LOCATION SHARPRIDGE              OR

Tentative Series
IRD. JLW/RJO/DAL
03/2013

SHARPRIDGE SERIES

The Sharpridge series consists of deep and very deep, well drained soils formed in a mantle of volcanic ash over colluvium weathered from tuff on mountain footslopes and backslopes. Slope gradients are 5 to 60 percent. Mean annual precipitation is about 24 inches and mean annual temperature about 41 degrees F.

TAXONOMIC CLASS: Ashy over clayey, amorphic over smectitic, frigid Alfic Vitrixerands

TYPICAL PEDON: Sharpridge ashy silt loam - woodland, on a 26 percent north-facing slope at an elevation of 4,280 feet. (Colors are for moist soil unless otherwise noted. Soil textures are apparent field textures.)

Oi--0 to 1 inch; slightly decomposed needles, twigs, and logs

A--1 to 6 inches; black (7.5YR 2.5/1) ashy silt loam, brown (7.5YR 5/3) dry; weak very fine subangular blocky structure; soft, very friable, nonsticky, nonplastic and weakly smeary; common very fine and fine roots; common very fine irregular pores; 2 percent gravel and 2 percent cobbles; slightly acid (pH 6.5); clear wavy boundary. (4 to 8 inches thick)

Bw--6 to 16 inches; dark brown (7.5YR 3/2) ashy silt loam, light brown (7.5YR 6/3) dry; weak fine and medium subangular blocky structure; soft, friable, nonsticky, nonplastic and weakly smeary; common very fine and fine and few medium roots; common very fine irregular and few very fine tubular pores; 5 percent gravel, and 2 percent cobbles; slightly acid (pH 6.5); clear wavy boundary. (6 to 14 inches thick)

2Eb--16 to 21 inches; brown (7.5YR 4/3) loam, light brown (7.5YR 6/4) dry; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine and medium roots; common very fine irregular and tubular pores; 5 percent gravel, and 5 percent cobbles; neutral (pH 6.8); abrupt wavy boundary. (3 to 5 inches thick)

2Btb--21 to 42 inches; brown (7.5YR 4/3) clay, brown (7.5YR 5/4) dry; strong medium subangular blocky structure; very hard, very firm, very sticky and very plastic; many prominent clay films on ped faces; few very fine and fine roots; few very fine irregular pores; 5 percent gravel; neutral (pH 6.6); (10 to 26 inches thick)

2R--42 inches; tuff

TYPE LOCATION: Grant County, Oregon
Section 23 (NW , SE , SE ), T. 10 S., R. 32 E.
Latitude: 44 degrees, 40 minutes, 47 seconds, north
Longitude: 118 degrees, 49 minutes, 20 seconds, west
UTM coordinates: Zone 11; 4,948,770 northing; 355,570 easting; NAD 27
USGS Quadrangle: Susanville

RANGE IN CHARACTERISTICS:
Soil Temperature: frigid regime
Mean Annual Soil Temperature: 41 to 44 degrees F
Mean Summer Soil Temperature: 49 to 53 degrees F
Mean Winter Soil Temperature: 34 to 37 degrees F
Soil Moisture: xeric regime, dry 45 to 60 consecutive days in summer

Particle-size Control Section: mineral surface to 40 inches below the mineral soil surface
Upper part (ashy): 14 to 18 inches thick
Clay content, average: 4 to 12 percent
Rock fragment content, average: 0 to 15 percent
Lower part (clayey): 22 to 26 inches thick
Clay content, average: 35 to 45 percent
Rock fragment content, average: 5 to 25 percent

Diagnostic Horizons and Features:
andic soil properties: upper boundary at the mineral surface; 14 to 18 inches thick
Al+1/2Fe(aox): 1.0 to 2.5 percent
bulk density: 0.65 to 1.00 g/cc
P retention: 40 to 90 percent
0.02-2.0 mm fraction: 40 to 60 percent of fine earth
glass content in the 0.2 to 2.0mm fraction: 60 to 90 percent
water content at 1500 kPa (air dried): 5 to 12 percent
8Si + 2Fe (aox): 5 to 8 percent with 8Si being more than twice the 2Fe (amorphic)
ochric epipedon: 4 to 8 inches thick
cambic horizon: 6 to 14 inches thick
argillic horizon: 10 to 26 inches thick
lithic contact, depth to: 40 to 80 inches

A horizon:
color, moist: 5YR 3/1; 7.5YR 2.5/1, 2.5/3, 3/2; 10YR 2/2
color, dry: 7.5YR 5/3, 6/2; 10YR 5/2, 5/3
texture: ASHY-SIL, GR-ASHY-SIL, ST-ASHY-SIL
clay content: 4 to 12 percent
rock fragment content: 0 to 20 percent
gravel: 0 to 15 percent
cobbles: 0 to 5 percent
stones: 0 to 15 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
base saturation: 45 to 60 percent (by the sum of bases)
organic carbon: 1 to 5 percent

Bw horizon:
color, moist: 7.5YR 3/2, 3/3; 10YR 3/3
color, dry: 7.5YR 6/2, 6/3; 10YR 5/4, 6/4
texture: ASHY-SIL, GR-ASHY-SIL, ST-ASHY-SIL
clay content: 4 to 12 percent
rock fragment content: 0 to 25 percent
gravel: 0 to 15 percent
cobbles: 0 to 5 percent
stones: 0 to 20 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
base saturation: 45 to 60 percent (by the sum of bases)
organic carbon: 0.6 to 1.0 percent

2Eb horizon: (also horizonated as 2Bwb, 2Ab)
color, moist: 7.5YR 3/4, 4/3; 10YR 4/3
color, dry: 7.5YR 5/3, 6/3, 6/4; 10YR 5/4, 6/3
texture: CL, L, SCL, CB-CL, GR-CL, STV-L
clay content: 18 to 35 percent
rock fragment content: 10 to 45 percent
gravel: 10 to 20 percent
cobbles: 0 to 20 percent
stones: 0 to 25 percent
reaction: slightly acid to neutral; pH: 6.1 to 7.3
base saturation: 60 to 75 percent (by the sum of bases)

2Btb horizon:
color, moist: 2.5YR 3/2; 7.5YR 4/2, 4/3; 10YR 3/3, 5/3
color, dry: 5YR 5/2; 7.5YR 4/2, 4/3, 5/4; 10YR 5/3, 6/3
texture: C, CB-C, GR-C, GR-SIC, ST-SIC
clay content: 40 to 55 percent
rock fragment content: 5 to 25 percent
gravel: 2 to 15 percent
cobbles: 0 to 15 percent
stones: 0 to 15
reaction: slightly acid to neutral; pH: 6.1 to 7.3
base saturation: 75 to 85 percent (by the sum of bases)
organic carbon: 0.0 to 1.2 percent

2BC horizon with 25 to 35 percent clay, present in some pedons

COMPETING SERIES: there are no competing series in the same family
Boardtree: has glassy family mineralogy and is continuously dry 60 to 75 days in summer

GEOGRAPHIC SETTING:
Landform: mountain backslopes and footslopes
Slope gradient: 5 to 60 percent
Parent material: volcaniclastic volcanic ash over colluvium
Lithology: Mazama ash over clay-forming tuff
Elevation: 4,200 to 5,200 feet
Climate: cold, wet winters and cool, dry summers
Mean annual precipitation: 21 to 26 inches
Mean annual air temperature: 39 to 42 degrees F
Frost-free period: 40 to 80 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Meaufun: on mountain backslopes with a mollic epipedon of ash mixed with colluvium, a fine particle-size class family, under Douglas fir and ponderosa pine forest;
Humarel: clayey-skeletal, moderately deep soil on eroding backslopes of andesitic tuff breccia mudflow deposits with a minor influence of volcanic ash;
Tolo: on benches, backslopes and toe slopes of dissected plateaus with thick ash mantle and loamy-skeletal subsoil under Douglas fir, grand fir and lodgepole pine forest;
Hafmau: clayey-skeletal, shallow soil to a lithic contact on rolling mountain sideslopes and benches.

DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderate in ash mantle and slow in subsoil

USE AND VEGETATION:
Use: woodland, watershed, wildlife, recreation, range
Native vegetation: grand fir, Douglas fir, lodgepole pine, western larch, ponderosa pine, grouse huckleberry, darkwoods violet, woods strawberry, heartleaf arnica, pinegrass, elk sedge, and western fescue.
Plant Association: Dominant: ABGR/VASC (grand fir/grouse huckleberry); may include: PICO(ABGR)/VASC (lodgepole pine- grand fir/grouse huckleberry) or ABGR/SPBE (grand fir/birchleaf spiraea)

DISTRIBUTION AND EXTENT:
Distribution: Central Blue Mountains of northeastern Oregon; MLRA 10
Extent: small

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES PROPOSED: Malheur National Forest, Oregon 2007. Name is from a mountain ridge.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon: 1 to 6 inches; A
cambic horizon: 6 to 16 inches; Bw
argillic layer: 21 to 42 inches; 2Btb
particle-size control section:
ashy part: 1 to 16 inches; A, Bw
clayey part: 16 to 42 inches; 2Eb, 2Btb
lithic contact: 42 inches; 2R

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National Cooperative Soil Survey
U.S.A.