LOCATION RAFTON OREstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, mesic Fluvaquentic Endoaquepts
TYPICAL PEDON: Rafton silt loam, protected, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; common fine prominent yellowish red (5YR 4/8 and 5/8) redox concentrations; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; moderately acid (pH 6.0); abrupt smooth boundary. (8 to 10 inches thick)
Bw1--9 to 21 inches; grayish brown (10YR 5/2) silt loam, light gray (10YR 7/2) dry; many fine and medium prominent yellowish red (5YR 5/6 and 5/8) redox concentrations; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine tubular pores, mostly vertical; thin brown coatings in pores; slightly acid (pH 6.2); clear wavy boundary. (10 to 15 inches thick)
Bw2--21 to 40 inches; mottled brown (10YR 4/3) gray (10YR 5/1) silt loam, gray (10YR 6/1), light gray (10YR 7/1 and 7/2), and reddish yellow (7.5YR 6/6) dry; many medium grayish brown (10YR 5/2) and common fine yellowish red (5YR 5/8) coatings in vertical pores; weak medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; common very fine roots; common fine and few medium tubular pores, mostly vertical; slightly acid (pH 6.2); clear wavy boundary. (15 to 25 inches thick)
C1--40 to 55 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; many medium and fine prominent reddish brown (5YR 4/4) yellowish red (5YR 5/8) and red (2.5YR 4/6) redox concentrations; massive; hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine tubular pores; slightly acid (pH 6.2); clear wavy boundary. (15 to 20 inches thick)
2HC2--55 to 60 inches; very dark gray (5Y 3/1) silt loam, common medium prominent yellowish red (5YR 5/8) and red (2.5YR 4/6) redox concentrations lining pores; massive; hard, friable, nonsticky and slightly plastic; many medium tubular pores; slightly acid (pH 6.2).
TYPE LOCATION: Multnomah County, Oregon; 90 feet north of drainage ditch; SW1/4 NW1/4 NE1/4 section 30, T.3N., R.1W., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 53 to 55 degrees F. The soils are saturated with water throughout the year and subject to freshwater overflow during high tides and spring floods unless diked and artificially drained.
The A horizon has value of 4 or 5 moist, 6 or 7 dry and chroma of 1 or 2 moist and dry. This horizon has moderate to strong granular or subangular blocky structure.
The B horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist, 6 or 7 dry, and chroma of 1 or 2 moist and dry. It has distinct or prominent mottles. This horizon is silt loam or silty clay loam and has 20 to 30 percent clay and less than 15 percent coarser than very fine sand. Thin lenses totaling one inch or less of peaty or loamy material with value of 2 or 3 and chroma of 1 are in some pedons.
The C horizon has hue of 10YR, 2.5Y or 5Y, value of 4 or 5 moist and chroma of 0, 1 or 2. It is composed of stratified material ranging from silty clay loam to sandy loam. Redox concentrations are distinct to prominent with areas having dark brown (7.5YR 3/2) "pipestems" up to 1/4 inch in diameter formed in tubular pores and channels. Thin layers of gray (10YR 6/1) ash-like material are in some pedons.
COMPETING SERIES: These are the Nookachamps and Skagit series. Nookachamps soils are neutral or mildly alkaline. Skagit soils have 20 to 50 percent glass.
GEOGRAPHIC SETTING: The Rafton soils are on broad flood plains of the Columbia River at elevations of 10 to 20 feet. Slopes are 0 to 2 percent. The soils formed in silty recent alluvium of mixed origin. The winters are cool and moist and summers are warm and dry. The mean January temperature is about 40 degrees F.; mean July temperature is about 68 degrees F.; and the mean annual temperature is about 53 degrees F. The frost-free season is about 165 to 210 days. The mean annual precipitation ranges from 40 to 60 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Moag and Sauvie soils. Moag soils are fine textured. Sauvie soils have a mollic epipedon, are poorly drained, and lack prominent redox concentrations above a depth of 20 inches.
DRAINAGE AND PERMEABILITY: Very poorly drained; ponded; moderate permeability.
USE AND VEGETATION: These soils are used for improved hay, pasture and truck crops. Areas outside of dikes are in native vegetation or used for pasture and wildlife habitat. Where this soil is not cultivated the vegetation is black cottonwood, willow, rose, common snowberry, sedges, cattails and grasses.
DISTRIBUTION AND EXTENT: Flood plains of the lower Columbia River, Oregon. The soil is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Multnomah County, Oregon, 1977.
REMARKS: Diagnostic horizons and other features:
Ochric epipedon
Cambic horizon - 9 to 40 inches