LOCATION MCWILLAR                OR

Established Series
IRD. JLW/RJO/DAL/KMS
02/2019

MCWILLAR SERIES

Landscape--mountains
Landform--mountain slopes
Slope--0 to 90 percent
Parent material--thick mantle of volcanic ash over colluvium derived from metasedimentary rock and sandstone
Mean annual precipitation--about 700 mm
Mean annual air temperature--about 4 degrees C
Depth class--deep to lithic contact
Drainage class--well drained
Soil moisture regime--xeric
Soil temperature regime--frigid
Soil moisture subclass--typic
e
TAXONOMIC CLASS: Ashy over loamy-skeletal, amorphic over isotic, frigid Alfic Vitrixerands

TYPICAL PEDON: McWillar gravelly ashy silt loam under a conifer forest, on a 25-percent, north-facing slope at an elevation of 1852 m

Oi--0 to 3 cm; slightly decomposed needles and twigs

A--3 to 8 cm; gravelly ashy silt loam, pale brown (10YR 6/3) dry, brown (10YR 4/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and very fine roots; common fine irregular pores; 25 percent gravel; neutral (pH 7.0); gradual smooth boundary

Bw--8 to 41 cm; gravelly ashy silt loam, pale brown (10YR 6/3) dry, dark yellowish brown (10YR 4/4) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine and very fine and common medium and coarse roots; few fine irregular pores; 30 percent gravel; slightly acid (pH 6.5); clear smooth boundary

2Eb--41 to 51 cm; very gravelly sandy loam, light brown (7.5YR 6/4) dry, brown (7.5YR 5/4) moist; weak very fine subangular blocky structure; soft, friable, nonsticky and nonplastic; common fine and medium and few coarse roots; common fine irregular pores; 55 percent gravel; slightly acid (pH 6.5); clear smooth boundary

2EBb--51 to 76 cm; very gravelly sandy loam, light yellowish brown (10YR 6/4) dry, yellowish brown (10YR 5/4) moist; weak very fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common fine and few medium and coarse roots; few fine irregular and tubular pores; 60 percent gravel; slightly acid (pH 6.5); clear smooth boundary

2Btb1--76 to 99 cm; extremely gravelly sandy loam, very pale brown (10YR 7/4) dry, yellowish brown (10YR 5/4) moist; moderate fine and very fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common faint clay films on ped faces; common fine and few medium roots; few fine tubular pores; 65 percent gravel; slightly acid (pH 6.5); gradual smooth boundary

2Btb2--99 to 117 cm; extremely gravelly sandy clay loam, brownish yellow (10YR 6/6) dry, yellowish brown (10YR 5/6) moist; moderate fine and very fine angular blocky structure; very hard, very firm, moderately sticky and moderately plastic; many distinct clay films on ped faces and rock fragments; few fine roots; 65 percent gravel; slightly acid (pH 6.5); gradual smooth boundary

2BCtb--117 to 135 cm; extremely gravelly sandy loam, very pale brown (10YR 7/3) dry, light yellowish brown (10YR 6/4) moist; weak very fine subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; few faint clay films on rock fragments; few fine irregular pores; 85 percent gravel; slightly acid (pH 6.5); clear smooth boundary

2R--135 cm; fractured argillite

TYPE LOCATION: Baker County, Oregon, about 490 m west and 240 m north of the southeast corner of section 6, T. 15 S., R. 37 E.; latitude 44.2871820, longitude -118.2193880, 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
Depth to lithic contact (below mineral soil surface)--100 to 150 cm
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--50 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
*Ashy upper part--35 to 60 cm thick; average of 4 to 8 percent clay and 5 to 30 percent rock fragments
*Loamy-skeletal lower part--40 to 65 cm thick; average of 12 to 18 percent clay and 35 to 65 percent rock fragments

A horizon
Moist color--7.5YR 3/2, 10YR 3/1, 10YR 3/3, 10YR 3/4, 10YR 4/3
Dry color--7.5YR 5/2, 10YR 4/1, 10YR 5/4, 10YR 6/3, 10YR 6/4
Fine-earth texture--ashy silt loam
Clay content--4 to 8 percent
Sand content--40 to 45 percent
Organic matter content--2 to 6 percent
Total rock fragment content--5 to 25 percent
Gravel content--5 to 25 percent
Reaction--5.6 to 7.3
Thickness--5 to 15 cm

Bw horizon, and AE or AB horizon (where present)
Moist color--7.5YR 5/2, 10YR 3/6, 10YR 4/3, 10YR 4/4, 10YR 5/4
Dry color--7.5YR 6/2, 10YR 5/3, 10YR 6/3, 10YR 6/4, 10YR 7/4, 10YR 7/6
Fine-earth texture--ashy silt loam
Clay content--4 to 8 percent
Sand content--40 to 45 percent
Organic matter content--1 to 3 percent
Total rock fragment content--10 to 30 percent
Gravel content--10 to 30 percent
Reaction--5.6 to 6.5
Thickness--25 to 45 cm

2Eb and 2EBb horizons, and 2Bwb horizon (where present)
Moist color--7.5YR 4/4, 7.5YR 5/4, 7.5YR 7/4, 10YR 4/4, 10YR 5/4, 10YR 6/4
Dry color--7.5YR 6/4, 7.5YR 8/4, 10YR 5/3, 10YR 5/4, 10YR 6/3, 10YR 6/4, 10YR 7/4
Fine-earth texture--loam, sandy loam
Clay content--3 to 16 percent
Sand content--50 to 70 percent
Organic matter content--1.0 to 3.5 percent
Total rock fragment content--35 to 70 percent
Gravel content--30 to 65 percent
Cobble content--0 to 10 percent
Stone content--0 to 5 percent
Reaction--5.6 to 6.5
Combined thickness of 2Eb and 2EBb horizons--25 to 50 cm

2Btb horizon
Moist color--7.5YR 5/6, 10YR 5/4, 10YR 5/6, 10YR 6/4, 10YR 7/4, 10YR 7/6, 2.5Y 6/6
Dry color--7.5YR 6/6, 10YR 6/4, 10YR 7/6, 2.5Y 6/6
Fine-earth texture--loam, sandy loam, sandy clay loam
Clay content--15 to 25 percent
Sand content--45 to 70 percent
Organic matter content--0.5 to 2.0 percent
Total rock fragment content--45 to 70 percent
Gravel content--45 to 70 percent
Cobble content--0 to 10 percent
Reaction--5.6 to 6.5
Combined thickness--25 to 50 cm

2BCtb horizon
Moist color--10YR 6/4, 10YR 6/6, 2.5Y 6/4
Dry color--10YR 7/3, 10YR 8/4, 2.5Y 6/4
Fine-earth texture--sandy clay loam, sandy loam
Clay content--15 to 25 percent
Sand content--65 to 85 percent
Organic matter content--0.5 to 1.5 percent
Total rock fragment content--70 to 90 percent
Gravel content--65 to 85 percent
Cobble content--0 to 10 percent
Reaction--5.6 to 6.5
Thickness--0 to 25 cm

COMPETING SERIES:
Slaughterhouse--deep (100 to 150 cm) to lithic contact (metavolcanic rock); average of 18 to 27 percent clay in lower part of particle-size control section

GEOGRAPHIC SETTING:
Elevation--1190 to 1870 m
Climate--cold, wet winters; warm, dry summers
Mean annual precipitation--570 to 860 mm
Mean annual air temperature--2 to 6 degrees C
Frost-free period--25 to 80 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Analulu--on convex backslopes and ridges; 50 to 100 cm (moderately deep) to lithic contact (metasedimentary or metavolcanic rock); minor influence of volcanic ash; under Douglas-fir, ponderosa pine, or grand fir forest
Kingbolt--on ridges, benches, and shoulder slopes; 50 to 100 cm (moderately deep) to lithic contact (metasedimentary rock, metavolcanic rock, sandstone, rhyolite); thick volcanic ash mantle; under grand fir and 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--grand fir, western larch, Douglas-fir, ponderosa pine, birchleaf spirea, common snowberry, heartleaf arnica, white-flowered hawkweed, common yarrow, mountain sweet-cicely, woods strawberry, pussytoes, pinegrass

DISTRIBUTION AND EXTENT: Blue Mountains of northeastern Oregon; MLRA 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 8 to 41 cm
*Argillic horizon--zone from 76 to 117 cm
*Volcanic glass--zone from 3 to 41 cm
*Andic soil properties--zone from 3 to 41 cm
*Particle-size control section--ashy part includes zone from 3 to 41 cm; loamy-skeletal part includes zone from 41 to 104 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.