LOCATION BIGCOW ORTentative Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Andic Haploxerepts
TYPICAL PEDON: Bigcow gravelly ashy silt loam - forested, on a 30 percent planar, northeast - facing slope at an elevation of 5,750 feet. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 2 inches; slightly decomposed needles and twigs.
A--2 to 4 inches; brown (10YR 4/3) gravelly ashy silt loam, brown (10YR 5/3) dry; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, and common medium roots; common fine irregular pores; 15 percent gravel; neutral (pH 7.0); clear smooth boundary. (1 to 4 inches thick)
Bw1--4 to 7 inches; yellowish brown (10YR 5/4) gravelly ashy silt loam, very pale brown (10YR 7/4) dry; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, and few medium and coarse roots; common fine tubular pores; 15 percent gravel; neutral (pH 7.0); clear smooth boundary.
Bw2--7 to 13 inches; light yellowish brown (10YR 6/4) gravelly ashy silt loam, very pale brown (10YR 8/4) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many fine, medium and coarse roots; common fine tubular pores; 15 percent gravel; neutral (pH 7.0); abrupt wavy boundary. (combined thickness of Bw horizons is 8 to 11 inches)
2Eb--13 to 20 inches; brown (10YR 5/3) very gravelly loam, very pale brown (10YR 7/3) dry; weak very fine and fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many fine, common medium and coarse roots; few fine irregular pores; 40 percent gravel and 5 percent cobbles; slightly acid (pH 6.5); clear smooth boundary. (6 to 15 inches thick)
2Bwb--20 to 35 inches; light yellowish brown (10YR 6/4) very gravelly loam, very pale brown (10YR 7/3) dry; weak very fine and fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many fine, common medium and coarse roots; common fine irregular pores; 45 percent gravel and 10 percent cobbles; slightly acid (pH 6.5); gradual smooth boundary. (12 to 18 inches thick)
2BCb--35 to 63 inches; light yellowish brown (10YR 6/4) extremely gravelly loamy sand, pale brown (10YR 6/3) dry; single grain; loose, nonsticky and nonplastic; common fine and few medium roots; many fine, common medium and few coarse irregular pores; 60 percent gravel, 15 percent cobbles and 10 percent stones; neutral (pH 7.0).
TYPE LOCATION: Baker County, Oregon,
Section 13 (SE1/4, SE1/4, NE1/4) T. 13 S., R. 35 1/2 E.
Latitude: 44 degrees, 26 minutes, 22 seconds N
Longitude: 118 degrees, 21 minutes, 12 seconds W
UTM Coordinates: Zone 11; Northing: 4,921,357; Easting: 392,298 NAD 27
RANGE IN CHARACTERISTICS:
Soil temperature regime: frigid
Mean Annual Soil Temperature: 40 to 44 degrees F
Mean Summer Soil Temperature: 47 to 51 degrees F
Mean Winter Soil Temperature: 32 to 36 degrees F
Soil Moisture Regime: xeric, dry 45 to 60 consecutive days in summer
Particlesize Control Section: from 10 to 40 inches below the mineral soil surface
Clay content, average: 9 to 16 percent
Rock fragment content, average: 45 to 65 percent
Diagnostic Horizons and Features:
andic subgroup properties: 9 to 13 inches thick
Al+1/2Fe (ammonium oxalate): 1.0 to 2.8 percent
bulk density: 0.65 to 1.0 g/cc
P retention: 50 to 80 percent
0.022.0 mm fraction: 40 to 60 percent of fine earth
glass content in 0.022.0mm fraction: 50 to 85 percent
cambic horizon, upper: 8 to 11 inches thick
cambic horizon, buried: 12 to 18 inches thick
lithic contact, depth below mineral soil surface: 40 to 80 inches
A horizon
color, moist: 7.5YR 4/2; 10YR 3/2, 3/3, 4/2, 4/3
color, dry: 7.5YR 5/2; 10YR 5/3, 6/3, 6/4
texture GR-ASHY-SIL
clay content: 4 to 7 percent
rock fragments: 15 to 25 percent
gravel 15 to 25 percent
cobbles 0 to 5 percent
reaction: slightly acid or neutral; pH: 6.1 to 7.0
Bw horizon
color, moist: 7.5YR 5/4; 10YR 4/3, 4/4, 5/3, 5/4, 6/4
color, dry: 7.5YR 6/4; 10YR 5/4, 6/4, 7/4, 8/4
texture: GR-ASHY-SIL
clay content: 4 to 7 percent
rock fragments: 15 to 30 percent total
gravel: 15 to 30 percent
cobbles: 0 to 5 percent
stones: 0 to 5 percent
reaction: slightly acid or neutral; pH: 6.1 to 7.0
2Eb horizon
color, moist: 7.5YR 4/3; 10YR 4/2, 4/4, 5/3, 5/4
color, dry: 7.5YR 6/2; 10YR 6/3, 6/4, 7/3
texture: GRV-L
clay content: 9 to 16 percent
rock fragments: 35 to 50 percent total
gravel: 30 to 40 percent
cobbles: 5 to 10 percent
stones: 0 to 5 percent
reaction: slightly acid or neutral; pH: 6.1 to 7.0
2Bwb horizon
color, moist: 7.5YR 4/2, 4/4; 10YR 4/4, 6/4
color, dry: 7.5YR 5/4, 6/4; 10YR 5/4, 6/3, 7/3
texture: GRV-L, STV-L
clay content: 10 to 17 percent
rock fragments: 40 to 60 percent total
gravel: 25 to 50 percent
cobbles: 5 to 15 percent
stones: 0 to 15 percent
reaction: slightly acid or neutral; pH: 6.1 to 7.0
2BCb horizon
color, moist: 7.5YR 4/4, 5/4; 10YR 4/4, 6/4
color, dry: 7.5YR 5/3, 6/4;10YR 5/3, 5/4, 6/3
texture: GRV-SL, GRX-L, STX-L, GRX-LS
clay content: 5 to 20 percent
rock fragments: 55 to 90 percent total
gravel: 35 to 60 percent
cobbles: 5 to 20 percent
stones: 0 to 15 percent
reaction: slightly acid or neutral; pH: 6.1 to 7.0
COMPETING SERIES:
Avonville; formed in glacial outwash; umbric epipedon
Hondu; formed in argillite colluvium ; clay content in particle-size control section averages 3 to 9 percent
Inkler; deep and very deep (40 to greater than 60 inches) to a lithic contact (metamorphic or volcanic); formed in glacial till, or colluvium, and residuum from volcanic and metamorphic rocks; dry for 60 to 75 consecutive days in summer
Juandefuca; very deep; formed in colluvium from marine basalt; ash mantle has greater than 12 percent (air dried) water content at 1500 kPa (i.e. medial) and volcanic glass content less than 30 percent
McCree; deep (40 to 60 inches) to a lithic contact (rhyolite); ash mantle has 5 to 20 percent volcanic glass content; dry 60 to 75 consecutive days in summer
Newhorn; moderately deep (20 to 40 inches) to a densic contact (till); dry 60 to 75 consecutive days in summer
Oxerine; moderately deep (20 to 40 inches) to a lithic contact (gneiss); dry 60 to 75 consecutive days in summer
Piutespring; moderately deep (20 to 40 inches) to a lithic contact (granitic rock); clay content in particle-size control section averages 2 to 9 percent
Redriver; moderately deep (20 to 40 inches) to a lithic contact (basalt); dry 75 to 90 consecutive days in summer
Tunnelcreek; moderately deep (20 to 40 inches) to a paralithic contact over metavolcanic bedrock; ash mantle has greater than 12 percent (air dried) water content at 1500 kPa (i.e. medial)
Veridge; moderately deep (20 to 40 inches) to a lithic contact (sandstone); thin volcanic ash mantle has 30 to 60 percent volcanic glass content; less than 10 percent clay in particle-size control section; dry 60 to 75 consecutive days in summer
Wilma soils; moderately deep (20 to 40 inches) to a lithic contact (granite); 2C or 2BC horizons with hue of 2.5Y; dry 60 to 75 consecutive days in summer
Wonder; moderately deep (20 to 40 inches) to a lithic contact (andesitic basalt)
GEOGRAPHIC SETTING:
Landform: backslopes of mountains
Elevation: 5,100 to 6,500 feet
Slope: 15 to 60 percent
Parent material: volcanic ash over colluvium from andesitic basalt
Bedrock: andesitic basalt, basalt
Climate: cool, wet winters and cool to warm, dry summers
Mean annual precipitation: 20 to 30 inches
Mean annual temperature: 36 to 40 degrees F
Frostfree period: 25 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Bennettcreek: on lower backslopes and footslopes, moderately deep to bedrock with a mixed mantle of ash and colluvium over loamy-skeletal argillic horizon; under grand fir, Douglas-fir, ponderosa pine, birchleaf spiraea, and pinegrass
Cherrycreek: on north-facing midslopes of plateaus and canyons, deep to bedrock with mixed ash and loess mantle over colluvium and thick mollic epipedon under Idaho fescue, bluebunch wheatgrass and snowberry
Larabee: on hill backslopes and shoulders, and canyons of dissected basalt plateaus; mollic epipedon and argillic horizon; under Douglas-fir, ponderosa pine, mallow ninebark, common snowberry and elk sedge
Linecreek: on hillslopes; very deep; volcanic ash mixed with basalt colluvium; mollic epipedon, cambic horizon, skeletal; under Douglas-fir, ponderosa pine, mallow ninebark, pinegrass and elk sedge
McWillis: on planar to concave, lower backslopes; deep to bedrock; thick volcanic ash mantle and argillic horizon; under grand fir or Douglas-fir and birchleaf spiraea
Olot: on plateaus and side slopes of mountains, moderately deep with a thick volcanic ash mantle over loamy-skeletal subsoil under Douglas-fir forest
Wonder: on ridges and shoulder slopes, moderately deep to bedrock with a thin volcanic ash mantle and loamy-skeletal particle size-control section under grand fir or Douglas-fir forest
DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderate to moderately rapid
USE AND VEGETATION:
Use: timber production, domestic grazing, watershed, wildlife and recreation.
Potential native vegetation: grand fir, lodgepole pine, Douglas-fir, ponderosa pine, grouse whortleberry, scoulers willow, Oregon boxwood, buffaloberry, bearberry, heartleaf arnica, yarrow, western hawkweed, fireweed, blueleaf strawberry, pinegrass, northwestern sedge and elk sedge.
Plant Associations: PICO (ABGR)/VASC (lodgepole pine (grand fir)/grouse whortleberry), ABGR/VASC (grand fir/grouse whortleberry) and PICO (ABGR)/CARU (lodgepole pine (grand fir/pinegrass)
DISTRIBUTION AND EXTENT:
Distribution: MLRA: 43c, Blue Mountains of northeastern Oregon
Extent: small
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Wallowa-Whitman National Forest, Oregon 2008. The source of the name is a forest fire in the area where the soil is mapped.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon: 2 to 4 inches; A
cambic horizon: 4 to 13 inches; Bw1, Bw2
cambic horizon, buried: 20 to 35 inches; 2Bwb
andic subgroup properties (ash mantle): 2 to 13 inches; A, Bw1, Bw2
particle-size control section: 12 to 42 inches; Bw2, 2Eb, 2Bwb, 2BCb