LOCATION ATKAKTUK                AK

Tentative Series
SAS/MPS
10/2024

ATKAKTUK SERIES

Depth class: very deep
Drainage class: well drained
Parent material: gravelly loamy colluvium over gravelly colluvium derived from sandstone
Landscape: mountains
Landform: mountain slopes
Slopes: 15 to 75 percent
Mean annual precipitation: about 500 mm (19.7 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 90 days

TAXONOMIC CLASS: Loamy-skeletal over fragmental, isotic over mixed, acid, subgelic Typic Humigelepts

TYPICAL PEDON: Atkaktuk extremely cobbly highly organic silt loam in a dryas lichen talus slope alpine community on a northeast facing linear, linear backslope on a slope of 49 percent at an elevation of 535m (1755 ft)

A1--0 to 13 cm (0 to 5 in); extremely cobbly highly organic silt loam; black (10YR 2/1) moist, dark gray (10YR 4/1) dry; weak fine granular structure; very friable, soft, nonsticky, nonplastic; nonsmeary; many very fine and common fine roots throughout; common very fine and fine dendritic tubular pores; 5 percent stones, 15 percent gravel, 45 percent cobbles; noneffervescent; very strongly acid (pH 4.7); clear irregular boundary. (5 to 15 cm, 2 to 6 in thick)

A2--13 to 45 cm (5 to 18 in); extremely stony loam; very dark grayish brown (10YR 3/2) moist, grayish brown (10YR 5/2) dry; weak medium granular structure; very friable, soft, nonsticky, nonplastic; nonsmeary; common very fine and fine roots throughout; few very fine tubular pores; 5 percent gravel, 15 percent cobbles, 45 percent stones; noneffervescent; very strongly acid (pH 4.9); clear irregular boundary. (30 to 45 cm, 12 to 18 in thick)

2C--45 to 200 cm (18 to 79 in); cobbles; many very coarse interstitial and common coarse interstitial pores; 5 percent gravel, 15 percent stones, 80 percent cobbles.

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64.3798034, longitude -160.2193957, datum WGS84, UTM north 7139902.27 and UTM east 441170.37, zone 4, datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: gelic
Mean annual soil temperature: -1 to 0 degrees C. (30 to 32 degrees F.)
Thickness of umbric epipedon: 35 to 60 cm (14 to 24 in)

A1 horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 to 3
Texture: highly organic silt loam or its cobbly analogue
Sand: 5 to 45 percent
Silt: 50 to 83 percent
Clay: 3 to 15 percent
Rock fragments: 60 to 70 percent
Gravels: 0 to 30 percent
Cobbles: 20 to 55 percent
Stones: 0 to 10 percent
Organic matter: 10 to 19 percent
Reaction class: extremely acid to very strongly acid (pH 3.5 to 5.0)

A2 horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 to 4
Texture: silt loam, loam or their stony analogues
Sand: 15 to 50 percent
Silt: 35 to 80 percent
Clay: 3 to 15 percent
Rock fragments: 60 to 85 percent
Gravels: 0 to 10 percent
Cobbles: 0 to 25 percent
Stones: 25 to 90 percent
Organic matter: 2 to 8 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

2C horizon:
In lieu of texture: stones, cobbles
Rock fragments: 90 to 100 percent
Gravels: 0 to 10 percent
Cobbles: 35 to 90 percent
Stones: 5 to 50 percent

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 250 to 800 meters (820 to 2625 feet)
Parent material: gravelly loamy colluvium over gravelly colluvium derived from sandstone
Landform: mountain slopes
Slopes: 15 to 75 percent
Mean annual precipitation: 400 to 600 mm (16 to 24 in)
Mean annual air temperature: -6 to -1 degrees C. (21 to 30 degrees F.)
Frost free period: 70 to 90 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aklak, Aullasik, Continentaldivide, Ingik, Kulik, Managaarak, Nautchiak, Nunanjiak, Tatkik, and Ugguktuk soils.
Aklak soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), have a fragmental layer starting at depths between 22 to 78 cm (9 to 31 in), have a mollic epipedon, have a fragmental particle size class, and occur on mountainflanks, upper and center thirds
Aullasik soils have a lithic contact at depths between 150 to 200 cm (60 to 79 in), have a cambic horizon, lack a fragmental layer, have a loamy-skeletal particle size class, have a cryic soil temperature regime, and occur on mountainflanks, center third
Continentaldivide soils have a lithic contact at depths between 25 to 50 cm (10 to 20 in), have an mollic epipedon, lack a fragmental layer, have a loamy-skeletal particle size class, have a nonacid reaction class, and occur on ridges
Ingik soils have a paralithic contact at depths between 50 to 100 cm (20 to 40 in), have an ochric epipedon, lack a fragmental layer, have a loamy-skeletal particle size class, have a nonacid reaction class, have a cryic soil temperature regime, and occur on similar landforms on mountainflanks, upper third
Kulik soils have a lithic contact at depths between 50 to 100 cm (20 to 40 in), have an mollic epipedon, have a cambic horizon, lack a fragmental layer, have a loamy-skeletal particle size class, have a nonacid reaction class, and occur on mountainflanks, upper and center thirds
Managaarak soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), have a fragmental layer starting at depths between 41 to 93 cm (16 to 37 in), have an ochric epipedon, have a loamy-skeletal particle size class, and occur on similar landforms on mountainflanks, upper third
Nautchiak soils have an ochric epipedon, have a cambic horizon, lack a fragmental layer, have a loamy-skeletal particle size class, have a cryic soil temperature regime, and occur on drainageways or swales
Nunanjiak soils have a paralithic contact at depths between 100 to 150 cm (40 to 60 in), have a folistic epipedon, have a cambic horizon, lack a fragmental layer, have andic soil properties, can have spodic materials, have a medial over loamy-skeletal particle size class, have a cryic soil temperature regime, and occur on headslopes and mountainflanks, center third
Tatkik soils have aquic conditions starting between 25 to 50 cm (10 to 20 in), have a reduced matrix starting within 50 cm (20 in), have an ochric epipedon, have a cambic horizon, lack a fragmental layer, have a loamy-skeletal particle size class, have a nonacid reaction class, have a cryic soil temperature regime, and occur on swales
Ugguktuk soils have a lithic contact at depths between 50 to 100 cm (20 to 40 in), have aquic conditions starting between 25 to 50 cm (10 to 20 in), have a reduced matrix starting within 50 cm (20 in), have an ochric epipedon, have a cambic horizon, lack a fragmental layer, have a loamy-skeletal particle size class, have a cryic soil temperature regime, and occur on saddles and broad ridges

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: moderately high to high in the A1 and A2 horizons, and very high in the 2C horizon
Permeability: moderate to moderately rapid in the A1 and A2 horizons, and very rapid in the 2C horizon
Runoff: medium

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: crustose lichen, alpine azalea, reindeer lichen, Flavocetraria cucullata, eightpetal mountain-avens, Bigelow's sedge, star reindeer lichen, Cladina stygia, alpine sweetgrass, tomentypnum moss, Flavocetraria nivalis, white arctic mountain heather, moss, globe ball lichen, common woodrush, skeletonleaf willow, splendid feather moss, Schreber's big red stem moss, cup lichen, whiteworm lichen, Cladonia uncialis, witch's hair lichen, arctic bluegrass, alpine bearberry, black crowberry, lingonberry, rusty woodsia

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: 25 to 100 cm (10 to 39 in)

Umbric epipedon: 0 to 45 cm (0 to 18 in) (A1 and A2 horizons)

Lithologic discontinuity: 45 to 200 cm (18 to 79 in) (2C horizon)

ADDITIONAL DATA:

User pedon ID: 2021AK180605

---

National Cooperative Soil Survey
U.S.A.