LOCATION SEVENOAKS OREstablished Series
TAXONOMIC CLASS: Mixed, mesic Psammentic Haploxerolls
TYPICAL PEDON: Sevenoaks loamy sand, on a 1 percent slope in a cultivated area. (Colors are for moist soil unless otherwise noted.)
Ap1--0 to 7 inches; very dark brown (10YR 2/2) loamy sand, dark grayish brown (10YR 4/2) dry; weak medium and coarse subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; very few fine roots; many fine irregular pores; 10 percent fine pumice gravel; moderately acid (pH 6.0); abrupt smooth boundary. (5 to 8 inches thick)
Ap2--7 to 14 inches; very dark brown (10YR 2/2) loamy sand, dark grayish brown (10YR 4/2) dry; massive; slightly hard, friable, nonsticky and nonplastic; very few fine roots; many fine irregular pores; 10 percent fine pumice gravel; very few fine roots; many fine irregular pores; 10 percent fine pumice gravel; moderately acid (pH 6.0); clear smooth boundary. (5 to 8 inches thick)
AC--14 to 22 inches; dark brown (10YR 3/3) gravelly sand, brown (10YR 5/3) dry; single grain; loose; very friable, nonsticky and nonplastic; very few fine roots; many fine irregular pores; 15 percent pumice gravel; slightly acid (pH 6.4); gradual wavy boundary. (5 to 9 inches thick)
C1--22 to 54 inches; dark olive brown (2.5Y 3/3) gravelly coarse sand, light olive brown (2.5Y 5/3) dry; single grain; loose; nonsticky and nonplastic; very few fine roots; many fine irregular pores; 20 percent fine pumice gravel; slightly acid (pH 6.4); clear wavy boundary. (29 to 33 inches thick)
C2--54 to 60 inches; dark grayish brown (2.5Y 4/2) gravelly sand, grayish brown (2.5Y 5/2) dry; single grain; loose; nonsticky and nonplastic; many fine irregular pores; 20 percent fine pumice gravel; slightly acid (pH 6.4).
TYPE LOCATION: Jackson County, Oregon; about 1 mile south of Upper Table Rock, approximately 1,800 feet west and 220 feet south of the northeast corner of sec. 15, T. 36 S., R. 2 W.
RANGE IN CHARACTERISTICS: Depth to bedrock is 60 inches or more. Pumice sand and gravel average 10 to 50 percent. The particle-size control section averages 15 to 30 percent gravel and 0 to 5 percent clay. The mean annual soil temperature is 52 to 56 degrees F.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It has 0 to 15 percent gravel. It has 1 to 3 percent organic matter. It is moderately or slightly acid.
The C horizon has hue of 10YR or 2.5Y, value of 3 or 4 moist, 5 or 6 dry, and chroma of 2 or 3 moist and dry. It is gravelly sand, gravelly coarse sand, or gravelly loamy sand. It has 15 to 30 percent gravel. It is moderately or slightly acid.
COMPETING SERIES: These are the Francis, La Posta, and Wasatch series. Francis soils are mildly to moderately alkaline and are loamy fine sand or fine sand in the particle-size control section. La Posta soils are 20 to 40 inches to a paralithic contact. Wasatch soils contain less than 15 percent gravel in the particle-size control section.
GEOGRAPHIC SETTING: Sevenoaks soils are on low stream terraces at elevations of 1,000 to 1,500 feet. Slopes are 0 to 3 percent. The soils formed in alluvium derived from mixed rock sources and mixed with various amounts of pumice sand. The mean annual temperature is 50 to 54 degrees F. The mean annual precipitation is 18 to 25 inches. The frost-free period is 150 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Camas, Evans, Foehlin, Newberg, and Takilma soils. Camas soils are sandy-skeletal and subject to flooding. Evans and Newberg soils are coarse-loamy and subject to flooding. Foehlin soils are fine-loamy and have an argillic horizon. Takilma soils are loamy-skeletal.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow runoff; rapid permeability.
USE AND VEGETATION: Sevenoaks soils are used for cultivated crops, hay, pasture, and recreation. Native vegetation is common snowberry, serviceberry, Idaho fescue, and poison oak.
DISTRIBUTION AND EXTENT: Interior valleys of southwestern Oregon. The soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Jackson County Area, Oregon, 1988.
REMARKS: The classification was changed in 2006 from a sandy, mixed, mesic Entic Haploxerolls to the Psammentic Haploxerools family using the 9th edition of keys to taxonomy. Competing series were not checked at that time. Although the series contains appreciable amounts of volcanic ash and pumice, there isnt enough to change the classification.
Diagnostic horizons and features:
Mollic epipedon - from the surface to a depth of 14 inches; (Ap1 and Ap2).