LOCATION SEKIU WAEstablished Series
TAXONOMIC CLASS: Fine, isotic, acid, isomesic Typic Humaquepts
TYPICAL PEDON: Sekiu silty clay loam - forested. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures. This profile was very wet when described.)
Oi--0 to 1 inch; slightly decomposed.
Oe--1 to 5 inches; moderately decomposed needles, leaves, and twigs; very dark brown (10YR 2/2) moist, very dark grayish brown (10YR 3/2) dry; many fine, very fine, and medium roots; extremely acid (pH 4.2); abrupt smooth boundary.
A--5 to 13 inches; very dark grayish brown (10YR 3/2) silty clay loam, dark grayish brown (10YR 4/2) dry; few fine distinct dark grayish brown (10YR 4/2) redox features, light brownish gray (10YR 6/2) dry; weak fine medium angular blocky structure; hard, firm, very sticky and very plastic; many fine and very fine roots; many fine and very fine tubular and many very fine irregular pores; extremely acid (pH 4.4); clear smooth boundary. (6 to 8 inches thick)
Bg1--13 to 21 inches; dark grayish brown (10YR 4/2) silty clay loam, light brownish gray (10YR 6/2) dry; many medium distinct yellowish brown (10YR 5/6) and very dark grayish brown (10YR 3/2) redox features, brownish yellow (10YR 6/8) and grayish brown (10YR 5/2) dry; weak fine and medium angular blocky structure; hard, firm, very sticky and very plastic; common very fine roots; common fine and very fine tubular pores; very strongly acid (pH 4.6); clear smooth boundary. (8 to 10 inches thick)
Bg2--21 to 31 inches; dark grayish brown (2.5Y 4/2) silty clay loam, light brownish gray (2.5Y 6/2) dry; common medium distinct light olive brown (2.5Y 5/4) and strong brown (7.5YR 5/8) redox concentrations, light yellowish brown (2.5Y 6/4) and reddish yellow (7.5YR 6/8) dry; massive; very hard, firm very sticky and very plastic; few very fine roots; few fine and very fine tubular pores; very strongly acid (pH 4.6); clear smooth boundary. (10 to 14 inches thick)
Bg3--31 to 65 inches; gray (5Y 5/1) silty clay loam, light gray (5Y 6/1) dry; common medium distinct olive (5Y 4/4) redox concentrations, pale olive (5Y 6/4) dry; massive; very hard, firm, very sticky and very plastic; few very fine roots; few very fine tubular pores; very strongly acid (pH 4.8).
TYPE LOCATION: Jefferson County, Washington; about 1,100 feet east of highway 101, 2,400 feet north and 2,800 feet west of the SE corner of sec. 22, T. 24 N., R. 13 W.
RANGE IN CHARACTERISTICS: The particle-size control section lacks rock fragments and has 35 to 70 percent clay in various horizons and averages 35 to 60 percent clay. The solum is 14 to 18 inches thick. The mean annual soil temperature is estimated to range from 48 to 50 degrees F. The water table is at or near the surface from October to July.
The A horizon has hue of 7.5YR or 10YR moist and dry, value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 or 2 moist or dry. It has angular blocky or prismatic structure. This horizon is very strongly acid or extremely acid. It has few to common distinct redox features.
The Bg1 horizon has hue of 10YR through 5Y moist and dry, value of 4 through 6 moist, 6 or 7 dry, and chroma of 1 or 2 moist and dry. It is predominantly silty clay loam, but ranges to silty clay. This horizon has angular blocky or prismatic structure. It has common to many distinct or prominent redox features.
The Bg2 and Bg3 horizon has hue of 2.5Y through 5GY moist and dry, value of 4 through 6 moist, 6 or 7 dry, and chroma of 1 or 2 moist and dry. It is silty clay loam or silty clay. This horizon has common to many distinct or prominent redox concentrations.
COMPETING SERIES: This is the Nemah series. Nemah soils have a gravelly or very gravelly 2C horizon at a depth of 30 to 40 inches.
GEOGRAPHIC SETTING: Sekiu soils are in depressions on terraces at elevations of 50 to 200 feet. Slopes are 0 to 2 percent. The soils formed in fine alluvium within approximately 3 miles of the Pacific Ocean. The climate is characterized by cool, moist summers and cool, wet winters. The mean annual precipitation is 90 to 110 inches. Average January temperature is about 37 degrees F., average July temperature is about 57 degrees F., and the mean annual temperature is about 47 degrees F. Frost-free season is 180 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hoko, Klone, and Tealwhit soils. Hoko soils are skeletal and have a paralithic contact consisting of very compact glacial till at a depth of 20 to 40 inches. Klone soils are medial-skeletal. Tealwhit soils have chroma of more than 2 in some part of the upper 20 inches.
DRAINAGE AND PERMEABILITY: Very poorly drained, very slow runoff to ponded; slow or very slow permeability.
USE AND VEGETATION: Timber production is the principal use. Native vegetation is predominantly western redcedar with some Sitka spruce, western hemlock, and lodgepole pine. Understory species are salal, red huckleberry, evergreen huckleberry, western swordfern, deer fern, and skunk cabbage.
DISTRIBUTION AND EXTENT: Northwestern Washington. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clallam County, Washington, 1943.
REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy. This soil would be in a Vertic subgroup if such were provided in Soil Taxonomy.
This draft reflects a change in type location and in family classification from kaolinitic to mixed mineralogy. Partial laboratory data are available on this soil. Laboratory numbers 791761-4.