LOCATION KOSMOS WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Endoaqualfs
TYPICAL PEDON: Kosmos silt loam - under a coniferous forest on a 1 percent south-facing slope at an elevation of 360 feet. The soil was moist throughout when described. (Colors are for moist soil unless otherwise stated.)
Ag1--0 to 7 inches; dark gray (10YR 4/1) silt loam, light gray (10YR 6/1) dry; strong fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many fine, medium and coarse roots; many fine irregular pores; moderately acid (pH 5.8); clear smooth boundary.
Ag2--7 to 12 inches; gray (10YR 5/1) silty clay loam, light gray (10YR 6/1) dry; common fine distinct reddish brown (5YR 4/4) mottles, strong brown (7.5YR 5/6) dry; strong fine and medium subangular blocky structure; hard, friable, sticky and plastic; many fine and medium roots; common fine and few coarse tubular pores and many fine irregular pores; moderately acid (pH 5.8); clear smooth boundary. (Combined thickness of the Ag horizon is 9 to 14 inches)
Btg1--12 to 17 inches; gray (5Y 5/1) silty clay loam, light gray (10YR 6/1) dry; many medium prominent reddish brown (5YR 4/4) mottles, strong brown (7.5YR 5/6) dry; moderate medium subangular blocky structure; hard, firm, sticky and plastic; common fine and medium roots; many fine and few medium tubular pores; few thin patchy clay films lining some pores; moderately acid (pH 5.6); clear smooth boundary. (4 to 6 inches thick)
2Btg2--17 to 37 inches; gray (5Y 5/1) sandy clay loam, light gray (10YR 7/1) dry; many coarse prominent reddish brown (5YR 4/4) mottles, yellowish red (5YR 4/6) and red (2.5YR 4/8) dry; moderate coarse prismatic structure; hard, firm, slightly sticky and slightly plastic; few fine roots; many fine, common medium, and few coarse tubular pores; few thin patchy clay films lining pores; strongly acid (pH 5.4); clear smooth boundary. (18 to 20 inches thick)
2Btg3--37 to 47 inches; gray (5Y 5/1) sandy clay loam light gray (10YR 6/1) dry; many medium prominent reddish brown (5YR 4/4) mottles, yellowish red (5YR 4/6, 4/8) dry; moderate coarse prismatic and moderate medium subangular blocky structure; hard, firm, sticky and very plastic; few fine roots; many fine and medium tubular pores; few patchy clay films lining some pores; moderately acid (pH 5.6); clear smooth boundary. (8 to 11 inches thick)
2Cg1--47 to 56 inches; grayish brown (2.5Y 5/2) sandy clay loam, light gray (10YR 7/2) dry; common medium prominent reddish brown (5YR 4/4) mottles, yellowish red (5YR 5/6) and strong brown (7.5 YR 5/6) dry; massive; very hard, friable, sticky and nonplastic; few fine roots; common fine and few medium tubular pores; few thin clay films lining pores; strongly acid (pH 5.4); clear smooth boundary. (8 to 10 inches thick)
3Cg2--56 to 60 inches; grayish brown (2.5Y 5/2) coarse sandy loam, light brownish gray (10YR 6/2) dry; many medium distinct dark brown (7.5YR 4/4) mottles yellowish red (5YR 5/6) dry; massive; hard, very friable, nonsticky and nonplastic; few fine roots; common fine and medium and few coarse tubular pores; and many fine irregular pores; moderately acid (pH 5.6).
TYPE LOCATION: Cowlitz County, Washington. Approximately 6.5 miles northeast of Castle Rock. About 1,700 feet east and 500 feet north of the southwest corner section 1, T. 10 N., R. 1 W.
RANGE IN CHARACTERISTICS: Average annual soil temperature at 20 inches ranges from 52 to 54 degrees F. The particle-size control section averages 0 to 5 percent rock fragments. Solum thickness is 42 to 60 inches. Reaction ranges from moderately acid to strongly acid throughout.
The Ag horizon has value of 4 or 5 moist and chroma of 1 or 2 moist and dry, and is mottled below 7 inches. It is silt loam or silty clay loam in the lower part.
The Btg horizon has hue of 5Y through 10YR, value of 4 or 5 moist, and chroma of 1 or 2 moist and dry. Mottling in the B horizon ranges from distinct to prominent. It is silty clay loam, clay loam, or sandy clay loam.
The 2Cg horizon is coarse sandy loam, sandy loam, or sandy clay loam.
COMPETING SERIES: There are no competing series. Similar soils in other families are the Damascus and Ruark series. Damascus soils have a solum 30 to 42 inches thick and 10 to 50 percent rock fragments from 20 to 40 inches. Ruark soils have an E horizon and are in a climate with moist summers.
GEOGRAPHIC SETTING: Kosmos soils are on terraces at elevations of 300 to 400 feet. These soils formed in glaciofluvial material (possibly old volcanic mudflow). The climate is marine and characterized by warm, dry summers and cool, moist winters. The average annual precipitation is 50 to 60 inches mostly as rainfall. The average July temperature is about 65 degrees F. The average January temperature is about 35 degrees F. The average annual air temperature is about 50 degrees F. The frost-free season is 165 to 180 days. The growing season is 220 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Olympic, Seaquest, and Speelyai soils. Olympic and Seaquest soils have a xeric moisture regime and are well drained. Speelyai soils lack an argillic horizon, have a xeric moisture regime, and are moderately well drained.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained, slow runoff; slow permeability. Depth to a perched seasonal water table is from the surface to 2 feet from November to May.
USE AND VEGETATION: Use mainly for timber production. Cleared areas are used for hay and pasture. Native vegetation is Douglas-fir, Oregon ash, western redcedar, red alder, and black cottonwood, with an understory of salal, western hazel, vine maple, western brackenfern, western swordfern, rose, evergreen blackberry, willow, red elderberry, Oregon-grape, and salmonberry.
DISTRIBUTION AND EXTENT: Cowlitz County, Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lewis County, Washington, 1941.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the surface to 12 inches and an argillic horizon from 12 to 47 inches. These soils were correlated Minniece, loamy variant in the 1974 Soil Survey of the Cowlitz Area, Washington. This description reflects a change in classification based on amendment 16.