LOCATION SCOURED CAEstablished Series
The Scoured series consists of moderately deep, well drained soils that formed in tephra over colluvium and/or residuum from volcanic rocks. Scoured soils are on glacially scoured ridges and glacial headlands in the Southern Cascade mountains. Slopes range from 2 to 90 percent. The mean annual precipitation is about 49 inches (1245 mm) and the mean annual temperature is about 41 degrees F (5 degrees C).
TAXONOMIC CLASS: Medial-skeletal over fragmental or cindery, amorphic over isotic, frigid Humic Haploxerands
TYPICAL PEDON: Scoured very bouldery medial loamy sand, on an east-northeast facing (60 degrees) slope of 25 percent, under a cover of pinemat manzanita, western white pine, California red fir, lodgepole pine, blue wildrye, dryland sedge, stipa, squirreltail, and mountain monardella, at an elevation of 6823 feet, (2080 m). When described on 10/4/06, the soil was moist to a depth of 1.5 inches (4 cm), and dry below that to a depth of 30 inches (76 cm). (Colors are for dry soil unless otherwise noted).
Oi--0 to 1 inches (0 to 2 cm); slightly decomposed needles, leaves, twigs and bark litter; abrupt smooth boundary. (0 to 1 inch (0 to 2 cm) thick)
A--1 to 4 inches (2 to 10 cm); dark grayish brown (10YR 4/2) very bouldery medial loamy sand, very dark gray (7.5YR 3/1) moist; 2 percent clay; weak fine and medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; many very fine and common fine roots; common very fine and fine tubular and irregular pores; 7 percent subangular fine gravel, 10 percent subangular medium and coarse gravel, 10 percent subangular cobbles, 10 percent subangular stones and 15 percent subangular boulders; moderately acid, pH 5.8 by pH meter 1:1 water; NaF pH 11.2; abrupt smooth boundary. (3 to 8.5 inches (8 to 21 cm) thick)
AB--4 to 10 inches (10 to 25 cm); dark grayish brown (10YR 4/2) very bouldery medial sandy loam, very dark grayish brown (10YR 3/2) moist; 2 percent clay; weak fine and medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine and fine and few medium and coarse roots; common fine and medium irregular and tubular pores; 14 percent subangular fine gravel, 10 percent subangular medium and coarse gravel, 10 percent subangular cobbles, 10 percent subangular stones, and 10 percent subangular boulders; moderately acid, pH 6.0 by pH meter 1:1 water; NaF pH 11.6; clear smooth boundary. (0 to 6 inches (0 to 15 cm) thick)
2Bw--10 to 17 inches (25 to 42 cm); brown (10YR 4/3) very bouldery medial fine sandy loam, dark brown (7.5YR 3/2) moist; 2 percent clay; weak fine and medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine and fine and few medium roots; common fine and medium tubular and irregular pores; 10 percent subangular fine gravel, 13 percent subangular medium and coarse gravel, 10 percent subangular cobbles, 10 percent subangular stones, and 15 percent subangular boulders; moderately acid, pH 6.0 by pH meter 1:1 water; NaF pH 11.7; abrupt wavy boundary. (6.5 to 11 inches (17 to 27 cm) thick)
2C--17 to 30 inches (42 to 76 cm); boulders, 2 percent clay; massive; few very fine and fine roots; 20 percent subangular medium and coarse gravel, 25 percent subangular cobbles, 25 percent subangular stones, and 25 percent subangular boulders; slightly acid, pH 6.1 by pH meter 1:1 water; NaF pH 11.7; clear wavy boundary. (0 to 13.5 inches (0 to 34 cm) thick)
2R--30 to 39 inches (76 to 100 cm); lithic bedrock; massive; indurated, few very fine and fine roots.
TYPE LOCATION: Plumas County, California, about 0.96 miles south-southeast of the new Juniper Lake ranger station, 700 feet north and 2,500 feet east of the southwest corner of sec 23, T. 30 N, R. 6 E, 40 degrees, 26 minutes, 23 seconds north latitude and 121 degrees, 16 minutes, 48 seconds west longitude, NAD83; USGS Quad: Mount Harkness, California.
RANGE IN CHARACTERISTICS:
Depth to restrictive feature: Lithic contact 20 to 40 inches (51 to 102 cm).
Mean annual soil temperature: 43 to 45 degrees F (6 to 7 degrees C).
Soil moisture control section is dry: July to October (about 90 days).
Particle-size control section (weighted average): 1 to 6 percent clay, and 42 to 76 percent rock fragments.
Surface fragments: 3 to 40 percent gravel, 3 to 10 percent cobbles, 3 to 10 percent stones, and 0 to 10 percent boulders.
Some pedons have a B/R, or 2BC horizon above the lithic contact.
A horizon:
Color dry: 10YR 4/2, 5/2, 5/3, 2.5Y 5/3
Color moist: 7.5YR 3/1, 10YR 3/1, 3/2
Texture: gravelly medial loamy sand, very stony medial loamy sand, very stony medial sandy loam, very bouldery medial loamy sand
Clay content: 1 to 3 percent
Rock fragments: 1 to 8 percent fine gravel, 2 to 12 percent medium and coarse gravel, 3 to 20 percent total gravel, 0 to 10 percent cobbles, 0 to 45 percent stones, 0 to 15 percent boulders, 20 to 56 percent total rock fragments
Organic matter: 13.5 to 18 percent
Base saturation by ammonium acetate: 20 to 45 percent
Acid oxalate extractable Al plus 1/2 Fe: 1.3 to 2.0
P retention: 65 to 85 percent
Glass content: 14 to 20 percent
NaF pH: 10.4 to 11.2
Soil reaction: moderately acid or slightly acid
AB horizon:
Color dry: 10YR 4/2, 5/4
Color moist: 10YR 3/2, 4/3
Texture: very gravelly medial sandy loam, very stony medial fine sandy loam, very bouldery medial sandy loam
Clay content: 1 to 5 percent
Rock fragments: 6 to 14 percent fine gravel, 10 to 15 percent medium and coarse gravel, 19 to 24 percent total gravel, 5 to 10 percent cobbles, 10 to 30 percent stones, 0 to 15 percent boulders, 54 percent total rock fragments
Organic matter: 12.0 to 16.0 percent
Base saturation by ammonium acetate: 5 to 15 percent
Acid oxalate extractable Al plus 1/2 Fe: 1.90 to 3.20
P retention: 85 to 100 percent
Glass content: 14 to 20 percent
NaF pH: 11.0 to 11.6
Soil reaction: moderately acid or slightly acid
2Bw horizon:
Color dry: 10YR 4/3, 5/3, 5/4, 6/4
Color moist: 7.5YR 3/2, 10YR 4/2, 3/3, 4/3
Texture: very gravelly medial fine sandy loam, extremely stony medial fine sandy loam, very bouldery medial fine sandy loam, very stony medial fine sandy loam, gravelly medial very fine sandy loam
Clay content: 1 to 8 percent
Rock fragments: 1 to 14 percent fine gravel, 2 to 23 percent medium and coarse gravel, 3 to 34 percent total gravel, 0 to 10 percent cobbles, 0 to 80 percent stones, 0 to 15 percent boulders, 33 to 83 percent total rock fragments
Organic matter: 12.0 to 16.5 percent
Base saturation by ammonium acetate: 4 to 12 percent
Acid oxalate extractable Al plus 1/2 Fe: 3.00 to 5.00
P retention: 90 to 100 percent
Glass content: 8 to 15 percent
NaF pH: 11.0 to 11.7
Soil reaction: slightly acid or moderately acid
2C horizon:
Color dry: 10YR 4/3, 5/3, 5/4, 6/4
Color moist: 7.5YR 3/2, 10YR 4/2, 3/3, 4/3
Texture: boulders, stones, cobbles
Clay content: 1 to 3 percent
Rock fragments: 0 to 20 percent fine gravel, 20 to 35 percent medium and coarse gravel, 20 ro 40 percent total gravel, 20 to 35 percent cobbles, 20 to 85 percent stones, 20 to 60 percent boulders, 90 to 98 percent total rock fragments
Organic matter: 1 to 4 percent
Base saturation by ammonium acetate: 4 to 12 percent
Acid oxalate extractable Al plus 1/2 Fe: 1.5 to 3
P retention: 90 to 100 percent
Glass content: 2 to 5 percent
NaF pH: 11.0 to 11.7
Soil reaction: slightly acid or moderately acid
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Scoured soils are on glacially scoured ridges and headlands in the Southern Cascade mountains. Slopes are 2 to 90 percent. These soils formed in tephra over colluvium and/or residuum from volcanic rocks. Elevation is 5494 to 8190 feet (1675 to 2497 m). Mean annual precipitation is 33 to 109 inches (838 to 2769 mm). The mean annual temperature is 39 to 44 degrees F (4 to 6 degrees C). Frost free season is 60 to 85 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Juniperlake and Ashbutte soils. The Juniperlake soils are deep to dense till, and are on ground moraines. The Ashbutte soils are very deep and are on cinder cones.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; saturated hydraulic conductivity is high to very high in the A horizon, high in the AB and 2C horizons, and moderately high to high in the 2Bw horizon.
USE AND VEGETATION: This soil is used for wildlife habitat, recreation, ecosystem management and watershed. Vegetation is pinemat manzanita, western white pine, California red fir, lodgepole pine, blue wildrye, dryland sedge, stipa, squirreltail, and mountain monardella.
DISTRIBUTION AND EXTENT: The soils are inextensive and are mapped in MLRA: 22B Southern Cascade Mountains
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Plumas County, California. Source of name is coined and connotes the glacial scouring process that stripped the land down to bedrock and formed the landforms upon which this soil exists.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon: 1 to 17 inches, (2 to 42 cm)
Andic soil properties: 1 to 17 inches, (2 to 42 cm)
Lithic contact: 30 inches, (76 cm)
Particle-size control section: 1 to 30 inches (2 to 76 cm)
Soil moisture control section: 18.5 to 30 inches (47.5 to 76 cm)
ADDITIONAL DATA:
Characterization data from lab pedon number 07N0137 NSSL, Lincoln, NE. NASIS User Pedon ID in Davis, MLRA Office: 789180.