LOCATION IMNAK AK

Established Series
AJC/CBB
11/2024

IMNAK SERIES

Depth class: moderately deep to bedrock, paralithic
Drainage class: well drained
Parent material: gravelly loamy colluvium over gravelly residuum weathered from calcareous sandstone
Landscape: mountains
Landform: mountain slopes
Slopes: 10 to 35 percent
Mean annual precipitation: about 450 mm (17.72 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 85 days

TAXONOMIC CLASS: Fragmental, mixed Typic Haplocryolls

TYPICAL PEDON: Imnak extremely channery highly organic loam in a dryas and lichen tundra community on a west facing linear, convex backslope on a slope of 29 percent at an elevation of 477 m (1,565 ft)

Oa--0 to 7 cm (0 to 3 in); highly decomposed plant material, black (10YR 2/1) broken face moist, dark gray (10YR 4/1) broken face dry; many very fine, common fine, and few medium roots throughout; 12 percent channers; 25 % of SOC; 43.3 % of SOM; slightly acid (pH 6.3); clear wavy boundary. (2 to 14 cm, 1 to 6 in thick)

A1--7 to 14 cm (3 to 6 in); extremely channery highly organic loam, very dark brown (10YR 2/2) broken face moist, dark grayish brown (10YR 4/2) broken face dry; moderate fine granular structure; very friable, soft, nonsticky, nonplastic; nonsmeary; common very fine and fine roots throughout; very fine irregular pores; 1 percent prominent pinkish gray (7.5YR 7/2) carbonate coats on bottom of rock fragments; 5 percent flagstones, 65 percent channers; 10.5 % of SOC; 18 % of SOM; noneffervescent in the matrix, strongly effervescent on bottom of rock fragments; slightly acid (pH 6.5); abrupt smooth boundary. (5 to 10 cm, 2 to 4 in thick)

A2--14 to 34 cm (6 to 13 in); extremely channery fine sandy loam, very dark grayish brown (2.5Y 3/2) broken face moist, grayish brown (2.5Y 5/2) broken face dry; moderate fine granular structure; very friable, soft, nonsticky, nonplastic; nonsmeary; few fine roots throughout; very fine dendritic tubular and irregular pores; 5 percent prominent pinkish gray (7.5YR 7/2) carbonate coats on bottom of rock fragments; 5 percent flagstones, 65 percent channers; 5.75 % of SOC; 9.9 % of SOM; noneffervescent in the matrix, strongly effervescent on bottom of rock fragments; slightly alkaline (pH 7.5); clear irregular boundary. (15 to 25 cm, 6 to 10 in thick)

2C--34 to 52 cm (13 to 21 in); channers; few very fine and fine roots throughout; very coarse interstitial pores; 95 percent channers; clear irregular boundary. (15 to 46 cm, 6 to 18 in thick)

2Cr--52 to 77 cm (21 to 30 in); extremely weakly to moderately cemented calcareous sandstone bedrock. (25 cm, 10 in thick)

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64 degrees 54 minutes 59.77 seconds north, longitude 160 degrees 14 minutes 37.94 seconds west, datum WGS84, UTM north 7199738.55 and UTM east 441163.34, 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: 2 to 14 cm (1 to 6 in)
Thickness of mollic epipedon: 20 to 35 cm (8 to 14 in)
Depth to lithologic discontinuity: 22 to 49 cm (9 to 19 in)
Depth to paralithic contact: 50 to 100 cm (20 to 40 in)

Oa horizon:
Hue: 10YR or 7.5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: highly decomposed plant material
Rock fragments: 0 to 14 percent
Channers: 0 to 14 percent
Organic matter: 60 to 90 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)

A1 horizon:
Hue: 10YR or 7.5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: extremely or very channery highly organic loam or silt loam
Sand: 10 to 52 percent
Silt: 38 to 80 percent
Clay: 5 to 12 percent
Rock fragments: 50 to 80 percent
Channers: 50 to 70 percent
Flagstones: 0 to 30 percent
Organic matter: 10 to 19 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)

A2 horizon:
Hue: 2.5Y, 10YR, or 7.5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: extremely or very channery fine sandy loam or silt loam
Sand: 25 to 75 percent
Silt: 13 to 70 percent
Clay: 5 to 12 percent
Rock fragments: 40 to 75 percent
Channers: 40 to 75 percent
Flagstones: 0 to 20 percent
Organic matter: 2 to 8 percent
Reaction class: slightly acid to slightly alkaline (pH 6.1 to 7.8)

2C horizon:
Texture: channers
Rock fragments: 90 to 100 percent
Channers: 90 to 100 percent

2Cr horizon

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 300 to 580 meters (980 to 1,900 feet)
Parent material: gravelly loamy colluvium over gravelly residuum weathered from calcareous sandstone
Landform: mountain slopes
Slopes: 10 to 35 percent
Mean annual precipitation: 400 to 500 mm (16 to 20 in)
Mean annual air temperature: -6 to -2 degrees C. (21 to 28 degrees F.)
Frost free period: 70 to 85 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Tui, Iyagak, Kikku, Aklak, and Niakuk soils.
Tui soils have an ochric epipedon, a loamy-skeletal particle size class, and occur on similar landforms on backslope positions.
Iyagak soils have an ochric epipedon and occur on similar landforms on swales.
Kikku soils have a histic epipedon, aquic conditions at the soil surface, and occur on similar landforms on backslope positions.
Aklak soils is deep to lithic contact (100 to 150 cm, 40 to 60 in) and occurs on similar landforms on backslope positions.
Niakuk soils have an ochric epipedon, ultra acid to strongly acid reaction classes throughout the profile, and occur on similar landforms on backslope positions.

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

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: eightpetal mountain-avens, gregreen reindeer lichen, black crowberry, alpine azalea, star reindeer lichen, snow lichen, globe ball lichen, white arctic mountain heather, alpine sweetgrass, reindeer lichen, Flavocetraria culcullata, northern singlespike sedge, Flavocetraria nivalis, dwarf birch, bog blueberry, Richardson's brookfoam, Altai fescue, arctic lupine, and golden asahinea lichen.

DISTRIBUTION AND EXTENT: MLRA 240, Nulato Hills-Southern Seward Peninsula Highlands. The series is of moderate 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: 32 to 52 cm (13 to 20 in)

Mollic epipedon: 7 to 34 cm (3 to 13 in) (A horizons)

Lithologic discontinuity: 34 to 77 cm (13 to 30 in) (2C and 2Cr horizons)

Paralithic contact: 52 cm (20 in) (2Cr horizon)

ADDITIONAL DATA:

User pedon ID: 2023AK180428

National Cooperative Soil Survey
U.S.A.