LOCATION ALTERATIONCREEK         AK

Established Series
SDB/MJS
08/2025

ALTERATIONCREEK SERIES

Depth class: deep to bedrock, lithic
Drainage class: well drained
Parent material: silty loess over gravelly colluvium
Landscape: mountains and foothills
Landform: mountain valleys and hillslopes
Slopes: 10 to 40 percent
Mean annual precipitation: about 410 mm (16 in)
Mean annual air temperature: about -2 degrees C. (28 degrees F)
Frost-free period: 32 to 103 days

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Typic Humicryepts

TYPICAL PEDON: Alterationcreek silt loam in a white spruce woodland dominated by willow and alder on a south facing linear, linear backslope on a slope of 14 percent at an elevation of 1032m (3385 ft)

Oa--0 to 10 cm (0 to 4 in); highly decomposed plant material, dark gray (10YR 4/1) dry, black (10YR 2/1) broken face moist; many very fine and fine, and few medium roots throughout; strongly acid (pH 5.4); clear wavy boundary. (8 to 14 cm, 3 to 6 in)

A--10 to 16 cm (4 to 6 in); silt loam, 80 percent very dark grayish brown (10YR 3/2) broken face and 20 percent black (10YR 2/1) broken face moist; weak fine subangular blocky structure; soft, very friable, moderately sticky, moderately plastic; nonsmeary; many very fine and fine roots throughout; very fine and fine dendritic tubular pores; moderately acid (pH 5.8); abrupt wavy boundary. (5 to 30 cm, 2 to 12 in)

Bw--16 to 35 cm (6 to 14 in); silt loam, very dark grayish brown (2.5Y 3/2) broken face moist; weak medium subangular blocky structure; soft, very friable, moderately sticky, moderately plastic; nonsmeary; few very fine and fine roots throughout; few very fine dendritic tubular pores; 7 percent angular channers by volume; moderately acid (pH 5.8); clear wavy boundary. (18 to 30 cm, 7 to 12 in)

C--35 to 110 cm (14 to 43 in); extremely flaggy silt loam, very dark grayish brown (2.5Y 3/2) broken face moist; massive; soft, very friable, slightly sticky, nonplastic; nonsmeary; few very fine roots throughout; very fine dendritic tubular and interstitial pores; 30 percent angular channers by volume, 45 percent angular flagstones by volume; moderately acid (pH 5.9). (70 to 80 cm, 28 to 31 in)

2R--110 to 135 cm (43 to 53 in); Bedrock.

TYPE LOCATION: North Copper River Soil Survey Area, Alaska; latitude 62.921164, longitude -143.206433, UTM 6978726.86 north, and 387953.47 east, zone 7, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: 0 to 5 degrees C. (32 to 41 degrees F)
Thickness of organic material: 8 to 14 cm (3 to 6 in)
Thickness of epipedon: 23 to 60 cm (9 to 24 in)
Depth to lithic contact: 101 to 154 cm (40 to 61 in)

Oe and Oa horizons:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 3
Texture: slightly decomposed organic material to highly decomposed organic material
Organic matter: 60 to 90 percent
Reaction class: extremely acid to moderately acid (pH 3.5 to 6.0)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 4
Chroma: 1 to 3
Texture: Silt loam, sandy loam
Sand: 10 to 60 percent
Silt: 28 to 80 percent
Clay: 5 to 12 percent
Organic matter: 2 to 6 percent
Reaction class: very strongly acid to moderately acid (pH 4.5 to 6)

Bw horizon:
Hue: 10YR or 2.5Y
Value: 3 to 4
Chroma: 1 to 3
Texture: silt loam, channery silt loam, loam, channery silt loam
Sand: 20 to 52 percent
Silt: 33 to 74 percent
Clay: 6 to 15 percent
Rock fragments: 5 to 34 percent channers
Organic matter: 1 to 3 percent
Reaction class: strongly acid to slightly acid (pH 5.1 to 6.5)

C horizon:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 2 to 4
Texture: very flaggy silt loam, extremely flaggy silt loam, very flaggy sandy loam, extremely flaggy sandy loam.
Sand: 20 to 65 percent
Silt: 23 to 75 percent
Clay: 5 to 12 percent
Rock fragments: 40 to 90 percent
Channers: 15 to 34 percent
Flagstones: 25 to 54 percent
Organic matter: 0.4 to 2 percent
Reaction class: strongly acid to slightly acid (pH 5.1 to 6.0)

2R Horizon:
Indurated bedrock

Some pedons have a sandy-skeletal substratum at depths greater than 127 cm (50 in).

COMPETING SERIES: These are the Atayak(AK), Bergbay(AK), Buell(UT), Ibach(AK), Mccall(ID), Moran(WY), Springcamp(AK), Suslota(AK), Tolstoipoint(AK), and Walcott(WY) soils.
Atayak soils lack a loess cap and occurs on escarpments in plains
Berbay soils lack a loess cap and is moderately deep.
Buell, Mccall, and Moran soils have a mean annual soil temperature greater than 1 C (34 degrees F).
Ibach soils lack a lithic contact and has diorite cobbles and stones in all horizons.
Springcamp soils have a paralithic contact.
Suslota, Tolstoipoint, and Walcott soils lack a lithic contact, and lack a loess cap

GEOGRAPHIC SETTING:
Elevation: 800 to 1200 meters (2625 to 3935 ft)
Parent material: silty loess over gravelly colluvium
Landform: mountain valleys and hillslopes
Slopes: 10 to 40 percent
Mean annual precipitation: 350 to 800 mm (14 to 31 in)
Mean annual air temperature: -3.5 to 1 degrees C. (26 to 34 degrees F)
Frost free period: 32 to 103 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chelina, Drashner, Haggardcreek, Hundell, and Fourthofjuly soils.
Chelina soils lack an umbric epipedon, have fine loamy lacustrine parent materials, and occur on the ancient shorelines of lake plains.
Drashner soils have a histic epipedon, a cambic horizon, and occur on till covered hillslopes.
Fourthofjuly soils have a cambic horizon and occur on mountain valleys and stream terraces
Haggardcreek soils lack an umbric epipedon and occur on hills and mountain slopes.
Hundell soils have sandy outwash as parent material and occur on flats and bluffs.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in O horizon, moderately high in A, Bw, and C horizon, very low to moderately low in R horizon
Permeability: very rapid in O horizon, moderately in A, Bw, and C horizon, very slow to moderately slow in R horizon
Runoff: medium

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: White spruce, alder, Robinson's willow, feltleaf willow, and diamondleaf willow.

DISTRIBUTION AND EXTENT: MLRA 228 Interior Alaska mountains
Extent: Extensive

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: 35 to 110 cm (14 to 43 in)

Umbric epipedon: 10 to 35 cm (4 to 14 in) (A and Bw horizons)

Lithic contact: 101 to 154 cm (40 to 61 in) (R horizon)

Lithologic discontinuity: 101 to 154 cm (40 to 61 in) (R horizon)

ADDITIONAL DATA:

User pedon Id: 2023AK261250

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National Cooperative Soil Survey
U.S.A.