LOCATION COMBSFLAT ORTentative Series
TAXONOMIC CLASS: ashy over clayey, glassy over smectitic, frigid Alfic Humic Vitrixerands
TYPICAL PEDON: Combsflat ashy sandy loam -upland forest, on a 20 percent concave east facing slope at elevation of 5,300 feet located in the Maury Mountains, Crook County, Oregon. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch, slightly decomposed forest litter
A1--1 to 5 inches, dark brown (10YR 3/3) ashy sandy loam, very dark brown (10YR 2/2) moist; strong thin to medium platy structure; soft, friable, nonsticky and nonplastic; many very fine and fine roots; many very fine and fine vesicular pores; 5 percent gravel; moderately acid (pH 5.8); abrupt smooth boundary.
A2--5 to 16 inches, dark brown (10YR 3/3) ashy sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and non-plastic; many very fine, fine, medium and coarse roots; many very fine and fine irregular pores; 5 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (Combined thickness of A horizons is 14 to 20 inches.)
2Btb1--16 to 30 inches; brown (10YR 4/3) clay, dark brown (10YR 3/3) moist; strong fine and medium prismatic stucture; hard, firm, moderately sticky and moderately plastic; many very fine and medium roots, and common coarse and very coarse roots; many very fine irregular pores and few fine continuous tubular pores; common distinct clay films on ped faces and in pores; 10 percent gravel; slightly acid (pH 6.4); clear smooth boundary.
2Btb2--30 to 50 inches; brown (10YR 4/3) gravelly sandy clay, dark brown (10YR 3/3) moist; weak fine and medium prismatic structure; hard, firm, slightly sticky, and moderately plastic; common very fine to medium roots; many very fine to fine irregular and tubular pores; many distinct clay films on ped faces and in pores; 30 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (Combined thickness of 2Btb horizon is 30 to 50 inches)
2BC--50 to 61 inches; brown (10YR 4/3) extremely cobbly sandy clay loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine to medium roots; few very fine and fine irregular and tubular pores; 25 percent gravel, 25 percent cobble and 10 percent stones; slightly acid (pH 6.4).
TYPE LOCATION: Crook County, Oregon,
SE 1/4 of Sec. 11, T. 18 S, R. 18E..
Latitude 44 degrees, 01 minutes, 13.69 seconds N
Longitude: 120 degrees, 31 minutes, 20.75 seconds
UTM Coordinates: Zone: 10, Northing: 4877140.5, Easting: 698565.1
RANGE IN CHARACTERISTICS:
Soil Temperature Regime: frigid
Mean Annual Soil Temperature: 37 to 41 degrees F.
Mean Summer Soil Temperature: 44 to 49 degrees F.
Mean Winter Soil Temperature: 32 to 36 degrees F.
Soil Moisture Regime: xeric; dry 60 to 90 consecutive days in summer and early fall
Particle-size Control Section: mineral surface to 40 inches below mineral surface.
Upper part (ashy): 14 to 20 inches thick
Clay content (weighted average): 7 to 18 percent
Rock fragment content (weighted average): 5 to 10 percent
Lower part (clayey):
Clay content (weighted average): 35 to 60 percent
Rock fragment content (weighted average): 10 to 35 percent
Diagnostic horizons and features:
Andic soil properties: upper boundary at the mineral surface, 14 to 20 inches thick
Al +1/2 Fe (aox): 0.4 to 0.8 percent
P Retention: 25 to 50 percent
0.2 to 2.0 mm fraction: 60 to 80 percent of fine earth
volcanic glass in 0.2 to 2.0 mm fraction: 30 to 60 percent
water content at 1500 kPa (air dry): 8 to 12 percent
mollic epipedon: 14 to 20 inches thick
argillic horizon: 30 to 50 inches thick
lithic contact: over 60 inches
Major horizons:
A horizon
color, moist: 10YR 2/1, 2/2
color, dry: 10YR 3/2, 3/3, 4/2, 4/3
rock fragments: 5 to 10 percent
gravel: 0 to 5 percent
cobbles: 0 to 5 percent
stones: 0 to 5 percent
boulders: 0 to 5 percent
reaction: slightly to moderately acid; pH: 5.6 to 6.5
2Btb horizon
color, moist: 10YR 2/1, 2/2
color, dry: 10YR 3/2, 3/3, 4/2, 4/3
texture: clay or sandy clay
texture modifier: gravelly, cobbly
clay content: 35 to 60 percent
rock fragments: 15 to 35 percent
gravel: 10 to 30 percent
cobbles: 0 to 15 percent
stones: 0 to 5 percent
boulders: 0 to 5 percent
reaction: moderately acid to neutral; pH 5.6 to 7.3
base saturation (sum): 75 to 100 percent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform: In depressions and on benches on mountains and hills
Slope gradient: 5 to 40 percent
Parent material: volcanic ash over colluvium from rhyolite and basalt
Elevation: 4,000 to 6,000 feet
Climate: cold, wet winters and hot, dry summers
Mean annual precipitation: 18 to 24 inches
Mean annual temperature: 40 to 45 degrees F.
Frost-free period: 60 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Maule (T) - soils occur on plateau tops and mountain sideslopes; mineral soil is 20 to 40 inches deep to bedrock
Sintuf (T) - soils occur on plateau tops, ridges, rolling sideslopes; mineral soil is less than 20 inches deep to bedrock
DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: rapid in ashy layers and slow in clayey subsoil
USE AND VEGETATION:
Use: timber production, livestock grazing, wildlife habitat, and water supply.
Natural vegetation: ponderosa pine and elk sedge.
DISTRIBUTION AND EXTENT:
Distribution--Central Oregon
MLRA--43c Blue Mountains-Seven Devils
Extent--Moderate
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Crook County, Oregon; 2005
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Andic soil material (ash) 1 to 16 inches A1, A2
Mollic epipedon 1 to 16 inches A1, A2
Argillic horizon 16 to 50 inches 2Btb1, 2Btb2 .
Ecological site: moist pine and dry Douglas fir plant association groups.