LOCATION TWOCOLOR OR
Tentative Series
IRD. JLW/RJO/DAL/RWL
04/2013
TWOCOLOR SERIES
The Twocolor series consists of very deep, well drained soils on lateral moraines of glaciated mountain slopes. Twocolor soils formed in volcanic ash over till dominated by granitic rocks. Slopes are 0 to 60 percent. The mean annual precipitation is about 40 inches and the mean annual temperature is about 38 degrees F.
TAXONOMIC CLASS: Ashy over loamy-skeletal, glassy over isotic, frigid Typic Vitrixerands
TYPICAL PEDON: Twocolor stony ashy silt loam, woodland, on a 35 percent southeast-facing slope at an elevation of 5,830 feet. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 1 inches; needles, twigs, and leaves.
A--1 to 5 inches; dark brown (7.5YR 3/3) stony ashy silt loam, brown (7.5YR 4/4) dry; weak very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine and few medium and coarse roots; many very fine and common fine irregular pores; 5 percent gravel, 10 percent cobbles, and 10 percent stones; slightly acid (pH 6.5); clear wavy boundary. (3 to 8 inches thick)
Bw--5 to 19 inches; dark brown (7.5YR 3/4) stony ashy silt loam, strong brown (7.5YR 5/6) dry; weak fine and very fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and common fine, medium, and coarse roots; few fine and very fine irregular pores; 5 percent gravel, 10 percent cobbles, and 15 percent stones; slightly acid (pH 6.5); clear wavy boundary. (7 to 14 inches thick)
2EBb--19 to 33 inches; strong brown (7.5YR 4/6) extremely stony silt loam, brown (7.5YR 5/4) dry; weak very fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common fine, medium, and coarse roots; common very fine irregular pores; 20 percent gravel, 20 percent cobbles, and 25 percent stones; slightly acid (pH 6.5); gradual smooth boundary. (8 to 14 inches thick)
2Bwb--33 to 49 inches; dark brown (7.5YR 3/4) extremely stony loam, brown (7.5YR 5/4) dry; weak fine and very fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common fine and few medium and coarse roots; few fine irregular and few fine tubular pores; 20 percent gravel, 20 percent cobbles, and 25 percent stones; moderately acid (pH 6.0); gradual smooth boundary. (12 to 19 inches thick)
2C--49 to 61 inches; dark yellowish brown (10YR 3/4) extremely stony loamy sand, brown (10YR 5/3) dry; single grain; loose, very friable, nonsticky and nonplastic; few fine, medium, and coarse roots; 20 percent gravel, 20 percent cobbles, and 25 percent stones; moderately acid (pH 6.0). (6 to 19 inches thick)
TYPE LOCATION: Baker County, Oregon
Section 8 (NW , NE , NE ), T. 6 S., R. 43 E.
45 degrees, 3 minutes, 53 seconds Latitude
117 degrees, 27 minutes, 55 seconds Longitude
UTM Coordinates: Zone 11; Northing: 4,990,245.5; Easting: 463,370.3
USGS Quadrangle: Bennet Peak
RANGE IN CHARACTERISTICS:
Soil Temperature: frigid regime
Mean Annual Soil Temperature: 39 to 42 degrees F
Mean Summer Soil Temperature: 46 to 50 degrees F
Mean Winter Soil Temperature: 32 to 36 degrees F
Soil Moisture: xeric regime, dry 45 to 60 days in summer
Particle-size Control Section: mineral surface to 40 inches below the mineral surface
Upper part (ashy): 15 to 19 inches thick
Clay content (wt. avg.): 4 to 9 percent
Rock fragment content (wt. avg.): 15 to 25 percent
Lower part (loamy-skeletal): 21 to 25 inches thick
Clay content (wt. avg.): 8 to 20 percent
Rock fragment content (wt. avg.): 50 to 70 percent
Rock fragment shape: rounded
Diagnostic Horizons and Features:
andic soil properties: upper boundary at the mineral surface; 15 to 19 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 0.02-2.0mm 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
ochric epipedon: 3 to 8 inches thick
cambic horizon:
upper: 7 to 14 inches thick
lower: 20 to 33 inches thick
Major Horizons:
A horizon:
color, moist: 7.5YR 3/2, 3/3; 10YR 2/2
color, dry: 7.5YR 4/4, 5/4; 10YR 4/3, 4/4, 5/3
texture: ST-ASHY-SIL, ASHY-SIL, CB-ASHY-SIL
clay content: 4 to 10 percent
rock fragments: 5 to 25 percent
gravel: 5 to 10 percent
cobbles: 0 to 10 percent
stones: 0 to 10 percent
reaction: slightly acid or neutral; pH: 6.1 to 7.3
Bw horizon:
color, moist: 7.5YR 3/4, 4/4, 5/6; 10YR 3/6, 4/3
color, dry: 7.5YR 5/6, 6/4; 10YR 5/4, 5/6
texture: ST-ASHY-SIL, CB-ASHY-SIL, GR-ASHY-SIL, CB-ASHY-VFSL
clay content: 5 to 8 percent
rock fragments: 15 to 30 percent
gravel: 5 to 10 percent
cobbles: 5 to 15 percent
stones: 0 to 15 percent
reaction: slightly acid or neutral; pH: 6.1 to 7.3
2BEb horizon (2Eb, 2ABb in some pedons):
color, moist: 7.5YR 3/4, 4/6, 5/4; 10YR 4/4, 5/3
color, dry: 7.5YR 4/4, 5/4, 6/4; 10YR 5/3, 7/3
texture: STX-L, STX-SIL, STV-SL, CBV-L
clay content: 5 to 18 percent
rock fragments: 40 to 70 percent
gravel: 15 to 25 percent
cobbles: 15 to 25 percent
stones: 5 to 25 percent
reaction: moderately acid to slightly acid; pH: 5.6 to 6.5
2Bwb horizon:
color, moist: 7.5YR 3/4, 5/4; 10YR 4/6, 5/3
color, dry: 7.5YR 4/4, 5/4, 5/6; 10YR 5/4, 6/4
texture: STX-L, STV-SCL, CBV-L
clay content: 12 to 22 percent
rock fragments: 55 to 70 percent
gravel: 20 to 30 percent
cobbles: 15 to 25 percent
stones: 10 to 25 percent
reaction: moderately acid or slightly acid; pH: 5.6 to 6.5
2C horizon; (2BCb in some pedons):
color, moist: 2.5YR 4/6, 5/4; 10YR 3/4, 5/4
color, dry: 5YR 5/8; 10YR 5/3, 6/4
texture: STX-LS, GRV-CL, STV-SCL, CBV-L
clay content: 5 to 30 percent
rock fragments: 35 to 80 percent
gravel: 20 to 35 percent
cobbles: 10 to 25 percent
stones: 5 to 25 percent
reaction: slightly acid; pH: 6.1 to 6.5
COMPETING SERIES:
These are the
Endcreek (T),
Kingbolt (T),
Larrupin,
Poguepoint (T),
Raggedrock (T), and
Tertoo (T) series. Soils with a similar classification include the
Brannan,
Capoose,
Crackler,
Elbowlake,
Faraway (T),
Kellerbutte,
Kootenai,
Natapoc,
Nevine,
Olot,
Rouen,
Saska, and
Vingulch (T) series.
Endcreek soils - moderately deep (20 to 40 inches) to a lithic contact (granite)
Kingbolt soils - moderately deep (20 to 40 inches) to lithic contact (argillite); loamy-skeletal part of the pscs has 35 to 75 percent angular and subangular rock fragments of metavolcanic, metasedimentary rock or rhyolite origin of which less than 15 percent are cobbles and stones
Larrupin soils - ashy part of pscs has 30 to 60 percent volcanic glass and have a texture of ashy loamy sand or ashy sandy loam; loamy-skeletal part of pscs has 35 to 60 percent rounded or subrounded gravel and cobbles of mixed origin from mudflow material
Poguepoint soils - deep (40 to 60 inches) to a lithic contact (andesitic basalt); loamy-skeletal part of the pscs has 40 to 70 percent subangular gravel, cobbles and stones of andesitic basalt origin
Raggedrock soils - deep (40 to 60 inches) to a paralithic contact (granite); loamy-skeletal part of the pscs has 40 to 75 percent subrounded rock fragments of granite origin
Tertoo soils - MAST is 43 to 46 degrees F.; the 2Bwb horizon has 4 to 12 percent clay
Brannan soils - deep (40 to 60 inches) to a lithic contact (schist); ashy part of pscs has 15 to 35 percent channers and flags and glassy mineralogy; loamy-skeletal part of the pscs has 15 to 30 percent clay and 35 to 60 percent channers and flags
Capoose soils - moderately deep (20 to 40 inches) to a lithic contact (granite); ashy part of pscs has 30 to 60 percent volcanic glass and glassy mineralogy; loamy-skeletal part of pscs has 40 to 70 percent angular rock fragments of granitic origin; dry 60 to 75 consecutive days following the summer solstice
Crackler soils - deep (40 to 60 inches) to a lithic contact (argillite); ashy part of pscs has 15 to 30 pecent gravel and cobbles and glassy mineralogy; loamy-skeletal part of the pscs has 18 to 35 percent clay and 40 to 75 percent subangular gravel and cobbles
Elbowlake soils - moderately deep (20 to 40 inches) to a densic contact; ashy part of pscs has 30 to 60 percent volcanic glass and glassy mineralogy; loamy-skeletal part of the pscs has 12 to 18 percent clay
Farway soils - ashy part of pscs has 30 to 60 percent volcanic glass, texture of ashy sandy loam, and glassy mineralogy; dry 60 to 75 days consecutive days following the summer solstice
Kellerbutte soils - ashy part of pscs has 30 to 60 percent volcanic glass, 5 to 25 percent angular rock fragments and glassy mineralogy; rock fragments in loamy-skeletal part of pscs are angular
Kootenai soils - ashy part of pscs has 30 to 60 percent volcanic glass, 0.4 to 1.0 percent Al + 1/2Fe(aox), and glassy mineralogy; loamy-skeletal part of pscs has coarse sand or loamy coarse sand textures
Natapoc soils - very deep (>60 inches) to a densic contact; ashy part of pscs 30 to 60 percent volcanic glass, ashy sandy loam texture, and glassy mineralogy; dry 60 to 75 consecutive days following the summer solstice
Nevine soils - deep (40 to 60 inches) to a densic contact; ashy part of pscs has 30 to 60 percent volcanic glass and glassy mineralogy; dry 60 to 75 consecutive days following the summer solstice
Olot soils - moderately deep (20 to 40 inches) to a lithic contact (basalt); ashy part of pscs has glassy mineralogy; loamy-skeletal part of the pscs has 25 to 35 percent clay and 35 to 75 percent angular and subangular rock fragments
Rouen soils - moderately deep (20 to 40 inches) to a lithic contact (argillite); ashy part of pscs has glassy mineralogy; loamy-skeletal part of the pscs has 25 to 35 percent clay and 35 to 70 percent angular and subangular gravel and cobbles
Saska soils - ashy part of pscs has 30 to 60 percent volcanic glass and glassy mineralogy with a texture of ashy loamy sand or ashy sandy loam mixed with pumice; Bs horizons 14 to 24 inches thick
Vingulch soils - moderately deep (20 to 40 inches) to a lithic contact (gneiss); ashy part of pscs has 30 to 60 percent volcanic glass, glassy mineralogy, and texture of ashy loamy very fine sand and ashy coarse sandy loam with 10 to 25 percent pumice; dry 60 to 75 consecutivd days following the summer solstice
GEOGRAPHIC SETTING:
Landform: lateral moraines on glaciated mountain slopes
Slope gradient: 15 to 60 percent
Parent material: volcaniclastic volcanic ash overlying colluvium
Lithology: granitic till over granite
Elevation: 5,000 to 6,000 feet
Climate: cold, wet winters and warm, dry summers
Mean annual precipitation: 35 to 45 inches
Mean annual air temperature: 37 to 40 degrees F
Frost-free period: 30 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Bigelk (T) soils - occur on shoulder slopes; ; volcanic ash mantle is <14 inches thick; mollic epipedon
Inkler soils - occur on steeper, drier slopes; volcanic ash mantle is <14 inches thick; 60 to 75 dry days in summer
DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderately slow
USE AND VEGETATION:
Use: watershed, wildlife habitat, timber production, livestock grazing and recreation.
Native vegetation: grand fir, western larch, Douglas fir, ponderosa pine, big huckleberry, birchleaf spirea, sitka alder, prince's pine, big leaf sandwort, whiteflowered hawkweed, heartleaf arnica, bracken fern, violet, pinegrass and northwestern sedge.
DISTRIBUTION AND EXTENT:
MLRA--E43c, Blue Mountains
Distribution: Blue Mountains of northeastern Oregon
Extent: small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Baker County, Oregon 2004. The name is from a guard station along Eagle Creek.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon: 1 to 5 inches; A horizon
cambic horizon:
upper: 5 to 19 inches; Bw horizon
lower: 19 to 49 inches; 2EBb, 2Bwb horizons
andic soil properties: 1 to 19 inches; A, Bw horizons
particle-size control section:
ashy part: 1 to 19 inches; A, Bw horizons
loamy-skeletal part: 19 to 41 inches; 2EBb, 2Bwb horizons
USFS Ecological site: ABGR/CARU; others may include: ABGR/SPBE and ABGR/VAME.
National Cooperative Soil Survey
U.S.A.