LOCATION SKELWA OR
Tentative Series
IRD. AGG/KLM/MPR
02/2025
SKELWA SERIES
Landscape--Eastern Cascade mountains
Landform--outwash plains
Slope--0 to 15 percent
Parent Material--volcanic ash mixed with outwash
Mean annual precipitation-- 670 mm
Mean annual air temperature-- 6 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-skeletal, glassy, frigid Humic Vitrixerands
TYPICAL PEDON: Skelwa ashy sandy loam, forested, on a 4 percent slope at an elevation of 1115 meters. (Colors are for dry soil unless otherwise noted.)
TYPE LOCATION: Deschutes County, Oregon; Latitude 44.2935940, Longitude -121.6634380, datum WGS84 (coordinates determine with a GPS).
Oi--0 to 3 centimeters; slightly decomposed plant material; strongly acid (pH 5.5); abrupt smooth boundary
A1--3 to 10 centimeters; ashy sandy loam, dark brown (10YR 3/3), very dark brown (10YR 2/2) moist; moderate medium granular structure; soft, very friable, nonsticky, nonplastic; common very fine roots and few coarse roots; many very fine and fine irregular pores; 2 percent fine rounded gravel and 2 percent subrounded gravel; neutral (pH 6.8); clear smooth boundary
A2--10 to 32 centimeters; ashy sandy loam, dark brown (10YR 3/3), very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; few medium and fine roots throughout; common very fine and fine irregular pores; 8 percent subrounded gravel; neutral (pH 6.9); clear smooth boundary
Bw--32 to 67 centimeters; very cobbly ashy sandy loam, dark yellowish brown (10YR 4/4), dark brown (10YR 3/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine, fine, medium, and coarse roots throughout; common very fine and fine irregular pores; 15 percent subrounded gravel, 20 percent subrounded and 20 percent rounded cobbles; neutral (pH 7.0); clear smooth boundary
BC--67 to 86 centimeters; extremely cobbly ashy sandy loam, yellowish brown (10YR 5/4), dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; few medium and coarse roots around fragments and common fine roots around fragments; few very fine and fine irregular pores; 5 percent subrounded gravel, 30 percent subrounded and 40 percent rounded cobbles; neutral (pH 7.0); gradual smooth boundary
C--86 to 200 centimeters; extremely cobbly ashy sandy loam, yellowish brown (10YR 5/4), dark yellowish brown (10YR 3/4) moist; single grain; loose, loose, nonsticky, nonplastic; few fine roots around fragments; few very fine irregular pores; 30 percent subrounded and 40 percent rounded cobbles, 10 percent rounded stones; neutral (pH 7.0)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature-- 7 degrees C
Soil moisture--usually moist in winter and spring, dry in the moisture control section for 60 to 90 days in the 4 months following the summer solstice
Thickness of mollic epipedon--18 to 40 cm
Thickness of cambic horizon--15 to 45 cm
Depth to outwash--30 to 80 cm
Reaction--6.1 to 7.3 (slightly acid to neutral)
Thickness of ash influenced layers--90 to 200 cm
Estimated properties of layers influenced by volcanic ash
*Ammonium oxalate extractable Al + Fe--0.4 to 1.0 percent
*1500 kPa water content (air dry)--less than 15 percent
*0.02 to 2.0 mm fraction--50 to 90 percent
*Volcanic glass in the 0.02 to 2.0 mm fraction--50 to 80 percent
*P retention--40 to 70 percent
Particle-size control section:
*Clay content, weighted average--2 to 15 percent
*Rock fragment content, weighted average--35 to 80 percent
A horizons
*Value--2 or 3
*Chroma--1 to 3
*Fine earth texture--ashy sandy loam, ashy loamy sand
*Clay--2 to 15 percent
*Sand--50 to 90 percent
*Organic matter--1.5 to 4 percent
*Total rock fragment content--2 to 40 percent
*Gravel--2 to 3 percent
*Cobble--0 to 5 percent
*Reaction--6.1 to 7.3 (slightly acid to neutral)
*Thickness--combined thickness of A horizons between 18 and 50 cm
Bw horizon
*Value--3 to 5
*Chroma--3 to 6
*Fine earth texture--ashy sandy loam, ashy loamy sand
*Clay--2 to 15 percent
*Sand--50 to 90 percent
*Organic matter--0.25 to 1 percent
*Total rock fragment content--45 to 80 percent
*Gravel--0 to 35 percent
*Cobble--0 to 45 percent
*Stone--0 to 10 percent
*Reaction--6.1 to 7.3 (slightly acid to neutral)
* Thickness--thickness of Bw horizon between 20 and 40 cm
BC horizon
*Value--3 to 5 moist, 4 to 6 dry
*Chroma--3 to 6
*Fine earth texture--ashy sandy loam, ashy loamy sand
*Clay--2 to 15 percent
*Sand--50 to 90 percent
*Organic matter--0.25 to 1 percent
*Total rock fragment content--45 to 80 percent
*Gravel--0 to 35 percent
*Cobble--35 to 60 percent
*Stone--0 to 10 percent
*Reaction--6.6 to 7.3 (neutral)
* Thickness--thickness of BC horizon between 15 and 30 cm
C horizon
*Value--3 to 6 moist, 4 to 8 dry
*Chroma--3 to 6 moist, 4 to 8 dry
*Fine earth texture--ashy sandy loam, ashy loamy sand, ashy loamy coarse sand
*Clay--2 to 15 percent
*Sand--50 to 90 percent
*Organic matter--0.1 to 0.50 percent
*Total rock fragment content--65 to 85 percent
*Gravel--0 to 35 percent
*Cobble--35 to 80 percent
*Stone--0 to 15 percent
*Reaction--6.6 to 7.3 (neutral)
* Thickness--thickness of C horizon between 50 and 115 cm
COMPETING SERIES:
Fryrear--50 to 100 cm to lithic contact; dry for 90 to 110 days following the summer solstice
Pipp--100 to 150 cm to lithic contact; dry for 45 to 60 days following the summer solstice
Silentcone--50 to 100 cm to lithic contact; dry for 90 to 110 days following the summer solstice; gravel sized cinders throughout the profile
Summertown--50 to 100 cm to densic contact; loamy coarse sand apparent textures throughout the profile; dry for about 90 days following the summer solstice
Yapoah--colluvial flagstones throughout the particle size control section; reaction is neutral throughout; no cambic horizon or lithologic discontinuity
Sanagon--dry for 45 to 60 days following the summer solstice
GEOGRAPHIC SETTING:
Elevation--950 to 1500 meters
Slope--0 to 15 percent
Climate--cool, wet winters and warm, dry summers
Mean annual precipitation--350 to 1000 mm
Mean annual air temperature--5 to 7 degrees C
Frost-free period--50 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Lundgren--occurs on outwash plains; less than 35 percent rock fragments in the particle size control section; dry for 90 to 110 days following the summer solstice
Wanoga--occurs on lava plains; 50 to 100 cm deep to a paralithic or lithic contact; dry for 90 to 110 days following the summer solstice
Dryache--occurs on moraines; less than 35 percent fragments in the particle size control section; dry for 45 to 60 days following the summer solstice
Sanagon--occurs on moraines; dry for 45 to 60 days following the summer solstice
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage--well drained
Saturated hydraulic conductivity (Ksat)--high to very high in all horizons
USE AND VEGETATION:
Use--timber production, wildlife habitat, recreation
Vegetation-- ponderosa pine, incense cedar, antelope bitterbrush, greenleaf manzanita, Idaho fescue, Ross' sedge; where precipitation is above 510 mm Douglas-fir, grand fir, white fir, pinegrass, long-stolon sedge, snowbrush ceanothus, western brackenfern
DISTRIBUTION AND EXTENT:
East slopes of the Cascade Mountains in central Oregon; MLRA 6; minor extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE:Bozeman, Montana
SERIES PROPOSED:
Deschutes County, Deschutes National Forest, Oregon 2023
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
*Particle-size control section--3 to 103 cm
*Mollic epipedon--3 to 32 cm
*Cambic horizon--32 to 67 cm
*Andic soil properties--3 to 200 cm
National Cooperative Soil Survey
U.S.A.