LOCATION AULLASIK                AK

Tentative Series
SAS/CBB
10/2024

AULLASIK SERIES

Depth class: very deep
Drainage class: well drained
Parent material: loamy colluvium over gravelly loamy colluvium over residuum weathered from sandstone
Landscape: mountains
Landform: mountain slopes
Slopes: 30 to 85 percent
Mean annual precipitation: about 500 mm (19.68 in)
Mean annual air temperature: about -3 degrees C. (27 degrees F.)
Frost-free period: 70 to 90 days

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Spodic Humicryepts

TYPICAL PEDON: Aullasik highly organic silt loam in an alder community on an east facing linear, linear backslope on a slope of 69 percent at an elevation of 490 m (1608 ft)

Oi--0 to 6 cm (0 to 2 in); slightly decomposed plant material, very dark brown (7.5YR 2.5/2) moist, brown (7.5YR 5/2) dry; very fine, fine, medium, and coarse tubular pores; very strongly acid (pH 4.7); clear smooth boundary. (4 to 14 cm, 2 to 6 in thick)

A--6 to 9 cm (2 to 4 in); highly organic silt loam, very dark brown (7.5YR 2.5/2) moist, brown (7.5YR 5/2) dry; weak very fine granular structure; very friable, soft, nonsticky, nonplastic; nonsmeary; very fine, fine, medium, and coarse tubular and medium tubular pores; 3 percent cobbles, 7 percent gravels; extremely acid (pH 4.4); clear irregular boundary. (2 to 20 cm, 1 to 8 in thick)

Bhs--9 to 41 cm (4 to 16 in); gravelly silt loam, 80 percent very dark brown (7.5YR 2.5/3) and 20 percent very dark brown (7.5YR 2.5/2) moist, 80 percent brown (7.5YR 5/3) and 20 percent brown (7.5YR 5/2) dry; weak fine subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; weakly smeary; very fine, fine, medium, and coarse tubular pores; 5 percent cobbles, 15 percent gravels; very strongly acid (pH 4.9); clear irregular boundary. (18 to 35 cm, 7 to 14 in thick)

2Bw--41 to 62 cm (16 to 24 in); very gravelly silt loam, brown (10YR 4/3) moist, pale brown (10YR 6/3) dry; weak medium subangular blocky parting to weak medium granular structure; friable, slightly hard, slightly sticky, nonplastic; moderately smeary; very fine and fine tubular pores; 10 percent cobbles, 40 percent gravels; very strongly acid (pH 5.0); clear irregular boundary. (15 to 35 cm, 6 to 14 in thick)

2C--62 to 155 cm (24 to 61 in); extremely gravelly sandy loam, very dark grayish brown (2.5Y 3/2) moist, grayish brown (2.5Y 5/2) dry; structureless massive; slightly hard, friable, nonsticky, nonplastic; weakly smeary; very fine tubular pores; 10 percent cobbles, 55 percent gravel; strongly acid (pH 5.3). (75 to 96 cm, 30 to 38 in thick)

3R--155 to 180 cm (61 to 71 in); strongly coherent to indurated sandstone bedrock.

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64 degrees 14 minutes 33.17 seconds north, longitude 159 degrees 42 minutes 2.62 seconds west, datum WGS84, UTM north 7124229.53 and UTM east 466023.86, 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: 4 to 14 cm (2 to 6 in)
Thickness of umbric epipedon: 20 to 55 cm (8 to 22 in)
Thickness of cambic horizon: 15 to 35 cm (6 to 14 in)
Depth to lithologic discontinuity: 24 to 69 cm (9 to 27 in) and 114 to 195 cm (45 to 77 in)
Depth to lithic contact: 150 to 200 cm (60 to 79 in)

Oi horizon:
Hue: 7.5 YR or 10YR
Value: 2 to 2.5 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: slightly decomposed plant material
Organic matter: 60 to 90 percent
Reaction class: extremely acid to very strongly acid (pH 3.5 to 5.0)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 2.5 moist, 4 to 5 dry
Chroma: 1 to 3
Texture: silt loam, very fine sandy loam, silt, or their gravelly analogues
Sand: 10 to 65 percent
Silt: 22 to 80 percent
Clay: 2 to 13 percent
Rock fragments: 0 to 30 percent
Gravels: 0 to 25 percent
Cobbles: 0 to 5 percent
Organic matter: 10 to 19 percent
Reaction class: extremely acid to very strongly acid (pH 3.5 to 5.0)

Bhs horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 2 to 3
Texture: silt loam, silt, sandy loam or their gravelly analogues
Sand: 10 to 70 percent
Silt: 19 to 80 percent
Clay: 2 to 15 percent
Rock fragments: 15 to 50 percent
Gravels: 10 to 40 percent
Cobbles: 0 to 10 percent
Organic matter: 2 to 8 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.5)

2Bw horizon:
Hue: 10YR, 2.5Y or 5Y
Value: 3 to 4 moist, 5 to 6 dry
Chroma: 2 to 4
Texture: silt loam, loam or their gravelly analogues
Sand: 5 to 50 percent
Silt: 33 to 83 percent
Clay: 5 to 17 percent
Rock fragments: 15 to 55 percent
Gravels: 15 to 55 percent
Cobbles: 0 to 15 percent
Organic matter: 0.5 to 6 percent
Reaction class: very strongly acid to strongly acid (pH 4.5 to 5.5)

2C horizon:
Hue: 2.5Y, 5Y or 10YR
Value: 3 to 5 moist, 5 to 7 dry
Chroma: 1 to 4
Texture: sandy loam, silt loam, loam or their gravelly analogues
Sand: 35 to 80 percent
Silt: 5 to 50 percent
Clay: 5 to 15 percent
Rock fragments: 35 to 75 percent
Gravels: 30 to 65 percent
Cobbles: 0 to 20 percent
Organic matter: 0.4 to 3 percent
Reaction class: very strongly acid to moderately acid (pH 4.5 to 6.0)

3R horizon
Strongly coherent to indurated sandstone bedrock

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 250 to 550 meters (820 to 1804 feet)
Parent material: loamy colluvium over gravelly loamy colluvium over residuum weathered from sandstone
Landform: mountain slopes
Slopes: 30 to 85 percent
Mean annual precipitation: 400 to 600 mm (16 to 24 in)
Mean annual air temperature: -5 to -1 degrees C. (23 to 30 degrees F.)
Frost free period: 70 to 90 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nunanjiak, Atkaktut, and Niakuk soils.
Nunanjiak soils have andic soil properties at depths between 46 to 67 cm (10 to 20 in) and are underlain by paralithic bedrock.
Atkaktuk soils have a subgelic soil temperature regime and do not have a cambic horizon.
Niakuk soils are strongly smeary within the upper cambic horizon (12 to 24 cm, 5 to 9 in) and have an ochric epipedon.

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

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: Sitka alder, bluejoint, fireweed, spreading woodfern, larkspurleaf monkshood, and arctic starflower.

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: 31 to 106 cm (12 to 42 in)

Umbric epipedon: 6 to 41 cm (2 to 16 in) (A and Bhs horizons)

Cambic horizon: 41 to 62 cm (16 to 24 in) (2Bw horizon)

Lithologic discontinuity: 41 to 155 cm (16 to 61 in) (2Bw and 2C horizons) and 155 to 180 cm (61 to 70 in) (3R horizon)

Lithic contact: 155 to 180 cm (61 to 70 in) (3R horizon)

ADDITIONAL DATA:

User pedon ID: 2021AK290614

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National Cooperative Soil Survey
U.S.A.