LOCATION KENNECOTT               AK

Established Series
SDB
08/2025

KENNECOTT SERIES

Depth class: very deep
Drainage class: well drained
Parent material: silty noncalcareous loess over sandy and gravelly alluvium
Landscape: mountains
Landform: river valleys, terraces
Slopes: 6 to 12 percent
Mean annual precipitation: about 350 mm (14 in)
Mean annual air temperature: about -0.5 degrees C. (31 degrees F)
Frost-free period: 89 to 103 days

TAXONOMIC CLASS: Coarse-loamy over sandy or sandy-skeletal, mixed, superactive Cumulic Haplocryolls

TYPICAL PEDON: Kennecott silt loam in a willow mixed shrub community on a linear, linear terrace tread on a slope of 11 percent at an elevation of 187m (615 ft).

Oe--0 to 8 cm (0 to 3 in); moderately decomposed plant material, dark brown (7.5YR 3/4) moist; common very fine, fine, medium, coarse, and very coarse roots throughout; noneffervescent; slightly alkaline (pH 7.4); clear smooth boundary (6 to 10 cm, 2 to 4 in)

A--8 to 17 cm (3 to 7 in); silt loam, black (7.5YR 2.5/1) moist; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; nonsmeary; common very fine, fine, many medium, common coarse, and very coarse roots throughout; very fine and fine dendritic tubular pores; neutral (pH 6.9); clear smooth boundary (6 to 12 cm, 2 to 5 in)

Bw--17 to 84 cm (7 to 33 in); silt loam, 85 percent very dark brown (10YR 2/2) and 15 percent dark brown (7.5YR 3/4) moist; weak thick platy structure; soft, very friable, nonsticky, nonplastic; nonsmeary; common very fine and fine, many medium, and common coarse roots throughout; very fine and fine dendritic tubular pores; very slight effervescence; neutral (pH 7.2); abrupt smooth boundary (40 to 75 cm, 16 to 30 in)

2C--84 to 150 cm (33 to 59 in); extremely gravelly coarse sand, very dark grayish brown (2.5Y 3/2) moist; single grain; loose, loose, nonsticky, nonplastic; nonsmeary; carbonate, finely disseminated; 5 percent cobbles by volume, 60 percent gravel by volume; very slight effervescence; slightly alkaline (pH 7.4) (63 to 104 cm, 25 to 41 in)

TYPE LOCATION: North Copper River Soil Survey Area, Alaska; latitude 61.58028, longitude -144.4338, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: -2 to 1 degrees C. (28 to 34 degrees F)
Thickness of organic material: 6 to 10 cm (2 to 4 in)
Thickness of mollic epipedon: 40 to 77 cm (16 to 30 in)
Depth to lithologic discontinuity: 46 to 87 cm (18 to 34 in)

Oe horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 2
Texture: moderately decomposed organic material
Organic matter: 60 to 90 percent
Reaction class: neutral to slightly alkaline (pH 6.6 to 7.8)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 2
Texture: silt loam
Sand: 20 to 43 percent
Silt: 50 to 70 percent
Clay: 2 to 12 percent
Rock fragments: 0 percent
Organic matter: 6 to 8 percent
Reaction class: neutral to slightly alkaline (pH 6.6 to 7.8)

Bw horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 2 to 3
Texture: silt loam
Sand: 20 to 43 percent
Silt: 50 to 70 percent
Clay: 2 to 12 percent
Rock fragments: 0 percent
Organic matter: 6 to 8 percent
Reaction class: neutral to slightly alkaline (pH 6.6 to 7.8)

2C horizon:
Hue: 10YR or 2.5Y
Value: 3 to 4
Chroma: 2 to 4
Texture: very gravelly coarse sand, extremely gravelly coarse sand
Sand: 90 to 99 percent
Silt: 0 to 9 percent
Clay: 1 to 5 percent
Rock fragments: 52 to 72 percent
Gravels: 50 to 65 percent
Cobbles: 2 to 7 percent
Organic matter: 0.75 to 2.5 percent
Reaction class: neutral to slightly alkaline (pH 6.6 to 7.8)

COMPETING SERIES: These are no competing series.

GEOGRAPHIC SETTING:
Elevation: 100 to 700 meters (330 to 2295 ft)
Parent material: silty noncalcareous loess over sandy and gravelly alluvium
Landform: river valleys, terraces
Slopes: 6 to 12 percent
Mean annual precipitation: 300 to 500 mm (12 to 20 in)
Mean annual air temperature: -2 to 1 degrees C. (28 to 34 degrees F)
Frost-free period: 89 to 103 days

GEOGRAPHICALLY ASSOCIATED SOILS: these are the Centuu, Ellisgap, Fishwheel, and Ride series.
Centuu soils are well drained, have an mollic epipedon, and occur on river valleys and alluvial fans.
Ellisgap soils are a poorly drained, have permafrost, have histic epipedons, have cryoturbation starting begins between 14 and 27 cm (6 to 11 in) deep, and occur in river valleys and terraces.
Fishwheel soils are moderately well drained, have a mollic epipedon, and occur on terraces and glacial valley floors.
Ride soils are somewhat excessively drained, and occur on mountain slopes and hillslopes.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in the Oe and 2C, and moderately high in the A and Bw horizons
Permeability: very rapid in the Oe and 2C, and moderate in the A and Bw horizons
Runoff: medium

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: squashberry, resin birch, scouler's willow

DISTRIBUTION AND EXTENT: MLRA 228, Interior Alaska mountains.
Extent: limited

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Wasilla, Alaska

SERIES ESTABLISHED: North Copper River Soil Survey, Alaska, 2024.

REMARKS: Diagnostic features and horizons recognized in this profile include:

Particle-size control section: 33 to 108 cm (13 to 43 in)

Mollic epipedon: 8 to 84 cm (3 to 33 in) (A and Bw horizons)

Lithologic discontinuity: 84 to 150 cm (33 to 59 in) (2C horizon)

ADDITIONAL DATA:

User pedon Id: 2018AK261006

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National Cooperative Soil Survey
U.S.A.