LOCATION ATNATUU                 AK

Established Series
SDB/MJS
08/2025

ATNATUU SERIES

Depth class: very deep
Drainage class: poorly drained
Parent material: Organic material over colluvium and/or till
Landscape: mountains
Landform: mountain slopes
Slopes: 1 to 25 percent
Mean annual precipitation: about 350 mm (14 in)
Mean annual air temperature: about 0.5 degrees C. (33 degrees F)
Frost-free period: 89 to 103 days

TAXONOMIC CLASS: Loamy, mixed, euic Terric Cryosaprists

TYPICAL PEDON: Atnatuu muck on an alder mountain slope at 262 m (860 ft)

Oi--0 to 10 cm (0 to 4 in); slightly decomposed plant material, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; common very fine and medium roots throughout; neutral (pH 7.3); abrupt wavy boundary (5 to 15 cm, 2 to 6 in)

Oa--10 to 70 cm (4 to 28 in); muck, black (10YR 2/1) moist; many very fine, common fine, medium, and coarse roots throughout; 5 percent angular cobbles by volume; noneffervescent; moderately alkaline (pH 8.0). (50 to 75 cm, 20 to 30 in)

C--70 to 200 cm (28 to 79 in); silt loam, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, nonsticky, nonplastic; nonsmeary; very fine irregular pores; 10 percent angular cobbles by volume; moderately alkaline (pH 8.0). (110 to 145 cm, 43 to 57 in)

TYPE LOCATION: North Copper River Soil Survey Area, Alaska; latitude 61.558542, longitude -144.452727, UTM 6827648.53 North and 635321.34 East, zone 6, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: aquic
Soil temperature regime: cryic
Mean annual soil temperature: 1 to 5 degrees C. (34 to 41 degrees F)
Thickness of organic material: 55 to 90 cm (22 to 35 in)
Depth to aquic conditions: 5 to 15 cm (2 to 6 in)

Oi, Oe and Oa horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 3
Texture: Slightly decomposed organic material, mucky peat, or muck
Organic matter: 60 to 90 percent
Reaction class: neutral to moderately alkaline (pH 6.6 to 8.4)

C horizon:
Hue: 2.5Y or 5Y
Value: 4 to 5
Chroma: 2 to 5
Texture: Silt loam
Sand: 10 to 48 percent
Silt: 50 to 80 percent
Clay: 2 to 12 percent
Rock fragments: 0 to 14 percent
Cobbles: 0 to 14 percent
Organic matter: 0.5 to 2 percent
Reaction class: neutral to moderately alkaline (pH 6.6 to 8.4)

COMPETING SERIES: This is the Nonvalnuk (AK) soil.
Nonvalnuk soils do not have a slightly decomposed organic matter surface horizon and are very poorly drained.

GEOGRAPHIC SETTING:
Elevation: 200 to 800 meters (655 to 2625 ft)
Parent material: organic material over colluvium and/or till
Landform: mountain slopes
Slopes: 1 to 25 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 Rocklake, Secondlake, and Taral soils.
Rocklake soils are less than 50cm deep to bedrock and occur on escarpments and mountain slopes.
Secondlake soils are well drained, have a mollic epipedon and occur on mountain slopes.
Taral soils have a deep (>40 cm, 16 in thick) mollic epipedon and occur on mountain slopes with a slope greater than 25 percent.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: poorly drained
Saturated Hydraulic Conductivity: very high in the Oi horizon, high in the Oa horizon, moderately high in the C horizon
Permeability: very rapid in the Oi horizon, moderate in the Oa and C horizons
Runoff: very high

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: Alter, meadow horsetail

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: 70 to 100 cm (28 to 39 in)

Fibric soil material 0 to 10 cm (0 to 4 in) (Oi horizon)

Sapric soil material: 10 to 70 cm (4 to 28 in) (Oa horizon)

Aquic conditions: 10 to 70 cm (4 to 28 in) (Oa horizon)

User pedon Id: 2022AK261321

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National Cooperative Soil Survey
U.S.A.