LOCATION PASTURECREEK ORTentative Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Andic Eutrudepts
TYPICAL PEDON: Pasturecreek gravelly ashy silt loam - forested, on a 55 percent westfacing slope at an elevation of 5,700 feet. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 0.5 inches; slightly decomposed needles
Oe--0.5 to 1 inch; moderately decomposed forest litter
A--1 to 8 inches; very dark grayish brown (10YR 3/2) gravelly ashy silt loam, brown (10YR 5/3) dry; weak fine and medium granular structure; soft, very friable, nonsticky and nonplastic; many fine and few medium and coarse roots; many fine and medium irregular pores; 20 percent gravel; slightly acid (pH 6.1); clear wavy boundary. (0 to 7 inches thick)
Bw--8 to 14 inches; dark yellowish brown (10YR 4/4) gravelly ashy silt loam, light yellowish brown (10YR 6/4) dry; moderate fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and few medium roots; few fine and medium irregular and few fine tubular pores; 30 percent gravel; slightly acid (pH 6.1); clear wavy boundary. (6 to 11 inches thick)
2Eb--14 to 25 inches; dark grayish brown (2.5Y 4/2) very gravelly sandy loam, light brownish gray (2.5Y 6/2) dry; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few fine and medium roots; common fine and medium irregular and few fine tubular pores; 50 percent gravel and 5 percent cobbles; slightly acid (pH 6.1); gradual smooth boundary. (0 to 19 inches thick)
2Bwb--25 to 43 inches; dark grayish brown (2.5Y 4/2) extremely gravelly sandy loam, light brownish gray (2.5Y 6/2) dry; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common fine and few medium roots; many fine, common medium and few coarse irregular pores; 50 percent gravel, 15 percent cobbles, and 5 percent stones; slightly acid (pH 6.1); gradual smooth boundary. (15 to 27 inches thick)
2BCb--43 to 61 inches; dark grayish brown (2.5Y 4/2) extremely gravelly sandy loam, light brownish gray (2.5Y 6/2) dry; single grain; loose, nonsticky and nonplastic; few fine and medium roots; common fine and medium and few coarse irregular pores; 60 percent gravel and 10 percent cobbles; slightly acid (pH 6.1).
TYPE LOCATION: Baker County, Oregon
Section 12 (SE 1/4, SW 1/4, NE 1/4), T. 9 S., R. 36 E.
Latitude: 44 degrees, 47 minutes, 47 seconds North
Longitude: 118 degrees, 14 minutes, 30 seconds West
UTM coordinates: zone 11; northing: 4,960,865; easting: 401,789; NAD27
USGS Quadrangle: Bourne
RANGE IN CHARACTERISTICS:
Soil Temperature: frigid regime
Mean Annual Soil Temperature: 38 to 43 degrees F
Mean Summer Soil Temperature: 47 to 51 degrees F
Mean Winter Soil Temperature: 32 to 36 degrees F
Soil Moisture: udic regime; dry 30 to 45 consecutive days in summer
Particle-size Control Section: from 10 to 40 inches below the mineral soil surface
clay content, average: 7 to 16 percent
rock fragment content, average: 35 to 75 percent
Diagnostic Horizons and Features:
andic subgroup properties: upper boundary at the mineral surface; 7 to 13 inches thick
Al+1/2Fe (ammonium oxalate): 1.0 to 2.4 percent
bulk density: 0.75 to 1.00 g/cc
P retention: 50 to 80 percent
0.02-2.0 mm fraction: 40 to 60 percent of fine earth
glass content in the 0.02-2.0mm fraction: 45 to 65 percent
water content 1500 kPa water (air dried): 10 to 12 percent
cambic horizon, upper: 6 to 10 inches thick
cambic horizon, buried: 11 to 18 inches thick
lithic contact, depth below mineral soil surface: 40 to 80 inches
A horizon:
color, moist: 7.5YR 3/2, 3/4; 10YR 3/2, 3/3, 3/4
color, dry: 7.5YR 5/2, 4/3, 5/3, 5/4; 10YR 4/4, 5/3, 5/4, 6/2, 6/3
texture: ASHY-SIL, GR-ASHY-SIL
clay content: 5 to 15 percent
rock fragment content: 0 to 30 percent gravel
reaction: slightly acid to neutral; pH: 6.1 to 7.3
Bw horizon:
color, moist: 7.5YR 4/3, 4/4, 4/6; 10YR 4/4, 5/3
color, dry: 7.5YR 5/3, 5/4, 6/4; 10YR 6/3, 6/4, 7/3
texture: ASHY-SIL, GR-ASHY-SIL
clay content: 4 to 8 percent
rock fragment content: 5 to 30 percent gravel
reaction: slightly acid to neutral; pH: 6.1 to 7.3
2Eb horizon:
color, moist: 10YR 4/2, 4/4, 5/2; 2.5Y 4/2
color, dry: 10YR 5/4, 7/2; 2.5Y 6/2, 7/2
texture: GRV-SL, GRV-L
clay content: 8 to 15 percent
rock fragment content: 40 to 60 percent total
gravel: 30 to 50 percent
cobbles: 0 to 15 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
2Bwb horizon:
color, moist: 10YR 4/3, 5/3, 5/6; 2.5Y 4/2, 5/2
color, dry: 10YR 6/2, 6/6; 2.5Y 6/2, 7/2, 8/2
texture: GRX-SL, GRV-SL, GRX-L
clay content: 9 to 17 percent
rock fragment content: 45 to 80 percent total
gravel: 35 to 55 percent
cobbles: 0 to 20 percent
stones: 0 to 20 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
2BCb horizon:
color, moist: 10YR 4/3, 5/3, 5/6; 2.5Y 4/2; 5Y 5/2
color, dry: 10YR 6/4; 2.5Y 6/2; 5Y 6/2
texture: GRX-SL, STX-SL, GRX-L
clay content: 10 to 17 percent
rock fragment content: 60 to 85 percent
gravel: 35 to 65 percent
cobbles: 0 to 15 percent
stones: 0 to 25 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
COMPETING SERIES: There are no competing series in the isotic mineralogy family.
The following series are similar but in a mixed mineralogy class:
Bendahl - very deep; formed in calcareous till or colluvium; has horizons with secondary carbonate accumulation (2Bk);
Courville - very deep; formed in non-calcareous till; has 2E/Bw and 2Bw/E horizons with two distinct parts
Mitten - very deep; formed in volcanic ash over colluvium from argillite or quartzite; has 2E and Bw horizon with lamellae
GEOGRAPHIC SETTING:
Landform: backslopes of mountains
Slope gradient: 30 to 90 percent
Parent material: volcanic ash over colluvium and residuum
Lithology: argillite, metavolcanic rocks or rhyolite
Elevation: 4,800 to 6,200 feet
Climate: cold, wet winters and cool, moist summers
Mean annual precipitation: 25 to 40 inches
Mean annual air temperature: 35 to 41 degrees F
Frostfree period: 25 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Analulu: on convex backslopes and ridges, moderately deep to bedrock with a minor influence of volcanic ash under Douglas-fir, ponderosa pine or grand fir forest
Gutridge: on north-aspect backslopes and footslopes; moderately deep to bedrock with a thick ash mantle under moist (udic) grand fir forest
McWillar: on backslopes; deep to argillite bedrock; thick volcanic ash mantle over loamy-skeletal argillic horizon; under grand fir, birchleaf spiraea, pussytoes, and pinegrass
Threecent: on gently sloping benches and depositional backslopes; moderately deep to argillite bedrock; ash mantle is 14 to 18 inches thick over loamy-skeletal colluvium; under grand fir, big huckleberry, longtube twinflower and common princes pine
DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderately rapid
USE AND VEGETATION:
Use: watershed, wildlife habitat, timber production, livestock grazing and recreation
Potential native vegetation: grand fir, lodgepole pine, western larch, Douglas-fir, ponderosa pine, longtube twinflower, big huckleberry, scoulars willow, Oregon boxwood, grouse whortleberry, prince's pine, birchleaf spiraea, sidebells pyrola, roundleaf violet, rattlesnake plantain, heartleaf arnica, pinegrass and northwest sedge
Plant Association: ABGR/LIBOL2 (grand fir/ longtube twinflower); may include ABGR/VAME (grand fir/big huckleberry) or ABGR/VASC (grand fir/ grouse whortleberry).
DISTRIBUTION AND EXTENT:
Distribution: MLRA 43c; Blue Mountains in northeastern Oregon
Extent: small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Wallowa-Whitman National Forest, Oregon 2008. The name is from a stream.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon: 1 to 8 inches; A horizon
cambic horizon: upper: 8 to 14 inches; Bw horizon
eluvial layer, buried: 14 to 25 inches; 2Eb horizon
cambic horizon, buried: 25 to 43 inches; 2Bwb horizon
andic subgroup properties (mixed ash layer): 1 to 14 inches; A, Bw horizons
particle-size control section: 11 to 41 inches; Bw, 2Eb, 2Bwb horizons