LOCATION TEPEH                   WA

Established Series
Rev. TMR/SBC
06/2011

TEPEH SERIES

The Tepeh series consists of very deep, well drained soils formed in volcanic ash overlying glacial drift and colluvium. Tepeh soils are on slopes of 25 to 100 percent on debris aprons, debris cones, and valley walls of glaciated mountain landscapes. The mean annual precipitation is about 1,900 millimeters and the mean annual air temperature is about 5 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, isotic Andic Dystrocryepts

TYPICAL PEDON: Tepeh ashy sandy loam, with approximately 10 percent of the soil surface covered with subangular cobbles, located on a forested southeast facing valley wall with a slope of 55 percent and an elevation of 1,700 meters. When described on September 18, 2007 the soil was slightly moist throughout. (Colors are for moist soil unless otherwise noted)

Oi--0 to 2 cm; slightly decomposed twigs, needles, and leaves; abrupt smooth boundary.

Oe--2 to 5 cm; dark brown (7.5YR 3/2) moderately decomposed twigs and needles, brown (7.5YR 5/2) dry; many very fine to fine and few medium to coarse roots; common medium interstitial pores; very strongly acid (pH 4.5); abrupt smooth boundary.

E--5 to 8 cm; very dark grayish brown (10YR 3/2) ashy sandy loam, grayish brown (10YR 5/2) dry; weak medium granular structure; soft, very friable, nonsticky, nonplastic; many very fine to fine, common medium, and few coarse roots at top of horizon; common fine interstitial pores; 5 percent gravel and 5 percent cobbles; very strongly acid (pH 4.5); abrupt wavy boundary.

Bw1--8 to 30 cm; dark yellowish brown (10YR 4/4) gravelly ashy sandy loam, light yellowish brown (10YR 6/4) dry; moderate medium subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common very fine to medium and few coarse to very coarse roots; common fine to medium irregular pores; 10 percent fine gravel, 15 percent medium and coarse gravel, and 5 percent cobbles; very strongly acid (pH 4.8); clear wavy boundary.

2Bw2--30 to 70 cm; dark yellowish brown (10YR 3/4) very gravelly sandy loam, brown (10YR 4/3) dry; moderate medium subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; few very fine to medium roots; common fine to medium irregular pores; 10 percent fine gravel, 25 percent medium and coarse gravel, 10 percent cobbles, and 5 percent stones; strongly acid (pH 5.1); clear wavy boundary.

2Bw3--70 to 92 cm; dark yellowish brown (10YR 3/4) very gravelly sandy loam, brown (10YR 4/3) dry; single grain; loose, nonsticky, nonplastic; few very fine to fine roots; common medium to coarse interstitial pores; 10 percent fine gravel, 25 percent medium and coarse gravel, 15 percent cobbles, and 5 percent stones; strongly acid (pH 5.2); abrupt wavy boundary.

2BC--92 to 152 cm; olive brown (2.5Y 4/3) extremely cobbly loamy sand, light yellowish brown (2.5Y 6/3) dry; single grain; loose, nonsticky, nonplastic; few fine roots; many coarse interstitial pores; 15 percent fine gravel, 30 percent medium and coarse gravel, 20 percent cobbles, and 10 percent stones; moderately acid (pH 5.8).

TYPE LOCATION: Chelan County, Washington, approximately 12 km north of the town of Stehekin; North Cascades National Park Service Complex, below McAlester Pass. 15 meters west and 700 meters north of the southeast corner of section 25, T. 34 N., R. 17 E. Willamette Meridian; McAlester Mountain, Washington USGS quadrangle; 48 degrees, 25 minutes, 3 seconds north latitude and 120 degrees, 39 minutes, 58 seconds west longitude; UTM 672670 meters E, 5365340 meters N, zone 10N.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 4 to 8 degrees C. Cryic soil temperature regime.
Moisture control section - dry less than 30 consecutive days. Udic soil moisture regime.
Particle-size control section:
Clay content - 0 to 10 percent
Rock fragments - 35 to 75 percent total, 15 to 65 percent fine to coarse gravel, 10 to 30 percent cobbles, 0 to 30 percent stones
Thickness of volcanic ash mantle (ashy textural modifier): 18 to 35 centimeters

A horizons are sometimes present in place of the topmost E or Bw horizon, with thickness ranging from 2 to 20 cm, textures of ashy SL or ashy FSL, reaction of very strongly acid to strongly acid, hue of 7.5YR or 10YR, moist value of 2 to 3, and moist chroma of 1 to 3.

E horizon
Hue - 10YR or 7.5YR
Value - 3 to 4 moist, 4 to 5 dry
Chroma - 1 or 2 moist or dry
Fine earth texture - ashy SL or ashy FSL
Rock fragments - 0 to 15 percent fine to coarse gravel
Volcanic glass - 35 to 80 percent
Reaction - extremely acid to very strongly acid
Thickness - 0 to 5 centimeters (may not be present in all pedons)

Bw horizon
Hue - 10YR or 7.5YR
Value - 3 to 5 moist, 4 to 6 dry
Chroma - 2 to 4 moist or dry
Fine earth texture - ashy SL or ashy FSL
Rock fragments - 15 to 55 percent total, 15 to 55 percent gravel, 0 to 15 percent cobbles, 0 to 10 percent stones
Volcanic glass - 15 to 70 percent
Reaction - very strongly acid to strongly acid
Thickness - 15 to 35 centimeters

2Bw horizons
Hue - 10YR or 2.5Y
Value - 3 to 5 moist, 4 to 6 dry
Chroma - 2 to 4 moist or dry
Fine earth texture - SL, COSL, LFS
Rock fragments - 35 to 75 percent total, 25 to 55 percent gravel, 10 to 25 percent cobbles, 0 to 25 percent stones
Volcanic glass - 5 to 15 percent
Reaction - moderately acid to strongly acid
Combined thickness - 30 to 80 centimeters

2BC horizon
Hue - 2.5Y or 10YR
Value - 4 to 5 moist, 5 to 6 dry
Chroma - 2 to 4 moist or dry
Fine earth texture - LS, COSL, SL, or LFS
Rock fragments - 35 to 75 percent total, 25 to 55 percent gravel, 10 to 25 percent cobbles, 0 to 25 percent stones
Volcanic glass - 0 to 5 percent
Reaction - moderately acid to strongly acid

COMPETING SERIES: These are the Angelbasin, McCay, Prouty, Skinwood, Smokejump, Twentymile, and Venson series. Angelbasin, Skinwood, Smokejump, and Venson soils are all moderately deep (50 to 100 cm) to a lithic contact. McCay soils are deep (100 to 150 cm) to a paralithic contact. Prouty soils are moderately deep (50 to 100 cm) to a paralithic contact. Twentymile soils are moderately deep (50 to 89 cm) to a densic contact with dense glacial till.

GEOGRAPHIC SETTING: Tepeh soils are on slopes of 25 to 100 percent on debris aprons, debris cones, and valley walls of glaciated mountain landscapes at elevations from 800 to 2,000 meters. They formed in volcanic ash overlying glacial drift and colluvium from glacial drift. The climate is characterized by cool, dry summers and cold, wet winters. Mean annual precipitation ranges from 1,500 to 3,300 millimeters. Mean annual air temperature ranges from 2 to 8 degrees C. Frost-free season is 30 to 60 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Doubtful, Perfect, Spickard, and Stetattle soils. Doubtful soils are moderately deep (50 to 100 cm) to a lithic contact. Perfect soils have a sandy-skeletal particle-size control section and vitrandic soil properties through a majority of the control section. Spickard soils have a contrasting particle-size control section and andic soil material greater than 35 cm thick. Stetattle soils have a pachic umbric epipedon.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high to very high saturated hydraulic conductivity.

USE AND VEGETATION: Tepeh soils support wildlife habitat, recreation, and watershed drainage. Native vegetation includes Pacific silver fir, western hemlock, mountain hemlock, and occasionally Engelmann spruce and Alaska yellow cedar. Understory species include big huckleberry, Cascade azalea, lady fern, broadleaf lupine, and fringecup.

DISTRIBUTION AND EXTENT: North Cascade Mountains, Washington. MLRA 3. Series is of small extent.

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

SERIES ESTABLISHED: North Cascades National Park Service Complex, Chelan County, Washington, 2011.

REMARKS: Diagnostic horizons and features recognized in this pedon include:
Particle-size control section - 30 to 105 cm (25 to 100 cm from the mineral surface)
Ochric epipedon - 0 to 18 cm (Oi, Oe, E, and upper 10 cm of the Bw1 horizon)
Andic soil properties - 5 to 30 cm (E and Bw1 horizons)
Cambic horizon - 8 to 92 cm (Bw1, 2Bw2, and 2Bw3 horizons)
Lithologic discontinuity - 30 centimeters

ADDITIONAL DATA: NSSL lab pedon number 06N0799, NSSL user pedon ID S06WA057002.

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National Cooperative Soil Survey
U.S.A.