LOCATION WILLOW RIVER            AK

Established Series
MJS/CBB
11/2024

WILLOW RIVER SERIES

Depth class: very deep
Drainage class: well drained
Parent material: sandy and gravelly alluvium derived from metamorphic and sedimentary rock
Landscape: river valleys
Landform: flood plains
Slopes: 0 to 5 percent
Mean annual precipitation: about 400 mm (16 in)
Mean annual air temperature: about -3 degrees C. (27 degrees F.)
Frost-free period: 75 to 90 days

TAXONOMIC CLASS: Sandy-skeletal, mixed Typic Cryofluvents

TYPICAL PEDON: Willow River extremely gravelly sandy loam in a feltleaf willow and balsam poplar community on an east facing linear, linear floodplain on a slope of 2 percent at an elevation of 136 m (446 ft)

Oi--0 to 2 cm (0 to 1 in); extremely gravelly slightly decomposed plant material, very dark brown (7.5YR 2.5/2) moist, brown (7.5YR 4/2) dry; many very fine and fine roots throughout; 70 percent gravel; slightly acid (pH 6.3); clear wavy boundary. (0 to 3 cm, 0 to 1 in thick)

A--2 to 5 cm (1 to 2 in); extremely gravelly sandy loam, very dark gray (7.5YR 3/1) moist, gray (7.5YR 5/1) dry; moderate medium subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; many very fine and fine and few medium roots throughout; very fine irregular pores; 70 percent gravel; neutral (pH 7.1); clear wavy boundary. (0 to 5 cm, 0 to 2 in thick)

C--5 to 50 cm (2 to 20 in); extremely gravelly sand, dark gray (2.5Y 4/1) moist, gray (2.5Y 6/1) dry; single grain; loose, nonsticky, nonplastic; nonsmeary; many fine, common very fine and coarse, and few medium roots throughout; very fine irregular pores; 65 percent gravel; neutral (pH 7.2); clear smooth boundary. (25 to 70 cm, 10 to 28 in thick)

Bwb--50 to 64 cm (20 to 25 in); sandy loam, very dark grayish brown (10YR 3/2) moist, grayish brown (10YR 5/2) dry; weak medium subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; few medium roots throughout; very fine irregular pores; 10 percent gravel; slightly alkaline (pH 7.5); clear smooth boundary. (3 to 15 cm, 1 to 6 in thick)

C' --64 to 200 cm (25 to 79 in); extremely gravelly sand, dark gray (2.5Y 4/1) moist, gray (2.5Y 6/1) dry; single grain; loose, loose, nonsticky, nonplastic; nonsmeary; few medium roots top of horizon; very fine interstitial and irregular pores; 65 percent gravel; slightly alkaline (pH 7.5). (107 to 172 cm, 42 to 68 in thick)

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64 degrees 16 minutes 4.88 seconds north, longitude 160 degrees 6 minutes 43.06 seconds west, datum WGS84, UTM north 7127352.02 and UTM east 446135.30, zone 4W, datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: 0 to 3 degrees C. (32 to 37 degrees F.)
Thickness of organic material: 0 to 3 cm (0 to 1 in)
Thickness of ochric epipedon: 1 to 8 cm (0.5 to 3 in)

Oi horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 3
Texture: extremely or very gravelly slightly decomposed plant material
Rock fragments: 35 to 80 percent
Organic matter: 60 to 90 percent
Reaction class: moderately acid to slightly acid (pH 5.6 to 6.5)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: extremely or very gravelly sandy loam
Sand: 43 to 82 percent
Silt: 11 to 50 percent
Clay: 3 to 12 percent
Rock fragments: 50 to 80 percent
Organic matter: 2 to 8 percent
Reaction class: moderately acid to slightly alkaline (pH 5.6 to 7.8)

C horizons:
Hue: 2.5Y or 5Y
Value: 2 to 4 moist, 4 to 6 dry
Chroma: 1 to 2
Texture: extremely or very gravelly sand or coarse sand
Sand: 85 to 100 percent
Silt: 0 to 12.9 percent
Clay: 0.1 to 5 percent
Rock fragments: 50 to 80 percent
Organic matter: 0.1 to 2.5 percent
Reaction class: slightly acid to slightly alkaline (pH 6.1 to 7.8)

Bwb horizon:
Hue: 10YR, 2.5Y, or 5Y
Value: 3 to 4 moist, 5 to 6 dry
Chroma: 2 to 3
Texture: sandy loam, very fine sandy loam, or their gravelly analogues
Sand: 43 to 78 percent
Silt: 14 to 49 percent
Clay: 2 to 8 percent
Rock fragments: 0 to 25 percent
Organic matter: 1 to 4 percent
Reaction class: slightly acid to slightly alkaline (pH 6.1 to 7.8)

COMPETING SERIES: These are the Chenega, Hollow, Kidazqeni, Malmesbury, Stratify, Togiak, and Shovelcreek (AK) series.
Chenega soils have a mean annual precipitation of 1150 to 2550 mm (45 to 100 in), are somewhat excessively drained, and occur on flood plains, stream terraces, and alluvial fans.
Hollow soils are calcareous in the control section, are somewhat poorly drained and frequently flooded, and occur on flood plains and outwash plains.
Kidazqeni soils have a thin mantle of stratified loamy and sandy alluvium at depths between 2 to 8 cm (1 to 3 in), are moderately well or well drained, and occur on flood plains, stream terraces, and alluvial fans.
Malmesbury soils have buried O horizons, a mean annual air temperature of 7 degrees C. (45 degrees F.), and occur on flood plains and stream terraces.
Stratify soils have very gravelly sand stratified with thin lenses of silt loam and fine sandy loam in the substratum, substantial mica content in the profile, are moderately well drained, and occur on flood plains and low terraces.
Togiak soils have a mean annual precipitation of about 760 mm (30 in), are somewhat excessively drained, and occur on beach berms of shore complexes.
Shovelcreek soils do not have buried horizons and occur on rarely flooded flood plains.

GEOGRAPHIC SETTING:
Elevation: 0 to 250 meters (0 to 820 feet)
Parent material: sandy and gravelly alluvium derived from metamorphic and sedimentary rock
Landform: flood plains
Slopes: 0 to 5 percent
Mean annual precipitation: 300 to 500 mm (12 to 20 in)
Mean annual air temperature: -5 to -1 degrees C. (23 to 30 degrees F.)
Frost free period: 75 to 90 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Uliktuk, Alliksuk, and Kiuriruk soils.
Uliktuk soils have a reduced matrix and aquic conditions at depths below 8 to 15 cm (3 to 6 in) and occur on frequently flooded floodplains.
Alliksuk soils have a cambic horizon that is 40 to 125 cm (16 to 49 in) thick and occur on terraces of river valleys.
Kiuriruk soils have a histic epipedon, permafrost at depths between 50 to 100 cm (20 to 40 in), and occur on terraces of river valleys.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in the Oi and C horizons, high in the A horizon, and moderately high to high in the Bwb horizon
Permeability: rapid to very rapid in the Oi horizon, moderate to rapid in the A and Bwb horizons, and very rapid in the C horizons
Flooding: occasional/brief
Ponding: none
Runoff: very low

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: feltleaf willow, balsam poplar, fescue, moss, splendid feather moss, alpine sweetvetch, bedstraw, white spruce, siberian alder, and mountain deathcamas.

DISTRIBUTION AND EXTENT: MLRA 240, Nulato Hills-Southern Seward Peninsula Highlands. The series is of small extent.

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

SERIES ESTABLISHED: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey, Alaska, 2024.

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

Particle-size control section: 27 to 102 cm (11 to 40 in)

Ochric epipedon: 0 to 5 cm (0 to 2 in) (Oi and A horizons)

ADDITIONAL DATA:

User pedon ID: 2021AK180798

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National Cooperative Soil Survey
U.S.A.