LOCATION BIGWALL ORTentative Series
TAXONOMIC CLASS: Ashy, amorphic, frigid Typic Vitrixerands
TYPICAL PEDON: Bigwall ashy silt loam - woodland, on a 14 percent, south-facing slope at an elevation of 4,760 feet. (Colors are for moist soil unless otherwise noted. Soil textures are apparent field textures.)
Oi--0 to 1 inches; needles, twigs, branches.
A--1 to 6 inches; dark brown (10YR 3/3) ashy silt loam, pale brown (10YR 6/3) dry; weak medium subangular blocky structure parting to weak fine and very fine subangular blocky; soft, very friable, nonsticky and nonplastic; weakly smeary; many very fine, fine and few medium roots; common very fine and few fine irregular pores; slightly acid (pH 6.2); clear wavy boundary. (4 to 8 inches thick)
Bw--6 to 25 inches; brown (10YR 4/3) ashy silt loam, very pale brown (10YR 7/3) dry; weak medium, subangular blocky structure parting to weak fine and very fine subangular blocky; soft, very friable, nonsticky and nonplastic; weakly smeary; common very fine, fine, medium and coarse roots; few fine tubular pores; slightly acid (pH 6.2); clear wavy boundary. (13 to 26 inches thick)
BC--25 to 45 inches; light gray (10YR 7/2) ashy sandy loam, very pale brown (10YR 8/2) dry; massive; soft, friable, nonsticky and nonplastic; weakly smeary; few very fine and fine roots; few very fine and fine tubular pores; slightly acid (pH 6.5); gradual smooth boundary. (15 to 23 inches thick)
C--45 to 61 inches; light gray (10YR 7/2) ashy sandy loam, white (10YR 8/1) dry; massive; soft, friable, nonsticky and nonplastic; weakly smeary; few very fine and few fine roots; few fine tubular pores; neutral (pH 7.0)
TYPE LOCATION: Grant County, Oregon
Section 10 (NE1/4, NE1/4, NE1/4), T. 5 S., R. 35 E.
Latitude: 44 degrees, 53 minutes, 28 seconds N.
Longitude: 118 degrees, 28 minutes, 16 seconds W.
UTM Coordinates: Zone: 11; Northing: 4,971,920; Easting: 383,830
USGS Quadrangle: Trout Meadows
RANGE IN CHARACTERISTICS:
Soil Temperature: frigid regime
Mean Annual Soil Temperature: 43 to 49 degrees F
Mean Summer Soil Temperature: 51 to 60 degrees F
Mean Winter Soil Temperature: 34 to 39 degrees F
Soil Moisture: xeric regime, dry 60 to 90 days in summer
Particle-size Control Section: the mineral surface to 40 inches below the mineral surface
Clay content (wt. avg.): 3 to 8 percent
Rock fragment content: 0 percent
Diagnostic Horizons and Features:
andic soil properties (amorphic part): from the mineral surface, 21 to 30 inches thick
Al+1/2Fe(aox): 1.0 to 2.5 percent
bulk density: 0.65 to 1.0 g/cc
P retention: 40 to 90 percent
0.02-2.0 mm fraction: 40 to 60 percent of fine earth
glass content in the 0.02-2.0 mm fraction: 60 to 90 percent
water content at 1500 kPa (air dried): 5 to 12 percent
8Si + 2Fe (aox): 5 to 12 percent
8Si - 2Fe (aox): 4 to 8 percent
andic soil properties (glassy part): to 61 inches or more
Al+1/2Fe(aox): 0.4 to 1.5 percent
bulk density: 0.65 to 1.2 g/cc
P retention: 25 to 65 percent
0.02-2.0 mm fraction: 40 to 60 percent of fine earth
glass content in the 0.02-2.0 mm fraction: 60 to 90 percent
water content at 1500 kPa (air dried): 5 to 10 percent
8Si + 2Fe (aox): 2 to 5 percent
8Si - 2Fe (aox): -2 to 0 percent
ochric epipedon: 5 4 to 24 8 inches thick
cambic horizon: 11 28 to 43 49 inches thick
Major Horizons:
A horizon:
color, moist: 10YR 3/2, 3/3
color, dry: 10YR 5/3, 6/2, 6/3, 6/4
texture: ASHY-SIL
clay content: 3 to 10 percent
rock fragment content: 0 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
organic carbon: 1 to 5 percent
Bw horizon:
color, moist: 10YR 3/3, 4/3
color, dry: 10YR 6/2, 7/3
texture: ASHY-SIL
clay content: 2 to 8 percent
rock fragment content: 0 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
organic carbon: 0.6 to 1.0 percent
BC horizon:
color, moist: 10YR 5/2, 5/3, 6/3, 7/2
color, dry: 10YR 7/3, 8/1, 8/2
texture: ASHY-SIL, ASHY-SL
clay content: 2 to 5 percent
rock fragment content: 0 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
C Horizon:
color, moist: 10YR 6/3, 7/2, 7/3
color, dry: 10YR 7/3, 8/1, 8/2
texture: ASHY-SIL, ASHY-SL
clay content: 1 to 3 percent
rock fragment content: 0 percent
reaction: neutral; pH: 6.6 to 7.3
COMPETING SERIES:
This is the
Tahkeal series. Soils with a similar classification include the
Chiwawa,
Dekkas, Powlander,
Slakish (T),
Thow and
Vinegar (T) series.
Tahkeal - dry for 45 to 60 consecutive days following the summer solstice; depth to ashy-skeletal mudflow deposits (2Bw) is 25 to 40 inches; pscs has 5 to 30 volcanic glass
Chiwawa soils - depth to sandy-skeletal (2C) horizon is 40 to 60 inches; pscs has 30 to 60 percent volcanic glass, 15 to 35 percent paragravel (pumice), and glassy mineralogy
Dekkas soils - depth to secondary silica accumulation (Bq) horizon is 34 to 53 inches; pscs has 5 to 15 percent volcanic glass and mixed mineralogy
Polander soils - depth to a paralithic contact (tuffaceous bedrock) is 40 to 60 inches; pscs has 40 to 70 percent volcanic glass, 10 to 18 percent clay, and glassy mineralogy
Slakish soils - dry for 45 to 60 consecutive days following the summer solstice; depth to a paralithic contact (weathered basalt) is 40 to 60 inches; pscs has 5 to 30 percent volcanic glass and mixed mineralogy
Thow soils - depth to loamy-skeletal (2C) horizon is 40 to 80 inches; pscs has 5 to 35 percent paragravel (pumice), 30 to 60 percent volcanic glass, and glassy mineralogy
Vinegar soils - pscs has 30 to 60 percent volcanic glass, 5 to 30 percent paragravel (pumice), and glassy mineralogy
GEOGRAPHIC SETTING:
Landform: terraces on mountain valley floors
Slope gradient: 0 to 15 percent
Parent material: volcaniclastic volcanic ash
Lithology: Mazama ash over alluvium from argillite, basalt or metavolcanic rocks
Elevations: 2,800 to 4,800 feet
Climate: cold, wet winters and warm, dry summers
Mean annual precipitation: 17 to 37 inches
Mean annual air temperature: 41 to 47 degrees F
Frost-free period: 40 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Melloe (T): occur on terraces and flood plains of valley floors; >60 inches to bedrock; has mollic epipedon; no ash recognized; >35 percent rock fragments in pscs
Dardry (T): occur on terraces of mountain valley floors; >60 inches to bedrock; has mollic epipedon; no ash recognized; >35 percent rock fragments in pscs
Verdeplane (T): occur on stream terraces of mountain valleys; >60 inches to bedrock; no ash recognized; 18 to 34 percent clay in pscs
DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderate
USE AND VEGETATION:
Use: Timber production, watershed, wildlife, recreation, livestock grazing
Native vegetation: grand fir, Douglas fir, ponderosa pine, western larch, big huckleberry, grouse huckleberry, birchleaf spirea, common snowberry, western serviceberry, darkwoods violet, small cleavers, showy aster, trail plant, heartleaf arnica, bigleaf sandwort, mountain sweet-cicely, pinegrass, elk sedge, blue wildrye and western fescue.
DISTRIBUTION AND EXTENT:
MLRA--E43c, Blue Mountains
Distribution: Central Blue Mountains of northeastern Oregon.
Extent: small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Grant County, Oregon; 2004. Name is from a stream.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon: 1 to 6 inches; A horizon
cambic horizon: 6 to 45 inches; Bw, BC horizons
ash layerandic soil properties: 1 to 61 inches; A, Bw, BC, C horizons
particle-size control section: 1 to 41 inches; A, Bw, BC horizons
amorphic part: 1 to 25 inches; A, Bw horizons
glassy part: 25 to 41 inches; BC horizon
USFS Ecological site: ABGR/SPBE; may include: ABGR/VASC, ABGR/VAME, PSME/SYAL