LOCATION NATAL OR+WAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Umbric Endoaqualfs
TYPICAL PEDON: Natal silty clay loam, pasture. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; common fine prominent brown (7.5YR 4/4) mottles; weak very fine subangular blocky structure; hard, friable, slightly sticky and plastic; many very fine and common fine roots; many very fine and common tubular and common medium irregular pores; moderately acid (pH 6.0); abrupt smooth boundary. (7 to 9 inches thick)
Bt1--9 to 16 inches; very dark grayish brown (2.5Y 3/2) silty clay, gray (10YR 6/1) dry; common fine prominent brown (7.5YR 4/4) mottles, strong brown (7.5YR 5/6) dry, and few fine prominent yellowish red (5YR 5/8) mottles; strong fine subangular blocky structure; hard, firm, sticky and very plastic; few distinct clay films on ped faces; many very fine roots; many very fine and few fine tubular pores and common medium irregular pores; moderately acid (pH 5.8); clear smooth boundary.
Bt2--16 to 23 inches; very dark grayish brown (2.5Y 3/2) silty clay, gray (10YR 6/1) dry; common fine prominent brown (7.5YR 4/4) mottles, strong brown (7.5YR 5/6) dry; strong medium angular blocky structure; very hard, firm, sticky and very plastic; few faint clay films on ped faces and in pores; common very fine roots; common very fine and fine tubular and medium irregular pores; strongly acid (pH 5.4); clear smooth boundary.
Bt3--23 to 40 inches; dark grayish brown (2.5Y 4/2) silty clay, gray (10YR 6/1) dry; common fine prominent brown (7.5YR 4/4) and very dark gray (N 3/0) mottles, strong brown (7.5YR 5/6) and grayish brown (10YR 5/2) dry; weak medium angular blocky structure; very hard, firm, sticky and very plastic; few distinct clay films on ped faces and in pores; common very fine roots; common very fine and fine tubular pores; strongly acid (pH 5.4); gradual wavy boundary. (Combined thickness of the Bt horizon is 22 to 51 inches)
BCt--40 to 53 inches; very dark grayish brown (2.5Y 3/2) silty clay, grayish brown (10YR 5/2) dry; many fine prominent strong brown (7.5YR 5/6) and dark grayish brown (2.5Y 4/2) mottles; massive; very hard, firm, sticky and very plastic; few faint clay films in pores; few very fine roots; common very fine and fine tubular pores; strongly acid (pH 5.2); gradual smooth boundary. (0 to 15 inches thick)
C--53 to 64 inches; dark grayish brown (2.5Y 4/2) silty clay, light gray (2.5Y 7/2) dry; many fine prominent strong brown (7.5YR 5/6) and very dark grayish brown (2.5Y 3/2) mottles; massive; very hard, firm, sticky and very plastic; common very fine and fine tubular pores; strongly acid (pH 5.2).
TYPE LOCATION: Columbia County, Oregon; 400 yards east of Highway 47, 80 yards south of gravel road; center of section 34, T. 5 N., R. 4 W.
RANGE IN CHARACTERISTICS: The soil is saturated with water from November through May and is dry for less than 45 consecutive days between 4 and 12 inches. The mean annual soil temperature is 49 to 54 degrees F. Solum thickness ranges from 40 to more than 60 inches.
The A horizon typically has hue of 10YR, but some pedons range to 5Y, value of 2 or 3 moist, 3 to 5 dry, and chroma of 1 or 2 moist and dry. Clay content is 27 to 35 percent. It is strongly acid to slightly acid. Shallow cracks may appear when the soil is dry.
The Bt horizon has value of 3 to 5 moist, 4 through 7 dry, and chroma of 1 or 2 moist and dry. It has prominent brown or strong brown redox concentrations as masses and very dark gray or very dark grayish brown redox depletions. This horizon in some pedons, has grayish brown (10YR 5/2) stains when dry. Clay content is 40 to 60 percent. It is very strongly acid to moderately acid in the upper part and very strongly acid to slightly acid in the lower part. Rock fragments range from 0 to 5 percent.
The BCt and C horizons, when present, have hue of 2.5Y moist and 10YR or 2.5Y dry, value of 3 or 4 moist, 5 through 7 dry, and chroma of 1 or 2 moist and dry. It has prominent strong brown redox concentrations as masses and dark grayish brown or very dark grayish brown redox depletions. Clay content is 40 to 60 percent. It is very strongly acid to neutral.
COMPETING SERIES: There are no other series in this family. The Minniece series is similar; it has an umbric epipedon.
GEOGRAPHIC SETTING: Natal soils are on stream terraces at elevations of 20 to 800 feet. Slopes range from 0 to 4 percent. These soils formed in alluvium from mixed sources under a cool moist climate. The mean July temperature is 60 to 64 degrees F., the mean January temperature is 35 to 37 degrees F., and the mean annual temperature is 47 to 53 degrees F. The mean annual precipitation is 45 to 90 inches. The frost-free season is 110 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Eilertsen, McNulty, and Treharne soils. Eilertsen and Treharne soils are fine-silty and are on slightly higher adjacent terrace positions. McNulty soils are coarse-loamy soils on flood plains.
DRAINAGE AND PERMEABILITY: Poorly drained; ponded; slow permeability. Depth to a seasonal high water table is at the surface to 1 foot December through April.
USE AND VEGETATION: The soils are used for hay, pasture, recreation, homesite development and wildlife habitat. Native vegetation is western redcedar, willow, ash, alder, dogwood, spirea, sedges, and rushes.
DISTRIBUTION AND EXTENT: Low valley terraces of the Coast Range in Northwestern Oregon and Southwestern Washington. This series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Columbia County, Oregon, 1983.
REMARKS: This draft reflects a change in classification from Umbric Ochraqualfs to Umbric Endoaqualfs based on amendment 16 to Soil Taxonomy.
Diagnostic horizons and features included in this pedon:
Ochric epipedon - from the surface to 9 inches (Ap horizon)
Argillic horizon - from 9 to 53 inches (Bt1, Bt2, Bt3, and BCt horizons)
Aquic conditions - redox depletions with dominant chroma of 2 or less in the matrix of the argillic horizon and redox concentrations as masses with higher chroma.