LOCATION IYAGAK AK
Tentative Series
MJS/CBB
10/2024
IYAGAK SERIES
Depth class: very deep
Drainage class: well drained
Parent material: gravelly loamy colluvium derived from sedimentary rock
Landscape: mountains
Landform: mountain slopes
Slopes: 15 to 65 percent
Mean annual precipitation: about 450 mm (18 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 90 days
TAXONOMIC CLASS: Fragmental, mixed Typic Haplocryepts
TYPICAL PEDON: Iyagak silt in an alder, willow, and ericaceous scrub shrubland on an east facing concave, linear backslope on a slope of 52 percent at an elevation of 315 m (1035 ft)
Oe--0 to 7 cm (0 to 3 in); moderately decomposed plant material, dark reddish brown (5YR 2.5/2) moist, dark reddish gray (5YR 4/2) dry; many very fine and fine roots throughout; slightly acid (pH 6.5); clear smooth boundary. (0 to 8 cm, 0 to 3 in thick)
Oa--7 to 10 cm (3 to 4 in); highly decomposed plant material, dark reddish brown (5YR 2.5/2) moist, dark reddish gray (5YR 4/2) dry; many very fine, fine, and common medium roots throughout; neutral (pH 6.6); clear smooth boundary. (2 to 6 cm, 1 to 2 in thick)
A--10 to 20 cm (4 to 8 in); silt, very dark gray (10YR 3/1) moist, gray (10YR 5/1) dry; moderate medium subangular blocky structure; friable, slightly hard, slightly sticky, nonplastic; nonsmeary; few fine and medium roots throughout; very fine irregular pores; neutral (pH 6.8); clear smooth boundary. (8 to 15 cm, 3 to 6 in thick)
Bw--20 to 37 cm (8 to 15 in); gravelly silt, dark gray (2.5Y 4/1) moist, gray (2.5Y 6/1) dry; moderate medium subangular blocky structure; friable, slightly hard, slightly sticky, nonplastic; nonsmeary; few fine and medium roots throughout; very fine irregular pores; 30 percent gravel; neutral (pH 6.7); clear smooth boundary. (15 to 30 cm, 6 to 12 in thick)
C--37 to 200 cm (15 to 80 in); gravel; coarse and very coarse interstitial pores; 25 percent stones, 70 percent gravel. (141 to 175 cm, 56 to 69 in thick)
TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64 degrees 37 minutes 36.20 seconds north, longitude 160 degrees 9 minutes 36.55 seconds west, datum WGS84, UTM north 7167362.08 and UTM east 444531.21, 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: 2 to 14 cm (1 to 6 in)
Thickness of ochric epipedon: 10 to 20 cm (4 to 8 in)
Thickness of cambic horizon: 15 to 30 cm (6 to 12 in)
Oe and Oa horizons:
Hue: 5YR, 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 3
Texture: moderately decomposed plant material or highly decomposed plant material
Organic matter: 60 to 90 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
A horizon:
Hue: 10YR or 7.5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: silt or silt loam
Sand: 0 to 30 percent
Silt: 60 to 99 percent
Clay: 1 to 10 percent
Organic matter: 2 to 6 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
Bw horizon:
Hue: 2.5Y or 10YR
Value: 2 to 4 moist, 4 to 6 dry
Chroma: 1 to 2
Texture: silt loam, silt or their gravelly analogues
Sand: 0 to 35 percent
Silt: 53 to 97 percent
Clay: 3 to 12 percent
Rock fragments: 15 to 59 percent
Gravels: 15 to 59 percent
Organic matter: 0.5 to 3 percent
Reaction class: slightly acid to slightly alkaline (pH 6.1 to 7.8)
C horizon:
Texture: gravel
Rock fragments: 90 to 100 percent
Gravels: 60 to 95 percent
Cobbles: 0 to 35 percent
Organic matter: 0 percent
Some pedons have a folistic epipedon and/or do not have a cambic horizon.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Elevation: 100 to 550 meters (325 to 1805 feet)
Parent material: gravelly loamy colluvium derived from sedimentary rock
Landform: mountain slopes
Slopes: 15 to 65 percent
Mean annual precipitation: 300 to 500 mm (19 to 20 in)
Mean annual air temperature: -6 to -1 degrees C. (21 to 30 degrees F.)
Frost free period: 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Iyyagrik, Nunanjiak, Tui, Kikku, Tagluk, Aniruk, and Anugi soils.
Iyyagrik soils have a mollic epipedon and occur on similar landforms on the upper third of mountainflanks.
Nunanjiak soils spodic materials and andic soil properties and occur on similar landforms on linear, linear backslopes.
Tui soils have a lithologic discontinuity, a loamy-skeletal particle size class, and occur on similar landforms on nose slope positions.
Kikku soils have a fine-loamy particle size class, a gelic soil temperature regime, and occur on similar landforms on shoulder positions.
Tagluk soils have a mollic epipedon, a loamy-skeletal particle size class, and occur on similar landforms on backslopes.
Aniruk soils have a deep cambic horizon between 18 to 200 cm (7 to 80 in) and occur on similar landforms on nose slope positions.
Anugi soils have extremely cobbly and stony textures at depths between 4 to 170 cm (2 to 67 in), lithic contact at depths between 150 to 199 cm (59 to 78 in) and occur on similar landforms on side slope positions.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in the Oe and Oa horizons, moderately high in the A and Bw horizons, and very high in the C horizon
Permeability: rapid to very rapid in the Oe and Oa horizons, moderate in the A and Bw horizons, and very rapid in the C horizon
Runoff: high
USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: Schreber's big red stem moss, bog blueberry, dwarf birch, marsh Labrador tea, splendid feather moss, Siberian alder, black crowberry, tealeaf willow, resin birch, Beauverd spirea, bluejoint, meadow horsetail, reindeer lichen, and greygreen reindeer 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: 35 to 110 cm (14 to 43 in)
Ochric epipedon: 0 to 17 cm (0 to 7 in) (Oe, Oa, and A horizons)
Cambic horizon: 20 to 37 cm (8 to 15 in) (Bw horizon)
ADDITIONAL DATA:
User pedon ID: 2021AK180806
National Cooperative Soil Survey
U.S.A.