LOCATION MCWILLIS OR
Tentative Series
IRD. AEK/RJO/DAL/KMS
02/2019
MCWILLIS SERIES
Landscape--mountains, plateaus
Landform--mountain slopes, plateaus
Slope--0 to 60 percent
Parent material--thick mantle of volcanic ash over colluvium and residuum derived from andesite or basalt
Mean annual precipitation--about 730 mm
Mean annual air temperature--about 4 degrees C
Depth class--very deep
Drainage class--well drained
Soil moisture regime--xeric
Soil temperature regime--frigid
Soil moisture subclass--typic
TAXONOMIC CLASS: Ashy over loamy-skeletal, glassy over isotic, frigid Alfic Vitrixerands
TYPICAL PEDON: McWillis stony ashy silt loam under a conifer forest, on a 45-percent, northeast-facing slope at an elevation of 1597 m
Oi--0 to 8 cm; slightly decomposed needles and twigs
A--8 to 10 cm; stony ashy silt loam, light yellowish brown (10YR 6/4) dry, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and very fine roots; many fine and few medium irregular pores; 10 percent gravel and 5 percent stones; moderately acid (pH 6.0); clear smooth boundary
Bw--10 to 48 cm; gravelly ashy silt loam, light yellowish brown (10YR 6/4) dry, dark yellowish brown (10YR 3/4) moist; weak medium subangular blocky structure parting to weak fine subangular blocky; soft, very friable, nonsticky and nonplastic; few very fine and coarse and common fine and medium roots; few fine tubular pores; 15 percent gravel and 5 percent stones; moderately acid (pH 6.0); abrupt smooth boundary
2Eb--48 to 64 cm; very stony loam, brown (10YR 5/3) dry, brown (10YR 4/3) moist; moderate fine and very fine subangular blocky structure; soft, friable, slightly sticky and nonplastic; common fine, medium, and coarse roots; few fine tubular pores; 20 percent gravel, 10 percent cobbles, and 10 percent stones; moderately acid (pH 6.0); clear smooth boundary
2Btb1--64 to 94 cm; very cobbly loam, brown (10YR 5/3) dry, brown (10YR 4/3) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; slightly hard, firm, moderately sticky and slightly plastic; many faint clay films on ped faces; few fine, medium, and coarse roots; few fine tubular pores; 25 percent gravel, 15 percent cobbles, and 5 percent stones; moderately acid (pH 6.0); gradual smooth boundary
2Btb2--94 to 122 cm; very cobbly loam, brown (10YR 5/3) dry, brown (10YR 4/3) moist; weak fine and medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; many faint clay films on ped faces and colloid stains on mineral grains; few fine, medium, and coarse roots; few fine tubular pores; 30 percent gravel, 20 percent cobbles, and 5 percent stones; moderately acid (pH 6.0); gradual smooth boundary
2BCtb--122 to 155 cm; extremely cobbly loam, yellowish brown (10YR 5/4) dry, brown (10YR 4/3) moist; weak fine and medium angular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; few faint clay films on ped faces; few fine and medium roots; 30 percent gravel, 25 percent cobbles, and 5 percent stones; moderately acid (pH 6.0)
TYPE LOCATION: Baker County, Oregon, about 330 m west and 418 m south of the northeast corner of section 20, T. 13 S., R. 36 E.; latitude 44.4267000, longitude -118.3165470, datum WGS 84 (coordinates and PLSS details estimated from point on hard copy map)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--about 3 to 7 degrees C
Mean summer soil temperature--about 7 to 12 degrees C
Mean winter soil temperature--about 0 to 3 degrees C
Soil moisture--dry 45 to 60 consecutive days in summer
Thickness of ash-influenced layers--35 to 60 cm
Estimated properties of layers influenced by volcanic ash
*Ammonium oxalate extractable Al + 1/2 Fe--1 to 2 percent
*0.02- to 2.0-mm fraction--40 to 70 percent
*Glass content in 0.02- to 2.0-mm fraction--60 to 90 percent
*1/3-bar bulk density--0.70 to 1.00 g/cm3
*Phosphate retention--40 to 70 percent
*15-bar water retention--5 to 12 percent (dried samples)
*8 x Si plus 2 x Fe--5 to 8 percent; 8 Si more than twice 2 Fe (amorphic)
Particle-size control section
*Clay content--4 to 8 percent in upper part, 12 to 18 percent in lower part
*Total rock fragment content--10 to 30 percent in upper part, 35 to 85 percent in lower part
A horizon
Moist color--7.5YR 4/2, 10YR 3/2, 10YR 3/3, 10YR 3/4
Dry color--7.5YR 6/2, 10YR 4/3, 10YR 5/3, 10YR 5/4, 10YR 6/4
Fine-earth texture--ashy silt loam
Clay content--4 to 8 percent
Sand content--35 to 45 percent
Organic matter content--2 to 6 percent
Total rock fragment content--5 to 25 percent
Gravel content--5 to 15 percent
Cobble content--0 to 5 percent
Stone content--0 to 10 percent
Reaction--5.6 to 6.5
Thickness--2 to 20 cm
Bw horizon
Moist color--7.5YR 5/4, 10YR 3/4, 10YR 4/3, 10YR 5/4, 10YR 5/6
Dry color--7.5YR 6/4, 10YR 5/4, 10YR 6/3, 10YR 6/4, 10YR 7/4
Fine-earth texture--ashy silt loam
Clay content--4 to 8 percent
Sand content--35 to 45 percent
Organic matter content--1 to 3 percent
Total rock fragment content--5 to 30 percent
Gravel content--5 to 20 percent
Cobble content--0 to 5 percent
Stone content--0 to 10 percent
Reaction--5.6 to 7.3
Thickness--25 to 45 cm
2Eb horizon, and 2EBb, 2AEb, 2Bwb, or 2Ab horizon (where present)
Moist color--5YR 4/3, 5YR 4/4, 10YR 4/3, 10YR 5/3
Dry color--5YR 5/3, 10YR 5/3, 10YR 5/4, 10YR 6/3
Fine-earth texture--loam
Clay content--10 to 18 percent
Sand content--45 to 52 percent
Organic matter content--1.5 to 3.5 percent
Total rock fragment content--35 to 60 percent
Gravel content--15 to 40 percent
Cobble content--0 to 25 percent
Stone content--0 to 30 percent
Reaction--5.6 to 7.3
Thickness--15 to 55 cm
2Btb horizon
Moist color--5YR 4/4, 7.5YR 4/3, 10YR 4/2, 10YR 4/3, 10YR 5/4
Dry color--5YR 5/4, 7.5YR 6/3, 10YR 5/3, 10YR 5/4, 10YR 7/4
Fine-earth texture--loam
Clay content--15 to 27 percent
Sand content--40 to 50 percent
Organic matter content--0.5 to 2.0 percent
Total rock fragment content--40 to 85 percent
Gravel content--20 to 50 percent
Cobble content--5 to 25 percent
Stone content--0 to 30 percent
Reaction--5.6 to 7.3
Combined thickness--20 to 130 cm
2BCtb horizon
Moist color--5YR 3/4, 10YR 4/2, 10YR 4/3
Dry color--5YR 4/4, 10YR 5/4, 10YR 6/2
Fine-earth texture--loam, sandy loam
Clay content--12 to 18 percent
Sand content--40 to 70 percent
Organic matter content--0.3 to 1.5 percent
Total rock fragment content--60 to 70 percent
Gravel content--30 to 35 percent
Cobble content--20 to 25 percent
Stone content--5 to 15 percent
Reaction--5.6 to 7.3
COMPETING SERIES:
Crosswhite--50 to 100 cm (moderately deep) to lithic contact (andesite)
Maset--50 to 100 cm (moderately deep) to paralithic contact (sandstone)
Shaser--less than 60 percent glass in upper part
Windego--more than 50 percent sand in ash-influenced layers
GEOGRAPHIC SETTING:
Elevation--1050 to 2080 m
Climate--cold, wet winters; warm, dry summers
Mean annual precipitation--470 to 940 mm
Mean annual air temperature--2 to 7 degrees C
Frost-free period--25 to 80 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Cherrycreek--on north-facing mid slopes of plateaus and canyons; 100 to 150 cm (deep) to lithic contact (basalt); mixed ash and loess mantle over colluvium; thick mollic epipedon; under Idaho fescue, bluebunch wheatgrass, and snowberry
Fivebit--on plateaus and backslopes; 25 to 50 cm (shallow) to lithic contact (andesite); minor influence of volcanic ash in loamy-skeletal colluvium; under scattered ponderosa pine,
Douglas-fir, or western juniper and an understory of big sagebrush and Idaho fescue
Olot--on plateaus and side slopes of mountains; 50 to 100 cm (moderately deep) to lithic contact (basalt); thick volcanic ash mantle over loamy-skeletal material; under
Douglas-fir forest
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Saturation during normal years--none
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--moderately high
USE AND VEGETATION:
Use--watershed, wildlife habitat, timber production, livestock grazing, recreation
Potential native vegetation-- Douglas-fir, grand fir, ponderosa pine, Engelmann spruce, western larch, subalpine fir, lodgepole pine, pinegrass, elk sedge, grouse huckleberry, heartleaf arnica, northwestern sedge, pinemat manzanita, northern twinflower, prince's pine, white hawkweed, tailcup lupine, big huckleberry, common snowberry, white spirea, Virginia strawberry, pyrola, baldhip rose, woodland strawberry
DISTRIBUTION AND EXTENT: Northeastern Oregon; MLRAs 9 and 10; small extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wallowa-Whitman National Forest, Oregon; 2018
REMARKS:
Diagnostic horizons and other features recognized in this pedon
*Ochric epipedon
*Cambic horizon--zone from 10 to 48 cm
*Argillic horizon--zone from 64 to 122 cm
*Volcanic glass--zone from 8 to 48 cm
*Andic soil properties--zone from 8 to 48 cm
*Particle-size control section--ashy part includes zone from 8 to 48 cm; loamy-skeletal part includes zone from 48 to 109 cm
Amorphic mineralogy class for the ash mantle is based on laboratory data for soils that have an undisturbed ashy silt loam mantle, xeric moisture regime, and 45 to 60 consecutive dry days in summer in 8 out of the 13 pedons sampled.
National Cooperative Soil Survey
U.S.A.