LOCATION BIGBOULDERCREEK OR
Established Series
Rev. JLW/RJO/DAL
11/2018
BIGBOULDERCREEK SERIES
Landscape--mountains
Landform--terraces on mountain valleys
Slope--0 to 15 percent
Parent material--thick mantle of volcanic ash over alluvium derived from mixed sources
Mean annual precipitation--about 680 mm
Mean annual air temperature--about 6 degrees C
Depth class--very deep
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--frigid
Soil moisture subclass--typic
TAXONOMIC CLASS: Ashy, amorphic, frigid Typic Udivitrands
TYPICAL PEDON: Bigbouldercreek ashy silt loam in an area of woodland, on a 15-percent, south-facing slope at an elevation of 1075 m (Soil textures are apparent field textures.)
Oi--0 to 5 cm; leaves, twigs, and needles
Oe--5 to 10 cm; moderately decomposed leaves, needles, and twigs
A--10 to 41 cm; ashy silt loam, pale brown (10YR 6/3) dry, dark brown (10YR 3/3) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic, weakly smeary; common very fine and fine, many medium, and common coarse roots; few very fine and fine tubular pores; strongly acid (pH 5.5); gradual smooth boundary
Bw--41 to 114 cm; ashy silt loam, very pale brown (10YR 7/3) dry, brown (10YR 4/3) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic, weakly smeary; common very fine, fine, and medium and few coarse roots; few very fine tubular pores; moderately acid (pH 6.0); clear irregular boundary
BC--114 to 137 cm; ashy silt loam, very pale brown (10YR 8/2) dry, brown (10YR 5/3) moist; weak very fine subangular blocky structure parting to massive; soft, very friable, nonsticky and nonplastic, weakly smeary; few very fine, fine, and medium roots; no pores recorded; slightly acid (pH 6.5); abrupt wavy boundary
2ABb--137 to 155 cm; loam, brown (7.5YR 5/3) dry, dark brown (7.5YR 3/3) moist; moderate coarse subangular blocky structure parting to common fine subangular blocky; slightly hard, friable, moderately sticky and moderately plastic; few very fine and fine roots; few very fine tubular pores; neutral (pH 7.2)
TYPE LOCATION: Grant County, Oregon; in the SE1/4SE1/4SE1/4 of section 20, T. 7 S., R. 31 E.; Meadow Brook Summit U.S. Geological Survey quadrangle; latitude 44.9408136, longitude -119.0026743 WGS 84 (Coordinates estimated from PLSS details)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--5 to 8 degrees C
Soil moisture--dry 25 to 45 days in summer
Thickness of cambic horizon--90 to 150 cm
Thickness of ash-influenced layers--100 to 180 cm
Estimated properties of layers influenced by volcanic ash
*Ammonium oxalate extractable Al + 1/2 Fe--1 to 3 percent
*0.02- to 2.0-mm fraction--40 to 60 percent
*Volcanic ash content in 0.02- to 2.0-mm fraction--60 to 90 percent
*1/3-bar bulk density--0.65 to 1.0 g/cm3
*Phosphate retention--40 to 90 percent
*15-bar water retention--5 to 12 percent (dried samples)
*8 x Si plus 2 x Fe--5 to 12 percent
*8 x Si minus 2 x Fe--4 to 8 percent
Particle-size control section
*Clay content--2 to 12 percent
A horizon
Moist color--7.5YR 3/2, 7.5YR 4/3, 7.5YR 4/4, 10YR 2/2, 10YR 3/3
Dry color--7.5YR 5/4, 7.5YR 6/2, 7.5YR 6/3, 10YR 4/3, 10YR 5/3, 10YR 6/3
Fine-earth texture--ashy silt loam
Clay content--5 to 10 percent
Reaction--5.1 to 7.3
Organic matter content--2 to 6 percent
Thickness--8 to 30 cm
Bw horizon
Moist color--7.5YR 3/4, 7.5YR 4/4, 10YR 4/3, 10YR 6/4
Dry color--7.5YR 5/4, 10YR 6/6, 10YR 7/2, 10YR 7/3
Fine-earth texture--ashy silt loam
Clay content --2 to 8 percent
Reaction--5.1 to 7.3
Organic matter content--1 to 3 percent
Thickness--28 to 75 cm
BC horizon
Moist color--7.5YR 5/4, 10YR 5/3, 10YR 5/4, 10YR 7/2, 10YR 7/3
Dry color--10YR 7/3, 10YR 7/4, 10YR 8/1, 10YR 8/2, 10YR 8/3
Fine-earth texture--ashy silt loam
Clay content--0 to 6 percent
Reaction--6.1 to 7.3
Organic carbon content--0.5 to 2.5 percent
Thickness--23 to 80 cm
2ABb horizon
Moist color--7.5YR 3/3, 7.5YR 3/4, 7.5YR 4/3, 10YR 4/3
Dry color--7.5YR 4/4, 7.5YR 5/3, 7.5YR 5/4, 7.5YR 6/3, 10YR 5/3, 10YR 6/3
Fine-earth texture--silt loam, loam
Clay content--12 to 27 percent
Total rock fragment content--0 to 5 percent
Gravel content--0 to 5 percent
Reaction--6.1 to 7.3
Organic matter content--1.0 to 3.5 percent
COMPETING SERIES:
Rathdrum--solum 45 to 100 cm thick; Bw horizon at mineral soil surface; 2C horizon directly below volcanic ash mantle; 2 to 6 percent clay and average of more than 5 percent rock fragments in 2C horizon (non-ash material)
GEOGRAPHIC SETTING:
Elevation--1320 to 1480 m
Climate--cold, wet winters; warm, moist summers
Mean annual precipitation--620 to 740 mm
Mean annual air temperature--5 to 7 degrees C
Frost-free period--40 to 110 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Tovame (T)--on low terraces of wide mountain valley floors; more than 150 cm (very deep) to bedrock; mollic epipedon; no ash recognized
Melloe (T)--on flood plains of mountain valley floors; more than 150 cm (very deep) to bedrock; mollic epipedon; no ash recognized; more than 35 percent rock fragments in particle-size control section
Bullroar--on high terraces and fans of mountain valley floors; more than 150 cm (very deep) to bedrock; more than 35 percent rock fragments in particle-size control section
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Saturation during normal years--none
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--moderately high
USE AND VEGETATION:
Use--timber production, watershed, wildlife habitat, recreation, livestock grazing
Potential native vegetation--grand fir, Douglas-fir, western larch, ponderosa pine, lodgepole pine, grouse huckleberry, pinegrass, white spirea, pinemat manzanita, elk sedge, heartleaf arnica
DISTRIBUTION AND EXTENT: Central Blue Mountains of northeastern Oregon; MLRA 10; small extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wallowa-Whitman National Forest, Oregon; 2012
REMARKS:
Diagnostic horizons and other features in this pedon
*Ochric epipedon
*Cambic horizon--zone from 41 to 114 cm
*Volcanic glass--zone from 10 to 137 cm
*Andic soil properties--zone from 10 to 137 cm
*Depth to lithologic discontinuity--137 cm
*Particle-size control section--zone from 10 to 110 cm
National Cooperative Soil Survey
U.S.A.