LOCATION EGOOSIKCREEK AK
Established Series
SAS/MPS
04/2026
EGOOSIKCREEK SERIES
Depth class: very deep
Drainage class: well drained
Parent material: silty slope alluvium over gravelly loamy colluvium derived from sandstone
Landscape: mountains
Landform: swales
Slopes: 8 to 35 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 85 days
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, nonacid, subgelic Typic Haplogelolls
TYPICAL PEDON: Egoosikcreek silt loam in a willow subalpine community on an east facing linear, concave footslope on a slope of 18 percent at an elevation of 541m (1775 ft)
Oe--0 to 9 cm (0 to 4 in); moderately decomposed plant material; black (10YR 2/1) broken face moist, dark gray (10YR 4/1) broken face dry; many very fine, fine, coarse, common very coarse and few medium roots throughout; noneffervescent; strongly acid (pH 5.3); clear smooth boundary. (5 to 10 cm, 2 to 4 in thick)
A--9 to 47 cm (4 to 19 in); silt loam; black (7.5YR 2.5/1) broken face moist, dark gray (7.5YR 4/1) broken face dry; weak medium subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; moderately smeary; common very fine, fine, and few medium roots throughout; few fine tubular pores; 5 percent medium distinct irregular brown (7.5YR 4/4), moist, masses of oxidized iron in matrix; 3 percent gravel, 3 percent cobbles; negative to alpha-alpha dipyridyl; noneffervescent; moderately acid (pH 5.7); abrupt smooth boundary. (25 to 40 cm, 10 to 16 in thick)
2Bw1--47 to 90 cm (19 to 35 in); gravelly silt loam; dark grayish brown (10YR 4/2) broken face moist, light brownish gray (10YR 6/2) broken face dry; moderate fine granular structure; friable, slightly hard, slightly sticky, moderately plastic; nonsmeary; few very fine tubular pores; 25 percent gravel; negative to alpha-alpha dipyridyl; noneffervescent; moderately acid (pH 5.6); clear smooth boundary. (8 to 50 cm, 3 to 20 in thick)
2Bw2--90 to 115 cm (35 to 45 in); gravelly silty clay loam; very dark gray (10YR 3/1) broken face moist, gray (10YR 5/1) broken face dry; weak medium granular structure; friable, slightly hard, moderately sticky, moderately plastic; nonsmeary; common very fine tubular pores; 8 percent coarse prominent irregular strong brown (7.5YR 4/6), moist, masses of oxidized iron in matrix; 30 percent gravel; noneffervescent; strongly acid (pH 5.5); clear smooth boundary. (12 to 30 cm, 5 to 12 in thick)
2C1--115 to 130 cm (45 to 51 in); very gravelly loam; olive brown (2.5Y 4/3) broken face moist, light yellowish brown (2.5Y 6/3) broken face dry; massive; very friable, soft, nonsticky, nonplastic; nonsmeary; common fine tubular pores; 4 percent coarse prominent irregular strong brown (7.5YR 4/6), moist, masses of oxidized iron around rock fragments; 40 percent gravel; noneffervescent; strongly acid (pH 5.5); clear smooth boundary. (5 to 20 cm, 2 to 8 in thick)
2C2--130 to 200 cm (51 to 79 in); very gravelly loam; olive brown (2.5Y 4/3) broken face moist, light yellowish brown (2.5Y 6/3) broken face dry; massive; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; few very fine tubular pores; 55 percent gravel; negative to alpha-alpha dipyridyl; noneffervescent; moderately acid (pH 5.7)
TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64.7876740, longitude -159.5143980, datum WGS84, UTM north 7184890.91 and UTM east 475550.54, 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 organic material: 5 to 10 cm (2 to 4 in)
Thickness of mollic epipedon: 25 to 40 cm (10 to 16 in)
Thickness of cambic horizon: 20 to 80 cm (8 to 31 in)
Depth to redoximorphic concentrations: 5 to 10 cm (2 to 4 in)
Oe horizon:
Hue: 5YR, 7.5YR, 10YR
Value: 2 or 2.5 moist, 4 dry
Chroma: 1 to 3
Texture: moderately decomposed material
Organic matter: 60 to 90 percent
Reaction class: strongly acid to slightly acid (pH 5.1 to 6.5)
A horizon:
Hue: 7.5YR, 10YR, 2.5Y
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 or 2
Texture: silt, silt loam
Sand: 5 to 25 percent
Silt: 65 to 93 percent
Clay: 2 to 10 percent
Rock fragments: 0 to 10 percent
Gravels: 0 to 5 percent
Cobbles: 0 to 5 percent
Organic matter: 2 to 6 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
2Bw1 horizon:
Hue: 10YR or 2.5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 1 to 4
Texture: silt loam or its gravelly analogue
Sand: 10 to 30 percent
Silt: 50 to 80 percent
Clay: 18 to 25 percent
Rock fragments: 0 to 30 percent
Organic matter: 1 to 3 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
2Bw2 horizon:
Hue: 10YR, 2.5Y, 5Y
Value: 3 to 5 moist, 5 to 7 dry
Chroma: 1 to 4
Texture: silt loam, silty clay loam or their gravelly analogues
Sand: 5 to 30 percent
Silt: 50 to 80 percent
Clay: 18 to 30 percent
Rock fragments: 0 to 34 percent
Organic matter: 1 to 3 percent
Reaction class: strongly acid to slightly acid (pH 5.1 to 6.5)
2C1 horizon:
Hue: 2.5Y or 5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 2 to 4
Texture: loam, sandy loam or their gravelly analogues
Sand: 35 to 60 percent
Silt: 20 to 50 percent
Clay: 8 to 20 percent
Rock fragments: 15 to 50 percent
Organic matter: 0.4 to 2 percent
Reaction class: strongly acid to slightly acid (pH 5.1 to 6.5)
2C2 horizon:
Hue: 2.5Y or 5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 2 to 4
Texture: loam, sandy loam or their gravelly analogues
Sand: 30 to 60 percent
Silt: 20 to 50 percent
Clay: 10 to 25 percent
Rock fragments: 20 to 59 percent
Organic matter: 0.4 to 2 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
Some pedons have a mollic epipedon with a thickness ranging from 40 to 50 cm (16 to 20 in).
COMPETING SERIES: This is the
Tikigak (AK) series.
Tikigak soils have a loamy colluvium over gravelly loamy residuum parent material.
GEOGRAPHIC SETTING:
Elevation: 275 to 600 meters (905 to 1970 feet)
Parent material: silty slope alluvium over gravelly loamy colluvium derived from sandstone
Landform: swales
Slopes: 8 to 35 percent
Mean annual precipitation: 400 to 600 mm (16 to 24 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
Aklak,
Imak,
Imnak,
Kikku,
Sagvaktuk,
Silagiksaak,
Tatkik, and
Urgiilik 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), lack aquic conditions, lack a cambic horizon, have a fragmental particle size class, and occur on mountainflanks, upper and center thirds.
Imak soils have permafrost, have an organic surface thicker than 40 cm (16 in), lack a mollic epipedon, have an isotic mineralogy class, have a clay range of 5 to 20 percent, and occur on mountainbases, shoulders, backslopes, and footslopes.
Imnak soils have a paralithic contact at depths between 50 to 100 cm (20 to 40 in), have a fragmental layer starting at depths between 22 to 49 cm (9 to 19 in), lack aquic conditions, lack a cambic horizon, have a fragmental particle size class, have a cryic soil temperature regime, and occur on mountainflanks, upper and center thirds.
Kikku soils have a reduced matrix starting within 50 cm (20 in), have a histic epipedon, lack a cambic horizon, have free carbonates below 40 cm (16 in), and occur on shoulders and mountainflanks, upper third.
Sagvaktuk soils lack aquic conditions, have an ochric epipedon, have coarse-loamy particle size class, have an isotic mineralogy class, have a cryic soil temperature regime, and occur on drainageways in mountain valleys.
Silagiksaak soils have redox depletions with chroma of 2 or less starting within 65 cm (26 in), have an ochric epipedon, have a cryic soil temperature regime, and occur on mountainflanks, upper, center, and lower thirds.
Tatkik soils have a reduced matrix starting within 50 cm (20 in), have an ochric epipedon, have a loamy-skeletal particle size class, have a cryic soil temperature regime, have a clay range of 1 to 16 percent, and occur on similar landforms on swales.
Urgiilik soils have a lithic contact at depths between 50 to 100 cm (20 to 40 in), lack aquic conditions, have an ochric epipedon, have a loamy skeletal particle size class, have a cryic soil temperature regime, have a clay range of 4 to 12 percent, and occur on side slopes and mountainflanks, center third.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in the Oe horizon, moderately high in the A, 2Bw1, and 2Bw2 horizons, and moderately high to high in the 2C1 and 2C2 horizons
Permeability: rapid to very rapid in the Oe horizon, moderate in the A and 2Bw1 horizons, moderately slow to moderate in the 2Bw2 horizon, and moderate to rapid in the 2C1 and 2C2 horizons
Runoff: medium to high
USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: tealeaf willow, bluejoint, Richardson's willow, grass of Parnassus, artic sweet coltsfoot, arctic raspberry, splendid feather moss, seacoast angelica, Tilesius' wormwood, field horsetail, tall bluebells, yellow thimbleweed, boreal sagebrush, saxifrage, fireweed, tree climacium moss, tall Jacob's ladder, goose neck moss
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: 34 to 109 cm (13 to 43 in)
Mollic epipedon: 9 to 47 cm (4 to 22 in) (A horizon)
Redoximorphic concentrations: 9 to 47 cm (4 to 22 in) (A horizon)
Aquic conditions: 9 to 47 cm (4 to 22 in) (A horizon)
Cambic horizon: 47 to 115 cm (19 to 45 in) (2Bw1 and 2Bw2 horizons)
Lithologic discontinuity: 47 to 200 cm (19 to 79 in) (2Bw1, 2Bw2, 2C1, and 2C2 horizons)
Redoximorphic concentrations: 90 to 130 cm (35 to 51 in) (2Bw2 and 2C1 horizons)
Aquic conditions: 90 to 200 cm (35 to 79 in) (2Bw2, 2C1, and 2C2 horizons)
ADDITIONAL DATA:
User pedon ID: 2022AK290553
National Cooperative Soil Survey
U.S.A.