LOCATION GWICHIN AK
Established Series
JDP/DLM/TJR
05/2022
GWICHIN SERIES
Landscape--alluvial plains
Landform--stream terraces
Slope--0 to 3 percent
Parent material--alluvium
Mean annual precipitation--about 255 mm
Mean annual air temperature--about -6 degrees C
Depth class--very deep
Drainage class--moderately well drained
Soil moisture regime--udic
Soil temperature regime--gelic
Soil moisture subclass--typic
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid, subgelic Fluventic Haplorthels
TYPICAL PEDON: Gwichin silt loam on a forested terrace with a slope of 1 percent and an elevation of 128 m (The soil was moist throughout when described on June 24, 2010.)
Oi--0 to 10 cm; slightly decomposed plant material; many fine and medium roots; moderately acid (pH 6.0); clear smooth boundary
C1--10 to 17 cm; stratified silt loam; light brownish gray (2.5Y 6/2) dry, dark grayish brown (2.5Y 4/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine and medium roots, and common coarse roots; few fine and medium pores; neutral (pH 6.8); clear smooth boundary
A/C2--17 to 50 cm; stratified silt loam; 50 percent grayish brown (10YR 5/2) dry, very dark grayish brown (10YR 3/2) moist, and 50 percent grayish brown (2.5Y 5/2) dry, very dark grayish brown (2.5Y 3/2) moist; moderate medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine to coarse roots; common fine and medium pores; moderately alkaline (pH 8.3); clear smooth boundary
2C3--50 to 67 cm; stratified very fine sandy loam; light brownish gray (2.5Y 6/2) dry, dark grayish brown (2.5Y 4/2) moist; weak thin platy structure; soft, very friable, nonsticky and nonplastic; common fine roots; few fine and medium pores; 2 percent strong brown (7.5YR 4/6) moist, masses of oxidized iron throughout; strongly alkaline (pH 8.7); diffuse smooth boundary
2C4--67 to 78 cm; very fine sandy loam; light brownish gray (2.5Y 6/2) dry, dark grayish brown (2.5Y 4/2) moist; moderate thin platy structure; slightly hard, friable, nonsticky and nonplastic; 20 percent strong brown (7.5YR 4/6) moist, masses of oxidized iron throughout; strongly alkaline (pH 8.7); clear smooth boundary
2Cf--78 to 103 cm; permanently frozen very fine sandy loam; light brownish gray (2.5Y 6/2) dry, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, friable, nonsticky and nonplastic; 5 percent dark yellowish brown (10YR 4/6) moist, masses of oxidized iron throughout; strongly alkaline (pH 8.8)
TYPE LOCATION: Yukon-Koyukuk Census Area, Alaska; latitude 66.5508333 degrees, longitude -145.4575000 degrees, datum WGS84 (coordinates determined with a GPS)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature-- -4 to 1 degrees C
Depth to permafrost--70 to 100 cm
Depth to redoximorphic features--50 to 100 cm
Oi horizons
Thickness--5 to 10 cm
Reaction--6.0 to 7.5
Oe horizons (where present)
Thickness--5 to 10 cm
Reaction--6.0 to 7.5
A and A/C horizons (where present)
Hue--10YR, 7.5YR
Value--2 or 3 moist, 4 or 5 dry
Chroma--1 or 2 moist
Fine-earth texture--silt loam, very fine sandy loam, loam
Clay content--0 to 18 percent
Reaction--6.0 to 8.5
Effervescence--none to slight
Thickness--5 to 15 cm
BC horizons (where present)
Hue--10YR, 2.5Y
Value--2 to 4 moist, 4 to 6 dry
Chroma--1 or 2 moist
Fine-earth texture--silt loam, very fine sandy loam, fine sandy loam
Clay content--0 to 18 percent
Reaction--7.0 to 9.0
Effervescence--none to slight
Thickness--10 to 30 cm
C1, C2, 2C2, 2C3, and 2C4 horizons
Hue--10YR, 2.5Y
Value--2 to 4 moist, 4 to 6 dry
Chroma--1 or 2 moist
Fine-earth texture--silt loam, very fine sandy loam, fine sandy loam
Clay content--0 to 18 percent
Reaction--7.0 to 9.0
Effervescence--none to slight
Combined thickness--35 to 80 cm
2Cf horizon
Value--2 to 4 moist, 4 to 6 dry
Chroma--1 or 2 moist
Fine-earth texture--silt loam, very fine sandy loam, fine sandy loam
Clay content--0 to 18 percent
Reaction--7.0 to 9.0
Effervescence--none to strong
Thickness--50 to 80 cm
COMPETING SERIES:
None
GEOGRAPHIC SETTING:
Elevation--90 to 300 m
Climate--short, warm summers and long, very cold winters
Mean annual precipitation--210 to 310 mm
Mean annual air temperature-- -12 to 0 degrees C
Frost-free period--45 to 97 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Nuntragut--aquic conditions within 100 cm; similar landforms
Yasuda--aquic conditions within 25 cm; adjacent depressions on similar landforms; grassland vegetation
Tlozhavun--no aquic conditions within 150 cm; older surfaces on similar landforms
Tajittro--aquic conditions within 100 cm (moderately well drained); older surfaces on similar landforms
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--moderately well drained
Saturation in normal years--water table top depth between a depth of 50 to 75 cm in June
Flooding--rare
Ponding--none
Saturated hydraulic conductivity (Ksat)--high throughout
USE AND VEGETATION:
Use--wildlife habitat, subsistence, recreation
Potential natural vegetation--White spruce, quaking aspen, russet buffaloberry, prickly rose, grayleaf willow, twinflower, lingonberry, purple reedgrass, false toadflax, tall bluebells, Jakutsk snowparsley, sidebells wintergreen, eastern pasqueflower, splendid feather moss, Ptilidium liverwort, greygreen reindeer lichen, felt lichen, cup lichen
DISTRIBUTION AND EXTENT: Yukon Flats Lowlands, Alaska; MLRA 232; moderate extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Yukon Flats National Wildlife Refuge, Yukon-Koyukuk Census Area, Alaska; 2020
REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 35 to 110 cm
*Ochric epipedon
*Redoximorphic iron concentrations--2C3, 2C4, 2Cf horizons
*Permafrost--2Cf horizon
*Irregular decrease in organic carbon content--zone from 25 to 45 cm
A horizons may be thicker than 15 cm when buried, stratified, or otherwise mixed with B or C horizons; in these cases surface horizons do not meet criteria for mollic epipedons after mixing the upper 18 cm of mineral soil.
National Cooperative Soil Survey
U.S.A.