LOCATION PEARSOLL OREstablished Series
TAXONOMIC CLASS: Clayey-skeletal, magnesic, mesic Lithic Dystroxerepts
TYPICAL PEDON: Pearsoll extremely stony clay loam, range. (Colors are for moist soil unless otherwise noted.)
A--0 to 5 inches; dark reddish brown (5YR 3/3) extremely stony clay loam, reddish brown (5YR 4/4) dry; moderate fine and very fine subangular blocky structure; very hard, friable, sticky and plastic; common fine and very fine and few medium roots; common irregular pores; 5 percent of surface covered with stones; 40 percent angular gravel and 20 percent cobbles; slightly acid (pH 6.4); clear wavy boundary. (2 to 6 inches thick)
Bw--5 to 14 inches; dark reddish brown (5YR 3/4) extremely cobbly clay, reddish brown (5YR 4/4) crushed, reddish brown (5YR 4/4) dry; weak medium subangular blocky structure; very hard, firm, very sticky and very plastic; few fine and very fine roots; common fine and very fine tubular pores; 65 percent cobbles and 15 percent gravel; neutral (pH 6.6); abrupt wavy boundary. (7 to 15 inches thick)
R--14 inches; fractured serpentinite.
TYPE LOCATION: Josephine County, Oregon; 1/2 mile south of Waldo (site) and 50 feet above the Waldo Lookout road; about 1,400 feet north and 600 feet west of the southeast corner of sec. 28, T. 40 S., R. 8 W., Willamette Meridian.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry throughout the control section for 60 to 100 consecutive days during the summer. Depth to a lithic contact ranges from 10 to 20 inches. The mean annual soil temperature ranges from 47 to 57 degrees F. Rock fragment in the solum ranges from 20 to 60 percent cobbles and 10 to 25 percent gravel with total averaging 35 to 70 percent. Stone-size rock fragments cover 3 to 15 percent of the surface. Small boulders occur in some areas. Soil reaction is slightly acid to neutral.
The A horizon has hue of 5YR or 7.5YR, value of 3 or 4 dry, and chroma of 2 or 3 moist and 3 or 4 dry. It is extremely stony clay loam or very cobbly clay loam with 30 to 40 percent clay.
The Bw horizon has hue of 7.5YR, 5YR or 2.5YR, value of 3 to 5 moist, 4 or 5 dry, and chroma of 4 through 6 moist and dry. It is very cobbly clay or extremely cobbly clay with 40 to 60 percent clay. It has weak to strong very fine to medium subangular blocky or angular blocky structure.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: The Pearsoll soils are on broad ridgetops and side slopes of mountains. Elevations are 600 to 4,100 feet. Slopes range from 3 to 90 percent. The soils formed in cobbly fine textured colluvium and residuum weathered from serpentinite or peridotite. The summers are hot and dry and winters are cool and moist. The mean annual temperature is 45 to 56 degrees F. The mean annual precipitation is typically 30 to 60 inches but may range to 100 inches in the interior mountains of Curry County, Oregon. The frost-free period is 100 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brockman, Cornutt, Dubakella, Eightlar, and McMullin soils. Brockman soils are on alluvial fans, are deep and have less than 35 percent fragments of rock. Cornutt soils are more than 40 inches deep and have an argillic horizon. Dubakella soils are 20 to 40 inches deep to bedrock. Eightlar soils are more than 60 inches deep. McMullin soils have less than 35 percent rock fragments and have mixed mineralogy. All soils except Brockman are on ridgetops and side slopes of mountains.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; slow permeability.
USE AND VEGETATION: Wildlife habitat and grazing. The native vegetation dominantly is sheep fescue, lomatium, ceanothus, Jeffrey pine, and incense cedar. In Curry County, Oregon, the overstory also includes tanoak and California black oak.
DISTRIBUTION AND EXTENT: Mountainous areas of southwestern Oregon and northern California; MLRA 5. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Josephine County, Oregon, 1979.
REMARKS: Formerly classified as clayey-skeletal, magnesic, mesic Lithic Xerochrepts, competing series not updated at the time of reclassification.
Diagnostic horizons and features recognized include:
Ochric epipedon
Cambic horizon - from 5 to 14 inches (Bw horizon)
Lithic feature - hard bedrock at 14 inches.
Particle-size control section - from 0 to 14 inches (A and Bw horizons)