LOCATION COTTRELL OREstablished Series
TAXONOMIC CLASS: Fine, mixed, active, mesic Aquic Haplohumults
TYPICAL PEDON: Cottrell silty clay loam - cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 6 inches; very dark grayish brown (10YR 3/2) silty clay loam, dark grayish brown (10YR 4/2) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine irregular pores; many fine concretions; medium acid (pH 6.0); clear smooth boundary. (4 to 8 inches thick)
A1--6 to 12 inches; dark brown (10YR 3/3) silty clay loam, brown (10YR 5/3) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fineand fine roots; many fine and very fine tubular pores; common fine concretions; strongly acid (pH 5.2); clear smooth boundary. (4 to 8 inches thick)
A2--12 to 15 inches; dark brown (7.5YR 3/3) silty clay loam, brown (7.5YR 5/3) dry; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic; many fine and very fine roots; many very fine tubular pores; strongly acid (pH 5.2); clear smooth boundary. (0 to 6 inches thick)
BA--15 to 24 inches; dark brown (7.5YR 4/4) silty clay loam, brown (7.5YR 5/4) dry; moderate fine subangular blocky structure; hard, firm, sticky and plastic; common fine and very fine roots; common very fine tubular pores; few thin yellowish red (5YR 4/6) clay films; 5 percent fine weathered gravel; strongly acid (pH 5.4); clear smooth boundary. (0 to 10 inches thick)
Bt1--24 to 42 inches; dark brown (7.5YR 4/4) silty clay, brown (7.5YR 5/4) dry; common fine distinct yellowish red (5YR 5/6) and grayish brown (10YR 5/2) mottles; moderate coarse subangular blocky structure; very hard, very firm, sticky and very plastic; few fine and very fine roots; common very fine tubular pores; common moderately thick yellowish red (5YR 4/6) clay films; 10 percent fine weathered gravel; strongly acid (pH 5.4); clear smooth boundary. (15 to 24 inches thick)
Bt2--42 to 55 inches; dark brown (7.5YR 4/4) silty clay, brown (7.5YR 5/4) dry; common medium distinct yellowish red (5YR 5/6) and grayish brown (10YR 5/2) mottles; moderate fine subangular blocky structure; hard, firm, sticky and very plastic; common very fine roots; common very fine tubular pores; many moderately thick yellowish red (5YR 4/6) clay films; common medium black concretions; strongly acid (pH 5.4); clear wavy boundary. (10 to 20 inches thick)
BCt--55 to 86 inches; reddish brown (5YR 4/4) silty clay loam, yellowish red (5YR 5/6) dry; common fine distinct yellowish red
(5YR 5/7) and grayish brown (10YR 5/2) mottles; weak fine subangular blocky structure; slightly hard, friable, sticky and plastic; common very fine tubular pores; common thin yellowish red (5YR 4/6) clay films; common medium black stains; strongly acid (pH 5.4).
TYPE LOCATION: Clackamas County, Oregon; about 1/2 mile northwest of Sandy, Oregon; in the SE1/4NW1/4NE1/4 section 14, T. 2 S., R. 4 E.
RANGE IN CHARACTERISTICS: The soil is saturated with water during the winter and early spring unless artificially drained. The mean annual soil temperature is 52 to 55 degrees F. The solum is 50 to 60 or more inches thick.
The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. The A and BA horizon is medium acid to strongly acid.
The Bt horizon has hue of 7.5YR or 5YR, value of 5 or 6 dry, and chroma of 3 or 4 moist and dry. It has distinct mottles with value of 4 or 5 moist and chroma of 2 moist within the upper 10 inches. It is silty clay or clay and averages 40 to 50 percent clay.
The BCt horizon has hue of 5YR or 7.5YR, value of 4 or 5 moist, 5 or 6 dry, and chroma of 4 through 6 moist and dry. It is silty clay loam or light silty clay. It is underlain by variegated weathered gravelly alluvium commonly deeper than 60 inches.
COMPETING SERIES: These are the Chismore, Mayger and Suver series. Chismore and Mayger soils have hue yellower than 7.5YR in the argillic horizon and are very strongly acid. Suver soils are 40 to 60 inches deep to a paralithic contact and have 55 to 70 percent clay in the argillic horizon, have a sola thickness of less than 50 inches, and are somewhat poorly drained. GEOGRAPHIC SETTING: Cottrell soils are on high old alluvial terraces at elevations of 600 to 900 feet. Slopes are 2 to 30 percent. The soils formed in mixed old alluvium. Summers are warm and moist and winters are cool and wet. Mean annual precipitation is 45 to 80 inches, mean annual temperature is 50 to 53 degrees F., and the frost-free season is 140 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cazadero, Borges, Jory, and Nekia soils. Cazadero and Jory soils lack mottles. Borges soils have chroma of 2 or less throughout the profile. Nekia soils are 20 to 40 inches deep to bedrock.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow or medium runoff; moderately slow permeability.
USE AND VEGETATION: The soils are used for row crops, berries, nursery crops, hay, pasture, and grains. Native vegetation dominantly is Douglas-fir, red alder, western redcedar, and trailing blackberry.
DISTRIBUTION AND EXTENT: Northwest Oregon. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clackamas County, Oregon, 1982.
ADDITIONAL DATA: Laboratory data sample No. S77OR-3-1 Oregon State University.