LOCATION CHEHULPUM OREstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, mesic, shallow Ultic Haploxerolls
TYPICAL PEDON: Chehulpum silt loam-grass and oak. (Colors are for moist soil unless otherwise noted.)
A1--0 to 4 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; moderate fine granular structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine irregular and tubular pores; moderately acid (pH 5.9); clear smooth boundary. (4 to 10 inches thick)
A2--4 to 12 inches; very dark brown (10YR 2/2) paragravelly silt loam, dark grayish brown (10YR 4/2) dry; moderate medium and fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine and fine tubular pores; 15 percent sandstone and siltstone paragravel; moderately acid (pH 5.9); abrupt smooth boundary. (6 to 10 inches thick)
2Cr--12 to 20 inches; semiconsolidated sandstone.
TYPE LOCATION: Marion County, Oregon; about 100 feet west and 300 feet south of the NE corner of section. 25, T. 9 S., R. 3 W. Willamette Meridian, Turner, Oregon USGS 7.5 minute topographic quadrangle. Latitude 44 degrees, 45 minutes, 57 seconds N. and Longitude 122 degrees, 59 minutes, 18 seconds W.; NAD27
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 52 to 56 degrees F. The soils are usually moist but are dry in all parts from a depth of 4 to 12 inches for 60 to 80 days following the summer solstice. Thickness of the mollic epipedon is 10 to 20 inches. Depth to semiconsolidated bedrock ranges from 10 to 20 inches. Hue is 10YR or 7.5YR. The pscs has 18 to 30 percent clay. Reaction is moderately acid or slightly acid.
The A1 horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 2 or 3 moist and dry. Texture is silt loam with 18 to 27 percent clay. It has 0 to 5 percent gravel and 0 to 10 percent paragravel.
The A2 horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 2 or 3 moist and dry. Texture is silt loam, silty clay loam, loam or clay loam with 20 to 30 percent clay. It has 0 to 20 percent gravel, 0 to 5 percent cobbles and 5 to 35 percent paragravel.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: The Chehulpum soils are on low hills at elevations of 200 to 1,200 feet. The soils formed in colluvium derived from sedimentary rocks mixed with silty glaciolacustrine deposits at elevations below 400 feet. Slopes are 3 to 60 percent. The climate is characterized by warm, wet winters and hot, dry summers. The average annual precipitation is 40 to 60 inches. The average July temperature is 67 degrees F. and average January temperature is 39 degrees F. The average annual temperature is 50 to 54 degrees F. The frost-free period is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dupee, Hazelair, Steiwer, Willakenzie and Yamhill soils. Dupee soils are greater than 40 inches to a paralithic contact and are on footslopes and concave parts of hillslopes. Hazelair soils are fine and have redox depletions within 30 inches of the surface and are on concave parts of hillslopes. Steiwer soils are 20 to 40 inches to a paralithic contact and are on the linear parts of hillslopes. Willakenzie soils are fine-loamy, do not have a mollic epipedon and are on low hills. Yamhill soils are fine, have a mollic epipedon greater than 20 inches thick and occur over basalt on low hills.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: These soils are used mainly for native pasture, wildlife habitat and watershed. Native vegetation is annual grasses, wild rose, oak, and poison-oak.
DISTRIBUTION AND EXTENT: Low foothills of the Willamette Valley, Oregon; MLRA 2. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Marion Area, Marion County, Oregon, 1973.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - the zone from 0 to 12 inches (A1 and A2 horizons)
Ultic feature - the zone between 10 and 12 inches having a base saturation (sum) of 75 percent or less.