LOCATION PERFECT                 WA

Established Series
Rev. CAB/SBC
06/2011

PERFECT SERIES

The Perfect series consists of very deep, well drained soils formed in minor amounts of volcanic ash mixed with reworked glacial drift and colluvium on valley walls and debris cones. Slopes are 15 to 75 percent. The mean annual precipitation is about 1750 millimeters. The mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Sandy-skeletal, isotic Vitrandic Dystrocryepts

TYPICAL PEDON: Perfect ashy sandy loam, on a valley wall landform with a SE facing slope of 75 percent at 825 meters elevation under coniferous forest vegetation. When described on July 30, 2008 the soil was moist throughout. (Colors are for moist soil unless otherwise noted.)

Oi--0 to 3 cm; slightly decomposed plant material; abrupt wavy boundary.

Oe--3 to 4 cm; moderately decomposed plant material; many very fine roots and common fine, medium, and coarse roots throughout; abrupt irregular boundary.

Bw--4 to 7 cm; dark yellowish brown (10YR 3/4) ashy sandy loam, yellowish brown (10YR 5/4) dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine, many fine and medium, and few coarse and very coarse roots throughout; 5 percent fine gravel and 5 percent medium and coarse gravel; moderately acid (pH 5.7); abrupt irregular boundary.

Oeb--7 to 11 cm; moderately decomposed plant material; common very fine, fine, and medium roots and few coarse roots throughout; abrupt irregular boundary.

Eb--11 to 13 cm; dark gray (10YR 4/1) ashy sandy loam, gray (10YR 5/1) dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine and fine and few medium and coarse roots throughout; 5 percent fine gravel and 5 percent medium and coarse gravel; strongly acid (pH 5.4); abrupt irregular boundary.

Bwb--13 to 39 cm; dark yellowish brown (10YR 3/4) ashy gravelly sandy loam, dark yellowish brown (10YR 4/4) dry; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; few very fine, fine, medium, coarse and very coarse roots throughout; 5 percent fine gravel, 5 percent medium and coarse gravel, and 5 percent cobbles; moderately acid (pH 5.7); clear wavy boundary.

2BCb1--39 to 73 cm; olive brown (2.5Y 4/4) extremely cobbly loamy sand, light olive brown (2.5Y 5/4) dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; 20 percent fine gravel, 20 percent medium and coarse gravel, 25 percent cobbles, and 5 percent stones; slightly acid (pH 6.1); abrupt smooth boundary.

2BCb2--73 to 150 cm; olive brown (2.5Y 4/3) extremely gravelly loamy sand, light olive brown (2.5Y 5/3) dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; 20 percent fine gravel, 20 percent medium and coarse gravel, and 25 percent cobbles; slightly acid (pH 6.3).

TYPE LOCATION: North Cascades National Park, Whatcom County, Washington; 88 meters west and 115 meters south of NE corner of Section 20, T37N, R14E Willamette Meridian; Crater Mountain, Washington USGS quadrangle; 48 degrees, 40 minutes, 59.4 seconds north latitude, 120 degrees, 59 minutes, 57 seconds west longitude; NAD83; UTM 647265 meters E, 5394168 meters N, zone 10.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 4 to 8 degrees C. Cryic soil temperature regime.
Soil moisture control section: dry for less than 30 consecutive days from June to October. Udic soil moisture regime.

Bw and Bwb horizons:
Hue -10YR
Value - 3 to 4 moist, 4 to 6 dry
Chroma - 2 to 4 moist or dry
Fine earth texture - ashy LS, ashy SL, or ashy COSL
Rock fragments - 0 to 65 percent total
0 to 45 percent gravel
0 to 20 percent cobbles
0 to 10 percent stones
Clay content - 1 to 8 percent
Volcanic glass - 0 to 5 percent
Reaction - strongly acid to slightly acid
Thickness - 50 to 80 centimeters

E or Eb horizons are sometimes present. Thickness ranges from 2 to 5 cm, textures of ashy SL, ashy FSL, or LS, reaction of very strongly to moderately acid, hues of 10YR with values of 4 to 6 moist and chromas of 1 to 3 moist.

2BC and 2BCb horizons:
Hue - 2.5Y or 10YR
Value - 3 to 4 moist, 5 to 6 dry
Chroma - 2 to 4 moist or dry
Fine earth texture - LS, LCOS or LFS
Rock fragments - 35 to 85 percent total
35 to 50 percent gravel
0 to 35 percent cobbles
0 to 10 percent stones
Clay content - 0 to 5 percent
Volcanic glass - 0 to 5 percent
Reaction - moderately acid to slightly acid

COMPETING SERIES: There are no competing series in this or similar families.

GEOGRAPHIC SETTING: The Perfect soils are on valley walls and debris cones at elevations of 750 to 1500 meters. Slopes are 15 to 75 percent. These soils formed in reworked glacial drift and colluvium with minor amounts of volcanic ash. The climate consists of cool, dry summers and cold, wet winters. Mean annual precipitation ranges from 1800 to 3300 millimeters, and mean annual air temperature ranges from 2 to 6 degrees C. Frost free season is 30 to 60 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Forbidden (T), Harlequin (T), Tepeh (T) and Triumph (T) series. Forbidden and Tepeh soils have andic soil properties and are found on more stable portions of the same landforms. Harlequin soils have a lithic contact at less than 50 centimeters, and are found in association with Perfect soils on steep portions of valley walls. Triumph soils are found under the herbaceous portions of the same debris cones.

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 primarily of Pacific silver fir, mountain hemlock, and western red cedar with an understory of vine maple, pachistima, red huckleberry, Alaska huckleberry, queen's cup bead lily, and rattlesnake plantain.

DISTRIBUTION AND EXTENT: Western 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:
Ochric epipedon: 0 to 18 centimeters (Oi, Oe, Bw1, Oeb, Eb, and upper 5 cm of Bwb) horizons)
Cambic horizon: 4 to 7 and 13 to 39 centimeters (Bw and Bwb horizons)
Vitrandic feature: 4 to 7 and 11 to 39 centimeters (Bw, Eb, and Bwb horizons)
Particle-size control section: 29 to 104 centimeters (25 to 100 centimeters from the mineral surface)

---

National Cooperative Soil Survey
U.S.A.