LOCATION POWDERRIVER ORTentative Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Lithic Haploxerepts
TYPICAL PEDON: Powderriver gravelly ashy sandy loam - forested, on a 40 percent southwest slope at 4,790 feet elevation. (Colors are for moist soil unless otherwise noted. Soil textures are apparent field textures.)
Oi--0 to 0.5 inch; slightly decomposed needles and leaves.
A--0.5 to 4 inches; very dark grayish brown (10YR 3/2) gravelly ashy sandy loam, brown (10YR 5/3) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine roots; common fine irregular pores; 20 percent gravel and 5 percent cobbles; moderately acid (pH 6.0); gradual smooth boundary. (3 to 7 inches thick)
Bw--4 to 10 inches; dark yellowish brown (10YR 3/4) very gravelly ashy coarse sandy loam, light yellowish brown (10YR 6/4) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many fine and few medium roots; common fine irregular pores; 30 percent gravel and 10 percent cobbles; moderately acid (pH 6.0); gradual smooth boundary. (6 to 10 inches thick)
C--10 to 15 inches; brown (10YR 5/3) very gravelly ashy coarse sandy loam, light yellowish brown (10YR 6/4) dry; single grain; loose, nonsticky and nonplastic; common fine and few medium roots; common fine irregular pores; 50 percent gravel and 5 percent cobbles; moderately acid (pH 6.0); clear irregular boundary. (0 to 12 inches thick)
R--15 inches; granite bedrock
TYPE LOCATION: Baker County, Oregon
Section 1 (NE , SW , SE ), T. 7 S., R. 37 E.
Latitude: 44 degrees, 58 minutes, 50 seconds; North
Longitude: 118 degrees, 07 minutes, 18 seconds; West
UTM coordinates: Zone 11; 4,981,185 northing; 411,563 easting; NAD 27
USGS Quadrangle: Rock Creek
RANGE IN CHARACTERISTICS:
Soil Temperature: frigid regime
Mean Annual Soil Temperature: 40 to 46 degrees F
Mean Summer Soil Temperature: 49 to 58 degrees F
Mean Winter Soil Temperature: 32 to 37 degrees F
Soil Moisture: xeric regime; dry 60 to 75 consecutive days in summer
Particle-size Control Section: 10 inches below the mineral soil surface to lithic contact
clay content, average: 2 to 8 percent
rock fragment content, average: 40 to 55 percent
Diagnostic Horizons and Features:
vitrandic subgroup properties: upper boundary at the mineral surface; 12 to 19 inches thick
Al+1/2Fe (ammonium oxalate): 0.3 to 0.9 percent
P retention: 20 to 40 percent
glass content in the 0.02-2.0mm fraction: 5 to 15 percent
cambic horizon: 6 to 10 inches thick
lithic contact, depth below mineral soil surface: 12 to 20 inches
A horizon:
color, moist: 7.5YR 3/2; 10YR 2/2, 3/2
color, dry: 10YR 4/4, 5/3
texture: GR-ASHY-SL, GRV-ASHY-SL
clay content: 4 to 8 percent
rock fragments: 15 to 40 percent
gravel: 10 to 25 percent
cobbles: 0 to 10 percent
stones: 0 to 5 percent
reaction: moderately acid to slightly acid; pH: 5.6 to 6.3
Bw horizon:
color, moist: 7.5YR 3/4; 10YR 3/4, 5/3
color, dry: 10YR 4/4, 6/4
texture: GRV-ASHY-COSL, GRV-ASHY-SL, GR-ASHY-SL
clay content: 4 to 8 percent
rock fragments: 15 to 55 percent
gravel: 15 to 35 percent
cobbles: 0 to 10 percent
stones: 0 to 5 percent
reaction: moderately acid; pH: 5.6 to 6.0
C horizon:
color, moist: 7.5YR 4/6; 10YR 5/3, 5/4
color, dry: 7.5YR 5/6: 10YR 6/4
texture: GRV-ASHY-COSL, GRV-ASHY-LS, GRV-ASHY-SL
clay content: 2 to 5 percent
rock fragments: 35 to 55 percent
gravel: 35 to 55 percent
cobbles: 0 to 15 percent
reaction: moderately acid; pH: 5.6 to 6.0
COMPETING SERIES:
Vogel: shallow (10 to 20 inches) to a lithic contact (argillite); formed in metasedimentary residuum mixed with a small amount of volcanic ash; slightly acid or neutral throughout; rock fragments are angular to subangular
GEOGRAPHIC SETTING:
Landform: backslopes of mountains
Slope gradient: 15 to 60 percent
Parent material: colluvium over residuum mixed with a small amount of volcanic ash
Lithology: granite
Elevation: 4,000 to 6,200 feet
Climate: cold, wet winters and warm, dry summers
Mean annual precipitation: 20 to 45 inches
Mean annual air temperature: 36 to 43 degrees F
Frostfree period: 25 to 80 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Coyotebluff: on steep backslopes; deep, mollic epipedon, loamy-skeletal, and mixed ash mantle under grand fir, Douglas-fir, Rocky Mountain maple, mallow ninebark, pinegrass and elk sedge
Endcreek: on gently sloping benches and toeslopes; thick ash mantle over buried loamy-skeletal colluvium; under grand fir, Douglas-fir, grouse wortleberry and mountain brome
Golfer: on steep, convex backslopes; moderately deep, mollic epipedon, loamy-skeletal and minor amount of volcanic ash; under Douglas-fir, ponderosa pine, pinegrass, mallow ninebark and elk sedge
Piutespring: on steep backslopes; moderately deep to lithic contact; thin volcanic ash mantle; under grand fir, Douglas-fir, ponderosa pine, birchleaf spiraea, pinegrass and elk sedge
Raggedrock: on planer lower to middle backslopes; deep to paralithic, soft granitic rock; thick ash mantle over very gravelly buried soil; under grand fir, Douglas-fir, big huckleberry, grouse whortleberry and mountain brome
Roundmeadow: on convex backslopes; moderately deep, thin ash mantle over coarse-loamy colluvium; under grand fir, western larch, lodgepole pine, big huckleberry and pinegrass
Sixdollar: on north slopes; deep soil with mollic epipedon and thick volcanic ash mantle; under Douglas-fir, ponderosa pine and grand fir with birchleaf spiraea, common snowberry and pinegrass
Spartabutte: on backslopes, moderately deep; mollic epipedon, argillic horizon and a minor influence of volcanic ash, under Douglas-fir, ponderosa pine and grand fir with common snowberry, birchleaf spiraea, mountain snowberry, elk sedge and pinegrass
Warfield: on moraines; very deep with volcanic ash mixed in upper part of till; under grand fir, Douglas-fir, western larch, Scoular's willow, birchleaf spiraea, and pinegrass
DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderately rapid
USE AND VEGETATION:
Use: watershed, wildlife habitat, timber production, livestock grazing and recreation.
Native vegetation: grand fir, Douglas-fir, ponderosa pine, lodgepole pine, Scoular's willow, birchleaf spiraea, Wyeth's creamy buckwheat, common chokecherry, Oregon grape, Rocky Mountain maple, common yarrow, white flowered hawkweed, sandwort, aster, lupine, elk sedge and bluebunch wheatgrass
Plant Association: PSME/CARU (Douglas-fir/pinegrass); may include: ABGR/ACGL (grand fir/Rocky Mountain maple), ABGR/CARU (grand fir/pinegrass), PSME/SPBE (Douglas-fir/birchleaf spiraea) and PIPO/CAGE (ponderosa pine/elk sedge).
DISTRIBUTION AND EXTENT:
Distribution: MLRA 43c; Blue Mountains of northeastern Oregon
Extent: small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Wallowa-Whitman National Forest, 2008. The name is from a river with headwaters in the Elkhorn Mountains.
REMARKS: Diagnostic horizons and features recognized in this pedon (88-0175) are:
ochric epipedon: 0.5 to 4 inches; A horizon
cambic horizon: 4 to 10 inches; Bw horizon
vitrandic subgroup properties (ash influenced layer): 0.5 to 15 inches; A, Bw, C horizons
particle-size control section: 10 to 15 inches; C horizon
lithic contact: 15 inches; top of the R horizon
Some pedons have 4 to 6 inches of weathered granite (grus) above the lithic contact.