LOCATION IIGUK                   AK

Established Series
MPS/SAS/TJR
05/2022

IIGUK SERIES

Landscape--hills, mountains
Landform--hillslopes, mountain slopes
Slope--1 to 45 percent
Parent material--loess and colluvium
Mean annual precipitation--about 550 mm
Mean annual air temperature--about -3 degrees C
Depth class--very deep
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--typic

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Typic Dystrocryepts

TYPICAL PEDON: Iiguk silt loam on a west facing convex, convex summit on a slope of 8 percent at an elevation of 237 m (The soil was moist throughout the profile when described on June 28, 2016.)

Oa--0 to 7 cm; highly decomposed plant material, brown (7.5YR 4/2) dry, very dark brown (7.5YR 2.5/2) moist; common very fine and fine roots; very strongly acid (pH 4.6); clear wavy boundary

A--7 to 15 cm; very gravelly silt loam, brown (7.5YR 4/3) dry, very dark brown (7.5YR 2.5/3) moist; weak medium subangular blocky parts to moderate fine granular structure; very friable; common very fine, fine, and medium roots; few fine irregular pores; 5 percent cobbles, 10 percent channers, 20 percent gravel; very strongly acid (pH 4.8); clear wavy boundary

Bw/Ajj--15 to 53 cm; very gravelly silt loam, 90 percent light yellowish brown (10YR 6/4) and 10 percent dark grayish brown (10YR 4/2) dry, 90 percent dark yellowish brown (10YR 4/4) and 10 percent very dark brown (10YR 2/2) moist; weak coarse subangular blocky parts to weak fine granular structure; very friable, nonsticky, slightly plastic; common very fine, fine, and medium roots; few fine irregular pores; 10 percent cobbles, 10 percent channers, 30 percent gravel; very strongly acid (pH 4.8); clear smooth boundary

C--53 to 150 cm; very gravelly silt loam, light yellowish brown (2.5Y 6/4) dry, olive brown (2.5Y 4/4) moist; massive; friable, nonsticky, slightly plastic; 10 percent fine faint dark gray (2.5Y 4/1) mottles and 10 percent fine distinct strong brown (7.5YR 4/6) masses of oxidized iron; 10 percent cobbles, 20 percent channers, 20 percent gravel; extremely acid (pH 4.4)

TYPE LOCATION: Nome Census Area, Alaska, latitude 63.5270920, longitude -160.9287430, datum WGS84 (Coordinates determined with a GPS unit)

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--0 to 3 degrees C
Soil moisture control section--dry less than 45 consecutive days in June through October
Thickness of ochric epipedon--7 to 20 cm
Thickness of cambic horizon--20 to 55 cm
Depth to redoximorphic iron concentrations--50 to 70 cm

Particle Size Control Section:
*Clay--2 to 12 percent
*Total fragments--35 to 75 percent gravels, channers, cobbles

Oa horizon
Thickness--2 to 10 cm

A horizon
Hue--7.5YR or 10YR
Value--2.5 or 3 moist, 4 or 5 dry
Chroma-2 to 4
Fine-earth texture--silt, silt loam
Clay--2 to 10 percent
Sand--5 to 25 percent
Organic carbon--5 to 12 percent
Total rock fragment content--26 to 75 percent
Total gravel content--20 to 50 percent
Total cobble content--0 to 20 percent
Total channer content--0 to 30 percent
Reaction--3.9 to 4.8
Thickness--5 to 15 cm

Bw/Ajj horizon
Hue--10YR or 2.5Y
Value--2 to 5 moist, 4 to 7 dry
Chroma--2 to 4
Fine-earth texture--silt loam, loam
Clay--5 to 10 percent
Sand--15 to 50 percent
Organic carbon--2 to 5 percent
Total rock fragment content--10 to 50 percent
Total gravel content--5 to 30 percent
Total cobble content--0 to 10 percent
Total channer content--0 to 10 percent
Reaction--4.3 to 5.6
Thickness--15 to 40 cm

C horizon
Value--3 or 4 moist, 5 or 6 dry
Chroma--2 to 4
Clay--5 to 12 percent
Sand--15 to 40 percent
Organic carbon--0.5 to 1.5 percent
Total rock fragment content--50 to 75 percent
Total gravel content--20 to 70 percent
Total cobble content--0 to 10 percent
Total channer content--0 to 40 percent
Reaction--4.4 to 5.8

COMPETING SERIES:
Northriver--no redoximorphic iron concentrations present, no mottles present; backslopes of mountains and hills

GEOGRAPHIC SETTING:
*Elevation--100 to 1000 m
*Climate--warm, moist summers; cold, dry winters
*Mean annual precipitation--370 to 745 mm
*Mean annual air temperature-- -5 to -1 degrees C
*Frost-free period--55 to 90 days

GEOGRAPHICALLY ASSOCIATED SOILS:
* Nunapik--permafrost present, histic epipedon, no cambic horizon, gelic soil temperature regime, aquic soil moisture regime, fine-loamy particle-size class, mounds on hillslopes or saddles of hills
*MountMcDonald--shallow to paralithic contact, umbric epipedon, udic soil moisture regime; ridges and mountain slopes

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
*Drainage class--well drained
*Saturation during normal years--saturated at a depth of between 50 and 75 cm for less than 2 weeks during the growing season
*Saturated hydraulic conductivity (Ksat)--very high in the surface organic layer, moderately high throughout the rest of the profile

USE AND VEGETATION:
Use--wildlife habitat, recreation, subsistence
Potential native vegetation--dwarf birch, bryocalon lichen, cetraria lichen, greygreen reindeer lichen, reindeer lichen, eightpetal mountain-avens, marsh Labrador tea, alpine azalea, tomenose lichen, arctic lupine, bog blueberry, lingonberry, Moss, witch's hair lichen, Bigelow's sedge, island cetraria lichen, pincushion plant, black crowberry, snow lichen

DISTRIBUTION AND EXTENT: Nulato Hills-Southern Seward Peninsula Highlands, Alaska; MLRA 240; moderate extent

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA

SERIES ESTABLISHED: Nulato Hills BLM area, Nome Census Area, Alaska; 2021

REMARKS:
Diagnostic horizons and features recognized in this pedon
*Particle-size control section--zone from 32 to 107 cm
*Ochric epipedon--zone from 0 to 15 cm
*Cambic horizon--zone from 7 to 53 cm
*Cryoturbation--zone from 15 to 53 cm
*Low chroma mottles--zone from 53 to 150 cm
*Redoximorphic concentrations--zone from 53 to 150 cm

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National Cooperative Soil Survey
U.S.A.