thickness - 20 to 35 inches; includes all or the upper part of the argillic horizon.
Depth to bedrock - 40 to 60 inches to a paralithic contact. The paralithic materials below the contact are weathered volcanic rock such as tuff.
Particle-size control - Clay content: 35 to 50 percent;
Rock fragments: Averages 35 to 60 percent, mainly cobbles. Lithology of fragments are volcanic rocks such as basalt or tuff.
Base saturation - 60 to 85 percent in the upper 30 inches and less than 75 percent in the lower part.
A horizons
Value: 3 through 5 dry, 2 or 3 moist.
Chroma: 1 or 4 dry, 2 or 3 moist.
Rock fragments: 20 to 45 percent total with 0 to 15 percent boulders, 10 to 20 percent stones, 0 to 10 percent cobbles, and 5 to 25 percent gravel.
Reaction: Slightly acid or neutral.
Organic matter content: 4 to 6 percent.
2Bt horizons
Hue: 7.5YR through 2.5Y.
Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 3 through 6, dry or moist.
Texture: Very cobbly clay, very cobbly clay loam, very cobbly silty clay, or very stony clay loam.
Clay content: 35 to 50 percent.
Rock fragments: 35 to 60 percent total with 0 to 20 percent stones, 5 to 30 percent cobbles, and 10 to 30 percent gravel.
Reaction: Slightly acid or neutral.
Organic matter content: 1 to 3 percent.
2C horizon
Texture: Very paragravelly clay loam, extremely paragravelly clay loam, or gravelly clay loam.
Rock fragments: Less than 20 percent gravel.
Pararock fragments: 35 to 60 percent paragravel.
Reaction: Slightly acid or neutral.
COMPETING SERIES: This is the Isknat series. Isknat soils are very deep.
GEOGRAPHIC SETTING: Mound soils occur on hills, mountains, and plateaus. The soil formed in colluvium derived from volcanic rocks such as basalt over residuum weathered from tuff and basalt. Slopes are 0 to 70 percent. Elevations range from 4,700 to 6,500 feet. The climate is characterized by cold, wet winters and warm, dry summers. The mean annual precipitation is 16 to 25 inches, the mean annual temperature is 40 to 47 degrees F, and the frost-free period is 10 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nuss, Polander, Royst, and Winterim soils. Nuss soils are loamy and are 10 to 20 inches to bedrock. Polander soils have andic soil properties. Royst soils are 20 to 40 inches to bedrock. Winterim soils have a base saturation of over 75 percent throughout the profile and are at lower elevations.
DRAINAGE AND PERMEABILITY: Well drained; low to high surface runoff; slow permeability (moderately low or moderately high saturated hydraulic conductivity).
USE AND VEGETATION: Mound soils are used for timber production, livestock grazing, and wildlife habitat. The plant community is a forest consisting of ponderosa pine and white fir. The percentage of white fir increases on north-facing aspects. The understory plants consist of common snowberry, Wheeler's bluegrass, heartleaf arnica, starwart, and long-stolon sedge.
DISTRIBUTION AND EXTENT: South-central Oregon. These soils are moderately extensive. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Lake County, Oregon, Southern Part, 1991.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 2 to 31 inches (A1, A2, 2Bt1, and 2Bt2 horizons).
Argillic horizon - The zone from 15 to 31 inches (2Bt1 and 2Bt2 horizons).
Paralithic contact - The boundary at 44 inches to underlying weathered bedrock (2Cr layer).
The Ultic subgroup is based on laboratory data from similar soils in the area having the same plant community. The areas of Mound soil correlated into MLRA E-43 are Vitrandic and need to be recorrelated.