LOCATION PRIMUS WA

Established Series
Rev. CAB/SBC
06/2011

PRIMUS SERIES

The Primus series consists of very deep, well drained soils formed in volcanic ash and reworked glacial drift on debris aprons, valley walls, and fan terraces. Slopes are 10 to 40 percent on debris aprons and valley walls and 5 to 15 percent on fan terraces. The mean annual precipitation is about 1,450 millimeters. The mean annual temperature is about 4 degrees C.

TAXONOMIC CLASS: Ashy over sandy or sandy-skeletal, glassy over isotic Xeric Vitricryands

TYPICAL PEDON: Primus gravelly ashy fine sandy loam, on a fan terrace landform with a south facing slope of 8 percent at 700 meters elevation under coniferous forest vegetation. When described on October 14, 2006 the soil was dry throughout. (Colors are for moist soil unless otherwise noted.)

Oi--0 to 1 cm; slightly decomposed plant material; abrupt smooth boundary.

Oe--1 to 3 cm; moderately decomposed plant material; abrupt smooth boundary.

Bw1--3 to 34 cm; dark yellowish brown (10YR 3/4) gravelly ashy fine sandy loam, yellowish brown (10YR 5/4) dry; moderate medium subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common very fine and fine and many medium and coarse roots throughout; 10 percent fine gravel, 15 percent medium and coarse gravel, and 5 percent cobbles; strongly acid (pH 5.5); clear wavy boundary.

Bw2--34 to 60 cm; dark yellowish brown (10YR 3/4) gravelly ashy fine sandy loam, yellowish brown (10YR 5/4) dry; moderate coarse subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common very fine, fine, medium, and coarse roots throughout; 10 percent fine gravel, 15 percent medium and coarse gravel, and 5 percent cobbles; moderately acid (pH 5.7); clear wavy boundary.

2BC--60 to 84 cm; dark yellowish brown (10YR 3/4) extremely cobbly ashy sandy loam, yellowish brown (10YR 5/4) dry; single grain; loose, nonsticky, nonplastic; common very fine, fine, medium, and coarse roots throughout; 15 percent fine gravel, 30 percent medium and coarse gravel, 25 percent cobbles, and 10 percent stones; moderately acid (pH 5.9); clear wavy boundary.

2C--84 to 150 cm; olive brown (2.5Y 4/4) extremely gravelly loamy sand, light olive brown (2.5Y 5/4) dry; single grain; loose, nonsticky, nonplastic; few very fine and fine roots throughout; 15 percent fine gravel, 35 percent medium and coarse gravel, 20 percent cobbles, and 5 percent stones; slightly acid (pH 6.1).

TYPE LOCATION: North Cascades National Park, Chelan County, Washington; 226 meters east and 318 meters north of SW corner of Section 19, T34N, R16E Willamette Meridian; Goode Mountain, Washington USGS quadrangle; 48 degrees 25 minutes 43 seconds north latitude, 120 degrees 54 minutes 49 seconds west longitude; NAD83; UTM 654329 meters E, 5366039 meters N, zone 10N.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 4 to 8 degrees C. Cryic soil temperature regime.
Soil moisture control section: dry for 45 to 60 consecutive days from June to October. Xeric soil moisture regime.
Thickness of volcanic ash mantle: 40 to 80 centimeters
The particle-size control section in this soil is contrasting. Most characteristics are listed by horizon.

A horizons are sometimes present with thickness ranging from 1 to 10 centimeters, textures of ashy SL or ashy FSL, reaction of very strongly acid or strongly acid, hue of 7.5YR or 10YR, moist value of 2 to 3, and moist chroma of 1 or 2.

Bw horizons:
Hue - 10 YR
Value - 3 to 5 moist, 4 to 6 dry
Chroma - 3 or 4 moist or dry
Fine earth texture - ashy FSL, ashy COSL, or ashy SL
Rock fragments - 0 to 30 percent total
0 to 30 percent gravel
0 to 15 percent cobbles
0 to 5 percent stones
Clay content - 3 to 8 percent
Volcanic glass - 20 to 60 percent
Reaction - strongly acid to moderately acid
Thickness - 35 to 70 centimeters

2BC horizon:
Hue -10YR
Value - 3 to 5 moist, 4 to 6 dry
Chroma - 3 or 4 moist or dry
Fine earth texture - ashy LS or ashy SL
Rock fragments - 25 to 85 percent total
15 to 45 percent gravel
10 to 60 percent cobbles
0 to 15 percent stones
Clay content - 1 to 6 percent
Volcanic glass - 5 to 30 percent
Reaction - moderately acid to slightly acid
Thickness - 10 to 30 centimeters

2C horizon:
Hue - 2.5Y or variegated
Value - 3 to 5 moist, 5 or 6 dry
Chroma - 3 or 4 moist or dry
Fine earth texture - LS or LCOS
Rock fragments - 35 to 85 percent total
15 to 60 percent gravel
10 to 60 percent cobbles
0 to 10 percent stones
Clay content - 0 to 6 percent
Volcanic glass - 0 to 20 percent
Reaction - moderately acid to slightly acid

COMPETING SERIES: These are Resner, Scar, and Tunkcreek soils. Resner soils have ashy loam and ashy silt loam textures in the upper part of the particle-size control section. Scar soils have an albic horizon and the lower part of the particle-size control section has less than 35 percent rock fragments. Tunkcreek soils have less than 35 percent rock fragments in the lower part of the particle-size control section and are dry for 60 to 75 consecutive days following the summer solstice.

GEOGRAPHIC SETTING: The Primus soils are on debris aprons, valley walls, and fan terraces at elevations of 700 to 1600 meters. Slopes are 5 to 40 percent. These soils formed in mixed volcanic ash and reworked glacial drift. The climate consists of cool, dry summers and cold, wet winters. Mean annual precipitation ranges from 800 to 1,600 millimeters, and mean annual air temperature ranges from 2 to 6 degrees C. Frost free season is 40 to 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: This is the Stehekin series. Stehekin soils do not have andic soil properties and are located on unstable portions of valley walls and on debris cones adjacent to debris aprons.

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

USE AND VEGETATION: Used for watershed, recreation, woodland, and wildlife habitat. Potential natural vegetation consists of Douglas-fir, subalpine fir, and Engelmann spruce with an understory of pachistima, queen's cup bead lily, western rattlesnake plantain, dwarf bramble, starry false Solomon's seal, western meadow-rue and big huckleberry.

DISTRIBUTION AND EXTENT: Eastern slopes of the North Cascade Mountains, Washington. MLRA 3. Series is of moderate extent.

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

SERIES ESTABLISHED: North Cascades National Park Service Complex soil survey, 2011.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 3 to 103 centimeters (Bw1, Bw2, 2BC, and upper 19 centimeters of the 2C horizon)
Ochric epipedon: 0 to 18 centimeters (Oi, Oe, and upper 15 centimeters of Bw1 horizon)
Cambic horizon: 3 to 60 centimeters (Bw1 and Bw2 horizons)
Andic soil properties: 3 to 60 centimeters (Bw1 and Bw2 horizons)
Lithologic discontinuity: 60 centimeters
The 2BC horizon has ashy textural modifiers but does not meet the criteria for andic soil properties.

National Cooperative Soil Survey
U.S.A.