LOCATION AMIGAK AK
Tentative Series
SAS/CBB
10/2024
AMIGAK SERIES
Depth class: very deep
Drainage class: poorly drained
Parent material: organic material over loamy slope alluvium derived from graywacke
Landscape: hills
Landform: hillslopes
Slopes: 3 to 15 percent
Mean annual precipitation: about 400 mm (15.75 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 90 days
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, nonacid, subgelic Histic Gelaquepts
TYPICAL PEDON: Amigak peat in a black spruce open forest on an east facing convex, linear backslope on a slope of 9 percent at an elevation of 115 m (377 ft)
Oi--0 to 18 cm (0 to 7 in); peat, brown (7.5YR 4/4) broken face moist, light brown (7.5YR 6/4) broken face dry; many very fine and coarse, common fine, and few medium roots throughout; strongly acid (pH 5.1); clear smooth boundary (12 to 22 cm, 5 to 9 in thick)
Oe--18 to 27 cm (7 to 11 in); mucky peat, black (10YR 2/1) broken face moist, dark gray (10YR 4/1) broken face dry; many very fine and common fine roots throughout; slightly acid (pH 6.5); clear smooth boundary (8 to 15 cm, 3 to 6 in thick)
Ajjg--27 to 48 cm (11 to 19 in); silt loam, 50 percent black (7.5YR 2.5/1) broken face and 30 percent very dark grayish brown (10YR 3/2) broken face and 20 percent dark grayish brown (10YR 4/2) broken face moist, 50 percent dark gray (7.5YR 4/1) broken face and 30 percent grayish brown (10YR 5/2) broken face and 20 percent light brownish gray (10YR 6/2) broken face dry; weak coarse granular structure; friable, slightly hard, nonsticky, nonplastic; weakly smeary; many very fine and few fine roots throughout; very fine irregular pores; 3 percent medium, distinct, lenticular, noncoherent dark brown (7.5YR 3/4), moist, masses of oxidized iron with clear boundaries in matrix; neutral (pH 6.7); clear irregular boundary. (2 to 25 cm, 1 to 10 in thick)
Bg1--48 to 68 cm (19 to 26.8 in); silt loam, dark gray (5Y 4/1) broken face moist, gray (5Y 6/1) broken face dry; moderate thin platy structure; slightly hard, friable, slightly sticky, moderately plastic; nonsmeary; common very fine roots throughout; very fine irregular pores; 25 percent medium, prominent, irregular, noncoherent dark brown (7.5YR 3/4), moist, masses of oxidized iron with clear boundaries in matrix; 10 percent gravel; neutral (pH 7.1); clear smooth boundary. (8 to 25 cm, 3 to 10 in thick)
Bg2--68 to 95 cm (26.8 to 37 in); loam, very dark gray (5Y 3/1) broken face moist, gray (5Y 5/1) broken face dry; weak very fine granular structure; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; few very fine roots throughout; very fine irregular pores; 10 percent coarse, prominent, irregular, noncoherent dark yellowish brown (10YR 4/4), moist, masses of oxidized iron with clear boundaries in matrix; 10 percent gravel; neutral (pH 7.1); clear smooth boundary. (20 to 40 cm, 8 to 16 in thick)
Cg--95 to 200 cm (37 to 79 in); gravelly loam, dark grayish brown (2.5Y 4/2) broken face moist, light brownish gray (2.5Y 6/2) broken face dry; structureless massive; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; very fine irregular pores; 50 percent fine, distinct, irregular, noncoherent dark yellowish brown(10YR 4/4), moist, masses of oxidized iron with clear boundaries in matrix; 20 percent gravel; neutral (pH 7.3). (73 to 150 cm, 29 to 59 in thick)
TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 65 degrees 14 minutes 19.59 seconds north, longitude 161 degrees 4 minutes 22.15 seconds west, datum WGS84, UTM north 7236657.35 and UTM east 403139.83, zone 4W, datum WGS84.
RANGE IN CHARACTERISTICS:
Soil moisture regime: aquic
Soil temperature regime: gelic
Mean annual soil temperature: -1 to 0 degrees C. (30 to 32 degrees F.)
Thickness of organic material: 20 to 37 cm (8 to 15 in)
Thickness of histic epipedon: 20 to 37 cm (8 to 15 in)
Thickness of cambic horizon: 30 to 90 cm (12 to 35 in)
Depth to redoximorphic concentrations: 20 to 37 cm (8 to 15 in)
Depth to reduced matrix: 22 to 62 cm (9 to 24 in)
Depth to cryoturbation: 20 to 37 cm (8 to 15 in)
Oi horizon:
Hue: 7.5YR or 10YR
Value: 2 to 4
Chroma: 1 to 4
Texture: peat
Organic matter: 60 to 90 percent
Reaction class: extremely acid to slightly acid (pH 3.5 to 6.5)
Oe horizon:
Hue: 10YR, 7.5YR, or 5YR
Value: 2 to 3
Chroma: 1 to 2
Texture: mucky peat
Organic matter: 60 to 90 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
Ajjg horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 2 to 4 moist, 4 to 6 dry
Chroma: 1 to 3
Texture: silt loam or silt
Sand: 5 to 25 percent
Silt: 63 to 91 percent
Clay: 4 to 12 percent
Organic matter: 2 to 4 percent
Reaction class: slightly acid to neutral (pH 6.1 to 7.3)
Bg1 horizon:
Hue: 5Y, 10Y, or 2.5Y
Value: 3 to 4 moist, 5 to 6 dry
Chroma: 0 to 2
Texture: silt loam or silty clay loam
Sand: 5 to 30 percent
Silt: 48 to 79 percent
Clay: 16 to 32 percent
Rock fragments: 0 to 14 percent
Gravels: 0 to 14 percent
Organic matter: 1 to 3 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
Bg2 horizon:
Hue: 5Y or 2.5Y
Value: 3 to 5 moist, 5 to 7 dry
Chroma: 1 to 3
Texture: loam or silty clay loam
Sand: 5 to 40 percent
Silt: 33 to 68 percent
Clay: 18 to 35 percent
Rock fragments: 0 to 14 percent
Gravels: 0 to 14 percent
Organic matter: 1 to 3 percent
Reaction class: slightly acid to neutral (pH 6.1 to 7.3)
Cg horizon:
Hue: 2.5Y or 5Y
Value: 4 to 5 moist, 6 to 7 dry
Chroma: 1 to 2
Texture: loam, silt loam, or their gravelly analogues
Sand: 15 to 35 percent
Silt: 42 to 69 percent
Clay: 16 to 23 percent
Rock fragments: 0 to 25 percent
Gravels: 0 to 25 percent
Organic matter: 0.4 to 2 percent
Reaction class: slightly acid to slightly alkaline (pH 6.1 to 7.8)
Some pedons have a coarse-loamy particle size class and/or free carbonates at depths greater than 140 cm (55 in).
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Elevation: 50 to 450 meters (165 to 1,475 feet)
Parent material: organic material over loamy slope alluvium derived from graywacke
Landform: hillslopes
Slopes: 3 to 15 percent
Mean annual precipitation: 300 to 500 mm (12 to 20 in)
Mean annual air temperature: -7 to -1 degrees C. (19 to 30 degrees F.)
Frost free period: 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Uluun, Siksrik,
Agitchuk, Anugi, and
Imak soils.
Uluun soils have a folistic epipedon, a cryic temperature regime, and occur on similar landforms on backslope positions.
Siksrik soils have an ochric epipedon, are well drained, and occur on similar landforms on backslope and footslope positions.
Agitchuk soils have a coarse-loamy particle size class, an acid reaction class, and occur on similar landforms on backslope, footslope, and toeslope positions.
Anugi soils have an ochric epipedon, a loamy-skeletal particle size class, and occur on mountain slopes.
Imak soils have permafrost within 100 cm (40 in) and occur on similar landforms on footslope positions.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: poorly drained
Saturated Hydraulic Conductivity: moderately high to high in the Oi, Oe, Bg2, and Cg horizons; modeately high in the Ajjg and Bg1 horizons
Permeability: moderate to moderately rapid in the Oi, Oe, and Cg horizons; moderate in the Ajjg horizon; slow to moderate in the Bg1 horizon; and slow to moderately rapid in the Bg2 horizon
Runoff: very high
USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: woodland horsetail, Schreber's big red stem moss, black spruce, bog blueberry, arctic sweet coltsfoot, marsh Labrador tea, cloudberry, moss, tealeaf willow, sphagnum, field horsetail, black crowberry, lingonberry, splendid feather moss, aulacomnium moss, reindeer lichen, cup lichen, greygreen reindeer lichen, cetraria lichen, cup lichen, felt lichen, dwarf birch, and bluejoint.
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: 52 to 127 cm (20 to 50 in)
Histic epipedon: 0 to 27 cm (0 to 11 in) (Oi and Oe horizons)
Cambic horizon: 27 to 95 cm (11 to 37 in) (Ajgg, Bg1, and Bg2 horizons)
Redoximorphic concentrations: 27 to 200 cm (11 to 79 in) (Ajgg, Bg1, Bg2, and Cg horizons)
Aquic conditions: 0 to 200 cm (0 to 79 in)
ADDITIONAL DATA:
User pedon ID: 2023AK180240
National Cooperative Soil Survey
U.S.A.