LOCATION INIGOK                  AK

Established Series
SDB/MJS
08/2026

INIGOK SERIES

Depth class: shallow
Drainage class: poorly drained
Parent material: organic material over eolian deposits
Landscape: coastal plains, and eolian coastal plains
Landform: string bogs, lake beds, incised streams and pattered ground
Microfeature: low relief domes of high-center polygons
Slope: 0 to 4 percent
Mean annual precipitation: about 130 mm (5 in)
Mean annual air temperature: about -11 degrees C (12 F)
Frost-free period: 22 to 82 days

TAXONOMIC CLASS: Sandy, mixed, pergelic Typic Histoturbels

TYPICAL PEDON: Inigok highly organic silt loam in a cottongrass and dwarf shrub community in the center of a high center low relief polygon at an elevation of 21 m. (70 ft)

Oi--0 to 3 cm (0 to 1 in); peat, dark brown (7.5YR 3/2) rubbed moist; nonsticky, nonplastic; moderately acid, (pH 5.6); clear wavy boundary

Oe--3 to 6 cm (1 to 2 in); mucky peat, very dark brown (7.5YR 2/2) rubbed moist; nonsticky, nonplastic; moderately acid, (pH 5.7); clear wavy boundary

Oa--6 to 8 cm (2 to 3 in); muck, very dark brown (7.5YR 2/2) rubbed moist; nonsticky, nonplastic; slightly acid, (pH 6.1); very abrupt wavy boundary

Cg--8 to 23 cm (3 to 9 in); highly organic silt loam, dark grayish brown (2.5Y 4/2) rubbed moist; massive; loose, slightly sticky, slightly plastic; common fine roots throughout; very fine tubular pores; distinct reddish brown (5YR 4/4) moist, masses of oxidized iron; strongly acid, (pH 5.4); very abrupt wavy boundary.

Oajj--23 to 38 cm (9 to 15 in); highly decomposed plant material, very dark brown (7.5YR 2.5/2) rubbed moist; nonsticky, nonplastic; few fine roots top of horizon; strongly acid, (pH 5.4); clear irregular boundary

Cg/Oajjf--38 to 80 cm (15 to 31 in); loamy very fine sand, muck, 40 percent brown (7.5YR 4/2) rubbed and 60 percent very dark brown (7.5YR 2.5/2) rubbed moist; massive; loose, nonsticky, nonplastic; olive brown (2.5Y 4/4), moist, masses of oxidized iron; slight effervescence; slightly acid, (pH 6.5); clear wavy boundary

Cgf--80 to 200 cm (31 to 79 in); loamy very fine sand, very dark gray (N 3/), rubbed moist; massive; loose, nonsticky, nonplastic; olive brown (2.5Y 4/4), moist, masses of oxidized iron; slight effervescence; slightly alkaline, (pH 7.4).

TYPE LOCATION: North Slope Borough County, Alaska: latitude 70.19467, longitude -152.10814, Datum WGS84

RANGE IN CHARACTERISTICS:

Soil moisture regime: aquic
Soil temperature regime: gelic
Mean annual soil temperature: -10 to -6 degrees C (14 to 21 degrees F)
Thickness of organic material: 8 cm (3 in)
Thickness of cryoturbated horizon: 30 cm (12 in)

Oi, Oe, or 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: 26 to 83 percent
Reaction class: strongly acid to neutral (pH 5.1 to 7.3)

Cg/Oajjf horizon:
Oa material: hue of 7.5YR or 10YR, value of 2 to 3, and chroma of 1 to 3
C material: hue of 10YR or 2.5Y, value of 4 to 5, chroma of 0 to 3
Texture: fine sand
Sand: 85 to 95 percent
Silt: 0 to 12 percent
Clay: 3 to 8 percent
Organic matter: 5 to 18 percent
Reaction class: strongly acid to neutral (pH 5.1 to 6.6)

C horizon:
Hue: 10YR or 2.5Y
Value: 4 to 5
Chroma: 0 to 3
Texture: fine sand
Sand: 85 to 95 percent
Silt: 0 to 12 percent
Clay: 3 to 8 percent
Organic matter: 0.1 to 1 percent
Reaction class: neutral to slightly alkaline (pH 6.6 to 7.8)

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 0 to 100 meters (0 to 330 ft)
Parent material: organic material over eolian deposits
Landform: string bogs, lake beds, incised streams and pattered ground
Slopes: 0 to 4 percent
Mean annual precipitation: 100 to 150 mm (4 to 6 in)
Mean annual air temperature: -12 to -11degrees C (10 to 12 degrees F)
Frost free period: 22 to 82 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anajuk, Bansheecreek, Nuiqsut, Pingok, Poleakoon, and Teshekpuk soils.
Anajuk soils are very poorly drained, have a histic epipedon, and occur on high centered polygons on patterned ground.
Bansheecreek soils are somewhat poorly drained, are organic soils, and occur on high relief domes of high-center polygons on relict lakebeds.
Nuiqsut soils are organic soils and occur on the center of low center polygons.
Pingok soils are organic soils and occur on the high relief troughs of high-center polygons.
Poleakoon soils lack cryoturbation, lack a glacic horizon, and occur on string bog, depressions, and drainageways.
Teshekpuk soils are well drained, have a mollic epipedon, lack permafrost, and occur on longitudinal dunes.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: poorly drained
Saturated hydraulic conductivity: high in the O horizons, low in the Cg/Oajjf and Cgf horizons
Permeability: moderately rapid in the O horizons, very slow in the Cg/Oajjf and Cgf horizons

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: tussock cottongrass and dwarf shrubs

DISTRIBUTION AND EXTENT: MLRA 246 Artic Coastal Plain
Extent: extensive

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

SERIES ESTABLISHED: National Petroleum Reserve- Beaufort Coastal Plain Area, Alaska, 2025

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

Particle size control section: 58 to 133 cm
Redox concentrations: 8 to 200 cm (3 to 79 in) (Cg, Oajj, Cg/Oajj, Cg/Oajjf and Cgf horizons)
Reduced matrix: 8 to 200 cm (3 to 79 in) (Cg, Oajj, Cg/Oajj, Cg/Oajjf and Cgf horizons)
Cryoturbation: 8 to 38 cm (3 to 15 in) (Oa/Cgjjf horizon)
Histic epipedon: 0 to 38 cm (0 to 15 in) (Oi, Oe, Oa, and Oajj horizons)
Permafrost: 32 to 200 cm (13 to 79 in) (Cg/Oajjf and Cgf horizons)

ADDITIONAL DATA:

User pedon Id: 2023AK185817

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National Cooperative Soil Survey
U.S.A.