LOCATION ISIMNJAATUK AK
Tentative Series
MJS/MPS
11/2024
ISIMNJAATUK SERIES
Depth class: deep to paralithic bedrock
Drainage class: well drained
Parent material: loess influenced gravelly loamy colluvium over gravelly loamy residuum weathered from graywacke
Landscape: mountains
Landform: mountain slopes
Slopes: 20 to 65 percent
Mean annual precipitation: about 500 mm (20 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 85 days
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, subgelic Typic Haplogelepts
TYPICAL PEDON: Isimnjaatuk channery silt loam in an alpine dwarf scrubland community on a northwest facing linear, convex backslope on a slope of 45 percent at an elevation of 686m (2251 ft)
Oe--0 to 6 cm (0 to 2 in); channery moderately decomposed plant material; very dark gray (10YR 3/1) moist, gray (10YR 5/1) dry; common very fine and fine roots throughout; 20 percent channers; moderately acid (pH 5.9); clear smooth boundary. (2 to 10 cm, 1 to 4 in thick)
A--6 to 11 cm (2 to 4 in); channery silt loam; dark brown (10YR 3/3) moist, brown (10YR 5/3) dry; moderate medium subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; common very fine and fine roots throughout; common medium dendritic tubular pores; 20 percent channers; moderately acid (pH 5.6); clear smooth boundary. (3 to 16 cm, 1 to 6 in thick)
Bw--11 to 35 cm (4 to 14 in); very flaggy silt loam; dark yellowish brown (10YR 3/4) moist, yellowish brown (10YR 5/4) dry; moderate medium subangular blocky structure; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; common very fine and common fine roots throughout; common medium dendritic tubular pores; 20 percent channers, 20 percent flagstones; moderately acid (pH 5.7); clear smooth boundary. (15 to 40 cm, 6 to 16 in thick)
2C--35 to 130 cm (14 to 51 in); very flaggy silt loam; dark grayish brown (2.5Y 4/2) moist, light brownish gray (2.5Y 6/2) dry; massive; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; common fine irregular pores; 20 percent channers, 20 percent flagstones; moderately acid (pH 5.9). (70 to 100 cm, 28 to 39 in thick)
2Cr--130 to 155 cm (51 to 61 in); moderately coherent graywacke bedrock.
TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64.318685, longitude -159.7964460, datum WGS84, UTM north 7132768.12 and UTM east 461489.16, 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: 2 to 10 cm (1 to 4 in)
Thickness of ochric epipedon: 3 to 16 cm (1 to 6 in)
Thickness of cambic horizon: 15 to 40 cm (6 to 16 in)
Depth to paralithic contact: 100 to 150 cm (40 to 60 in)
Oe horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 or 2
Texture: moderately decomposed material, or its channery analogue
Rock fragments: 0 to 25 percent
Organic matter: 60 to 90 percent
Reaction class: very strongly acid to slightly acid (pH 4.5 to 6.5)
A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 to 3
Texture: silt loam, fine sandy loam or their channery analogues
Sand: 10 to 65 percent
Silt: 23 to 80 percent
Clay: 2 to 12 percent
Rock fragments: 5 to 30 percent
Organic matter: 2 to 8 percent
Reaction class: moderately acid to slightly acid (pH 5.6 to 6.5)
Bw horizon:
Hue: 10YR
Value: 3 or 4 moist, 5 or 6 dry
Chroma: 2 to 4
Texture: silt loam, loam or their flaggy analogues
Sand: 10 to 65 percent
Silt: 33 to 80 percent
Clay: 6 to 17 percent
Rock fragments: 15 to 55 percent
Channers: 5 to 40 percent
Flagstones: 5 to 30 percent
Organic matter: 1 to 6 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
2C horizon:
Hue: 10YR or 2.5Y
Value: 3 to 4 moist, 5 or 6 dry
Chroma: 1 to 4
Texture: silt loam, sandy clay loam or their flaggy analogues
Sand: 25 to 65 percent
Silt: 5 to 69 percent
Clay: 6 to 30 percent
Rock fragments: 35 to 70 percent
Channers: 5 to 50 percent
Flagstones: 5 to 40 percent
Organic matter: 0.2 to 2 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
2Cr horizon:
Extremely weakly to moderately coherent graywacke bedrock.
Some pedons have a paralithic contact starting at depths of 90 cm (35 in).
COMPETING SERIES: This is the Kalasikcreek (AK) series.
Kalasikcreek soils have a paralithic contact at depths between 50 to 100 cm (20 to 40 in), and have a mean annual precipitation range of 400 to 600 mm (16 to 24 in)
GEOGRAPHIC SETTING:
Elevation: 500 to 900 meters (1640 to 2955 feet)
Parent material: loess influenced gravelly loamy colluvium over gravelly loamy residuum weathered from graywacke
Landform: mountain slopes
Slopes: 20 to 65 percent
Mean annual precipitation: 500 to 600 mm (20 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
Aullasik,
Debauch,
Iyyagrik,
Kanik,
Kikku,
Managaarak,
Niakuk,
Nunanjiak,
Savik,
Sikuruk,
Tui soils.
Aullasik soils have a lithic contact at depths between 150 to 200 cm (60 to 79 in), have an umbric epipedon, have a clay range of 2 to 17 percent, have a cryic soil temperature regime, and occur on mountainflanks, center third
Debauch soils have a paralithic contact at depths between 25 to 50 cm (10 to 20 in), lack a cambic horizon, have a clay range of 3 to 12 percent, and occur on ridges
Iyyagrik soils have lithic contact at depths between 100 to 150 cm (40 to 60 in), have a mollic epipedon, lack a cambic horizon, have a clay range of 2 to 12 percent, have a cryic soil temperature regime, and occur on similar landforms on mountainflanks, upper third
Kanik soils have lithic contact at depths between 100 to 150 cm (40 to 60 in), have a fragmental layer starting at depths between 66 to 100 cm (26 to 40 in), lack a cambic horizon, have a clay range of 3 to 18 percent, and occur on mountainflanks, upper and center thirds
Kikku soils have aquic conditions starting between 0 to 25 cm (0 to 10 in), have a histic epipedon, lack a paralithic contact within 200 cm (79 in), lack a cambic horizon, have free carbonates starting below 40 cm (16 in), have a fine-loamy particle size class, and occur on shoulders and mountainflanks, upper third
Managaarak soils have 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), lack a cambic horizon, have an acid reaction class, have a clay range of 2 to 15 percent, and occur on similar landforms on mountainflanks, upper third
Niakuk soils have lithic contact at depths between 100 to 150 cm (40 to 60 in), have a fragmental layer starting at depths between 20 to 73 cm (8 to 29 in), have a coarse-loamy over fragmental particle size class, and occur on mountainflanks, upper and center thirds
Nunanjiak soils have a folistic epipedon, have an umbric epipedon, 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 head slopes and mountainflanks, center third
Savik soils have a paralithic contact at depths between 25 to 50 cm (10 to 20 in), have a fragmental layer starting at depths between 13 to 39 cm (5 to 15 in), have an umbric epipedon, lack a cambic horizon, have a fragmental particle size class, and occur on knife ridges on nose slopes and mountainflanks, upper third
Sikuruk soils have permafrost, have aquic conditions starting between 0 to 25 cm (0 to 10 in), lack a paralithic contact within 200 cm (79 in), have an organic surface thicker than 40 cm (16 in), and occur on saddles, shoulders, summits, and mountainflanks, center third
Tui soils lack a paralithic contact within 200 cm (79 in), have a clay range of 3 to 17 percent, have a cryic soil temperature regime, and occur on nose slope and mountainflanks
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in the Oe horizon, moderately high to high in the A and Bw horizons, and moderately high in the 2C horizon
Permeability: rapid to very rapid in the Oe horizons, moderate to rapid in the A and Bw horizons, and slow to moderate in the 2C horizon
Runoff: high
USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: eightpetal mountain-avens, Flavocetraria cucullate, black crowberry, alpine bearberry, boreal sagebrush, cetraria lichen, willow, tomentypnum moss, greygreen reindeer lichen, dicarium moss, lingonberry, Sitka alder, cup lichen
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)
Ochric epipedon: 0 to 11 cm (0 to 4 in) (A horizon)
Cambic horizon: 11 to 35 cm (4 to 14 in) (Bw horizon)
Lithologic discontinuity: 35 to 155 cm (14 to 61 in) (2C and 2Cr horizons)
Paralithic contact: 130 to 155 cm (51 to 61 in) (2Cr horizon)
ADDITIONAL DATA:
User pedon ID: 2022AK290637
National Cooperative Soil Survey
U.S.A.