LOCATION HOREB OR
Established Series
Rev. AON/RWL
06/2011
HOREB SERIES
The Horeb series consists of very deep, moderately well drained soils formed in colluvium and glacial till derived from mixed materials. Horeb soils are on terraces and mountain footslopes. Slopes are 0 to 35 percent. The mean annual precipitation is about 80 inches. The mean annual temperature is about 48 degrees F.
TAXONOMIC CLASS: Fine-loamy, isotic, mesic Oxyaquic Humudepts
TYPICAL PEDON: Horeb loam, forested. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 2 inches; slightly decomposed organic litter of fern leaves, needles, leaves, twigs, etc.
A1--2 to 11 inches; very dark brown (10YR 2/2) loam, dark gray (10YR 4/1) dry; moderate fine granular structure; slightly hard, very friable, nonsticky and nonplastic; many roots; many fine and very fine irregular pores; 5 percent gravel; strongly acid (pH 5.2); gradual wavy boundary. (6 to 12 inches thick)
A2--11 to 16 inches; very dark grayish brown (10YR 3/2) loam, brown (10YR 5/3) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; many fine and very fine irregular pores; 10 percent gravel; strongly acid (pH 5.4); clear wavy boundary. (4 to 8 inches thick)
Bw1--16 to 26 inches; brown (10YR 4/3) gravelly loam, light yellowish brown (10YR 6/4) dry; moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common roots; common very fine pores; 20 percent gravel; very strongly acid (pH 4.8); clear wavy boundary. (8 to 14 inches thick)
Bw2--26 to 33 inches; dark yellowish brown (10YR 4/4) gravelly loam, light yellowish brown (10YR 6/4) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few roots; many very fine pores; 25 percent gravel; very strongly acid (pH 4.8); clear wavy boundary. (5 to 10 inches thick)
C1--33 to 38 inches; dark grayish brown (2.5Y 4/2) gravelly loam, pale yellow (2.5Y 8/4) dry; common medium distinct yellowish brown (10YR 5/6) redox concentrations; massive; slightly hard, friable, slightly sticky and slightly plastic; few roots; common very fine pores; 25 percent gravel; very strongly acid (pH 4.8); clear wavy boundary. (4 to 8 inches thick)
C2--38 to 62 inches; dark grayish brown (2.5Y 4/2) cobbly loam, pale yellow (2.5Y 8/4) dry; common medium distinct yellowish brown (10YR 5/6) redox concentrations; massive; hard, firm, moderately sticky and moderately plastic; few roots; many very fine and few medium pores; 15 percent gravel and 20 percent cobbles; very strongly acid (pH 4.8).
TYPE LOCATION: Marion County, Oregon; 30 feet west of logging road; NE1/4 NW1/4 sec. 15, T. 9 S., R. 3E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 50 degrees F. The solum ranges from 24 to 40 inches thick. Rock fragments in the 10- to 40-inch control section range from 10 to 25 percent. Soils are usually moist but are dry in all parts of the soil moisture control section for less than 45 consecutive days in the four months following the summer solstice. Umbric epipedon is 10 to 20 inches thick.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 or 2 moist and dry in the upper part and 2 or 3 moist and dry in the lower part. It is strongly or very strongly acid.
The B horizon has hue of 7.5YR or 10YR, value of 5 or 6 dry and chroma of 3 or 4 moist and dry. It is loam with 18 to 27 percent clay, has more than 15 percent coarser than very fine sand, and has 10 to 25 percent pebbles. Some pedons have up to 15 percent cobbles.
The C horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist and 6 through 8 dry, and chroma of 2 through 4 moist and dry. Redox features with chroma of 2 through 6 are at depths of 24 to 36 inches. The C horizon below a depth of 40 inches is loam with 25 to 85 percent rock fragments. In some pedons it is very gravelly sand.
COMPETING SERIES: These are the
Bohannon,
Hembre,
Meda,
Nelscott,
Preacher,
Stevenson and
Wadell series. Bohannon soils are 20 to 40 inches deep to bedrock, are well drained, and lack mottles. Hembre soils have a B horizon with hue of 5YR and textures of silty clay loam or heavy silt loam and lack mottles. Meda soils have a clay loam B horizon and lack mottles in the C horizon. Nelscott soils have a clay loam B2 horizon, lack mottles above 36 inches, and are underlain by sandy marine sediments below a depth of 40 inches. Preacher soils have a clay loam B horizon and lack mottles. Stevenson soils have sola thicker than 40 inches, are well drained and lack low chroma mottles. Wadell soils have sola thicker than 40 inches, are well drained and lack mottles.
GEOGRAPHIC SETTING: Horeb soils are on terraces and mountain footslopes with gradients of 0 to 35 percent and at elevations of 1,500 to 3,500 feet. The soils formed in medium textured colluvium and glacial till from mixed materials. The climate is humid temperate with a mean annual precipitation of 70 to 90 inches, a mean annual temperature of 45 to 50 degrees F., a mean January temperature of 36 degrees F., and a mean July temperature of 62 degrees F. The frost-free season is 120 to 165 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Cumley,
Kinney, and McCully soils. Cumley soils have a clayey argillic horizon. Kinney soils are moderately fine textured, lack redox features, and have evidence of amorphous clays. McCully soils are fine-textured.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium runoff; moderate permeability. Apparent water table at 2.5 to 6.0 feet from November to May.
USE AND VEGETATION: Timber production, Douglas-fir, bigleaf maple, alder, huckleberry, sandfern, brackenfern.
DISTRIBUTION AND EXTENT: These soils are on footslopes of the Cascade Mountains in Oregon. MLRA 3. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Marion County, Oregon, 1973.
REMARKS: Diagnostic horizons and other features:
Umbric epipedon - 2 to 16 inches
Cambic horizon - 16 to 33 inches
National Cooperative Soil Survey
U.S.A.