LOCATION COTAY                   OR

Established Series
Rev. JLW/RAW/DAL
07/2016

COTAY SERIES

The Cotay series consists of moderately deep, well-drained soils on backslopes of mountains. Cotay soils formed in volcanic ash mixed with colluvium overlying fractured metavolcanic bedrock. Slopes are 0 to 90 percent. Mean annual precipitation is about 33 inches and mean annual temperature about 40 degrees F.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Vitrandic Haploxeralfs

TYPICAL PEDON: Cotay gravelly ashy silt loam forested, on a 25 percent southwestfacing slope at an elevation of 5,220 feet. (Colors are for moist soil unless otherwise noted. Andic soil materials are apparent field textures.)

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

Oe--1 to 2 inches; moderately decomposed forest litter

A--2 to 5 inches; dark brown (7.5YR 3/3) gravelly ashy silt loam, light brown (7.5YR 6/3) dry; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and few medium roots; few fine irregular pores; 10 percent gravel and 5 percent cobbles; neutral (pH 6.7); clear wavy boundary. (2 to 5 inches thick)

Bw--5 to 14 inches; reddish brown (5YR 4/3) cobbly ashy silt loam, light brown (7.5YR 6/4) dry; weak fine and very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine, fine, medium, and coarse roots; few fine tubular and few fine irregular pores; 15 percent gravel and 10 percent cobbles; slightly acid (pH 6.2); clear wavy boundary. (6 to 11 inches thick)

2Eb--14 to 21 inches; brown (7.5YR 5/4) very cobbly clay loam, light brown (7.5YR 6/4) dry; weak medium subangular blocky structure parting to moderate fine and very fine subangular blocky; hard, friable, moderately sticky and moderately plastic; common very fine, fine, medium, and few coarse roots; common very fine and few fine tubular pores; 25 percent gravel and 15 percent cobbles; neutral (pH 7.0); clear irregular boundary. (2 to 11 inches thick)

2Btb1--21 to 28 inches; brown (7.5YR 4/4) very cobbly clay loam, light brown (7.5YR 6/4) dry; weak medium subangular blocky structure grading to moderate fine subangular blocky; hard, firm, moderately sticky and moderately plastic; many thin clay films on ped faces; common fine and medium roots; few very fine tubular pores; 30 percent gravel, 20 percent cobbles and 5 percent stones; neutral (pH 7.3); gradual smooth boundary. (6 to 22 inches thick)

2Btb2--28 to 41 inches; reddish brown (5YR 4/3) extremely cobbly clay, brown (7.5YR 5/4) dry, moderate medium subangular blocky structure grading to moderate fine subangular and moderate very fine angular blocky; very hard, firm, very sticky and very plastic; many thin and common moderately thick clay films on ped faces; few fine and medium roots, few very fine tubular pores; 35 percent gravel, 25 percent cobbles, and 5 percent stones; slightly alkaline (pH 7.5); abrupt irregular to wavy boundary. (0 to 11 inches thick)

2R--41 inches; hard fractured metavolcanic bedrock

TYPE LOCATION: Grant County, Oregon
Section 36 (SE1/4, SW1/4, NE1/4), T. 10 S., R. 34 E.
Latitude: 44 degrees, 40 minutes, 34 seconds N.
Longitude: 118 degrees, 33 minutes, 35 seconds W.
UTM coordinates: zone 11; north 4947937.8 meters, east 376375.6 meters NAD27
USGS Quadrangle: Vinegar Hill

RANGE IN CHARACTERISTICS:
Soil Temperature: frigid regime
Mean Annual Soil Temperature: 40 to 45 degrees F
Mean Summer Soil Temperature: 48 to 53 degrees F
Mean Winter Soil Temperature: 32 to 37 degrees F
Soil Moisture: xeric regime, dry 45 to 60 consecutive days in summer

Particle-size Control Section: upper 20 inches of argillic horizon or from the top of argillic to the lithic contact if less than 20 inches
clay content, average: 35 to 40 percent
rock fragment content, average: 35 to 80 percent

Diagnostic Horizons and Features:
vitrandic subgroup properties: upper boundary at the mineral surface; 7 to 13 inches thick
Al+1/2Fe (ammonium oxalate): 0.2 to 0.8 percent
P retention: 20 to 45 percent
0.02-2.0 mm fraction: 30 to 40 percent of fine earth
glass content in the 0.02-2.0mm fraction: 15 to 30 percent
cambic horizon: 6 to 11 inches thick
eluvial horizon, buried: 2 to 11 inches thick
argillic horizon, buried: 13 to 22 inches thick
lithic contact, depth below mineral soil surface: 20 to 40 inches

A horizon:
color, moist: 5YR 2.5/1, 3/3; 7.5YR 2.5/2, 3/2, 3/3
color, dry: 5YR 5/3; 7.5YR 4/2, 5/3, 6/3, 6/4; 10YR 5/3
texture: ASHY-SIL, GR-ASHY-SIL
clay content: 4 to 18 percent
rock fragment content: 0 to 30 percent total
gravel: 0 to 25 percent
cobbles: 0 to 5 percent
reaction: moderately acid to neutral; pH: 5.6 to 7.3

Bw horizon:
color, moist: 5YR 4/3; 7.5YR 3/4
color, dry: 5YR 6/3; 7.5YR 6/4; 10YR 6/5
texture: GR-ASHY-SIL, CB-ASHY-SIL, ASHY-SIL, ASHY-L
clay content: 6 to 22 percent
rock fragment content: 10 to 30 percent total
gravel: 5 to 30 percent
cobbles: 0 to 10 percent
stones: 0 to 5 percent
boulders: 0 to 5 percent
reaction: moderately acid to neutral; pH: 5.6 to 7.3

2Eb horizon:
color, moist: 7.5YR 4/2, 4/3, 4/4, 5/4; 10YR 5/4
color, dry: 7.5YR 6/2, 6/4; 10YR 5/3, 6/4, 7/3, 7/4
texture: GR-CL, GRV-L, GRV-CL, CBV-CL
clay content: 22 to 35 percent
rock fragment content: 30 to 45 percent
gravel: 20 to 40 percent
cobbles: 0 to 15 percent
stones: 0 to 5 percent
boulders: 0 to 5 percent
reaction: neutral to slightly alkaline; pH: 6.6 to 7.8

2Btb1 horizon:
color, moist: 7.5YR 4/2, 4/3, 4/4; 10YR 4/3, 4/4
color, dry: 7.5YR 5/2, 6/4; 10YR 5/4, 6/3, 7/3
texture: CBV-CL, GRV-CL, GRX-CL, GRV-C
clay content: 32 to 40 percent
rock fragment content: 40 to 80 percent total
gravel: 25 to 75 percent
cobbles: 0 to 20 percent
stones: 0 to 10 percent
boulders: 0 to 5 percent
reaction: neutral to slightly alkaline; pH: 6.6 to 7.8

2Btb2 horizon:
color, moist: 5YR 4/3; 7.5YR 4/2, 4/3; 10YR 4/4; 2.5YR 5/3
color, dry: 7.5YR 5/2, 5/4; 10YR 5/3, 6/4; 2.5Y 6/3
texture: GRX-CL, GRV-C, CBV-C
clay content: 35 to 45 percent
rock fragment content: 25 to 85 percent total
gravel: 10 to 85 percent
cobbles: 0 to 20 percent
stones: 0 to 5 percent
reaction: neutral to slightly alkaline; pH: 6.6 to 7.8

COMPETING SERIES:
Cougarrock: moderately deep (20 to 40 inches) to a lithic contact (soft tuffs or basalt); cambic (Bw) is silt loam with 10 to 22 percent clay; have a buried eluvial (2Eb) horizon; have paralithic material (soft rock) 3 to 10 inches thick above lithic contact
Dunstan: deep (40 to 60 inches) to a lithic contact (andesitic tuff breccia)
Stithum: very deep (lacks a lithic contact within 60 inches) in alluvium (mixed lithology); do not have a cambic (Bw) horizon; dry 60 to 75 consecutive days in summer
Tamarackcanyon: moderately deep (20 to 40 inches) to a lithic contact (basalt); cambic (Bw) is clay loam or silty clay loam with 25 to 35 percent clay; do not have an eluvial (2Eb) horizon

GEOGRAPHIC SETTING:
Landform: surface eroding and mass failure prone backslopes of uplifted and tilted blocks of metavolcanic rocks in exotic terranes.
Slope gradient: 0 to 90 percent
Parent material: Mazama volcanic ash and colluvium overlying residual materials
Lithology: metavolcanics
Elevation: 4,000 to 6,000 feet
Climate: cold, wet winters; warm, dry summers
Mean annual precipitation: 27 to 38 inches
Mean annual air temperature: 37 to 43 degrees F.
Frost-free period: 30 to 80 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Blackgulch: on moderately dissected backslopes, shallow to bedrock with a mollic epipedon and minor influence of volcanic ash under ponderosa pine or Douglas-fir forest with elk sedge or common snowberry understory;
Humarel: on eroding backslopes of andesitic tuff breccia mudflow deposits; moderately deep to bedrock with an influence of volcanic ash, mollic epipedon and argillic horizon, under ponderosa pine, Douglas-fir, common snowberry and elk sedge
Lemoncreek: on eroding backslopes; moderately deep to metavolcanic bedrock with mixed mantle of ash and colluvium over loamy-skeletal colluvium; under grand fir forest with pinegrass or elk sedge in the understory
Payraise: on backslopes; in very deep colluvium with a thin volcanic ash mantle and loamy-skeletal argillic horizon under grand fir, pinegrass and birchleaf spiraea;
Slaughterhouse: on backslopes and summits, deep to bedrock with a thick volcanic ash mantle, an argillic horizon and 18 to 27 percent clay in the particle-size control section under grand fir forest;

DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderately rapid over slow

USE AND VEGETATION:
Use: Timber production, livestock grazing, wildlife, recreation, watershed.
Potential native vegetation: grand fir, Douglas-fir, ponderosa pine, pinemat manzanita, Oregongrape, birchleaf spiraea, common yarrow, white hawkweed, lupines, bracken fern, pinegrass, elk sedge and northwestern sedge.
Plant association: ABGR/CARU (grand fir/pinegrass); may include PSME/CARU (Douglas-fir/pinegrass) or ABGR/SPBE (grand fir/birchleaf spiraea).

DISTRIBUTION AND EXTENT:
Distribution: MLRA: 10; Central Rocky and Blue Mountain Foothills
Extent: small

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

SERIES ESTABLISHED: Wallowa-Whitman National Forests, Oregon, 2012

REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon: 2 to 5 inches; A
cambic horizon: 5 to 14 inches; Bw
eluvial horizon, buried: 14 to 21 inches; 2Eb
argillic horizon, buried: 21 to 41 inches; 2Btb1, 2Btb2
andic soil properties (mixed ash mantle): 2 to 14 inches; A, Bw
particle-size control section: 21 to 41 inches; 2Btb1, 2Btb2

07/2016: Removed serpentine from the parent material but some minor areas of Cotay may include serpentinite rock mixed in with the metavolcanics. Further field investations would be needed to identify this specific locations.

ADDITIONAL DATA: Laboratory data: National Soil Survey Laboratory, Lincoln, NE; pedon ID: 97OR023005, sampled as Cotay series

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National Cooperative Soil Survey
U.S.A.