LOCATION KUSKOKWIM AK
Tentative Series
Rev. SR
02/2022
KUSKOKWIM SERIES
These soils have a thick mat of mosses and other organic materials over mottled silt loam. Under the natural vegetation, the permafrost table is very shallow.
TAXONOMIC CLASS:
TYPICAL PEDON: Kuskokwim silt loam - tundra (Colors are for moist conditions)
011 7-4" -- Mat of raw moss peat; many roots and woody fragments;clear smooth boundary.
012 4 Dark reddish brown (5YR 2/2) partially decomposed organic materials, mostly mosses; many roots; abrupt smooth boundary. 02
1-0" -- Black (5YR 2/1) finely divided organic matter; many roots; abrupt smooth boundary. All 0-3" -- Dark brown (7.5YR 3/2) silt loam; thin platy structure; few live roots; charcoal fragments and black streaks; frozen in early summer; very strongly acid; clear wavy boundary. A12 3-4" -- Dark graish brown (lOYR 4/2) silt loam; few mottles and streaks of reddish brown; thin platy structure; no live roots; frozen in early summer; very strongly acid; abrupt wavy oundary. Clgf 4-10" -- Dark gray (3Y 4/1) silt loam; ptches and streaks of dark grayish brown (2.5Y 4/2);and dark reish bron (5YR 3/2); perennially frozen with clear ice lenses; no roots; very strongly ac-d.
Type Location: Mcrath Area, Alaska. About 1 mile east of Takotna River,
3 miles northeast of McGrath.
Range in Characteristics: Depth to the permafrost table ranges from less than one inch to 12 inches under the natural vegetation; if the O horizon is removed, the permafrost table recedes to depths of several feet. The thickness of the n horizon ranges from 5 to 15 inches The A horizon
Page 2 Kuskokwim Series
may be absent or may be up to 4 inches thick. Matrix colorg range from 7.5YR 3/2 to lOYR 2/2. The C horizon is usually in hue 5Y; values range from 4 to 5, and chromas from 1 to 2. Buried organic materials, including woody pieces, may occur in the C horizon. Lenses of very fine sand and fine sand may occur, and gravel in places ranges up to 15% by volume.
Competing Series and their Differentiae: These include the Goldstream and Medfra series of the same family, the Easley, Kuslina, and Saulich. series of the same subgroup, and the Nome, Nushagak, and Tupuknuk series. The Goldstream soils are high in mica. The Medfra soils have olive and olive brown matrix colors. The Easley soils are calcareous. The Kuslina soils are nonacid and are sandy with silty strata. The Saulich soils are nonacid, are high in mica, and are modertely deep over bedrock. The Nome soils have thin O horizons and are gravelly. The Nushagak soils have thin O horizons and fairly thick A horizons, and are free of permafrost. The Tupuknuk soils have thin O horizons.
Setting: The Kuskokwim soils occur in a wide range of positions, including floodplains, terraces, and hilly uplands. The regolith is silty material extending below the permafrost table. The soils occur under cold continental and cold maritime climates. Mean annual air temperatures range from 18x to 28xF, and mean annual precipitation ranges from 12 to 25 inches.
Principal Associated Soils- These include the Kuslina, Nome, and Tupuknuk series, the Inmachuk, Lemeta, Sus tna, and Takotna series, and a wide range of well drained soils of uplands, including Cryorthents, Cryochrepts,
Kuskokwim SerieS Page 3
Cryumbrepts, and Cryorthods. The Inmachuk and Lemeta soils are deep Fibrists. The Susitna and Takotna soils are well drained stratified sandy and silty soils of floodplains.
Drainage and Permeability: Poorly drained. Internal drainage is blocked by permafrost.
Use and Vegetation: Nearly all in native vegetation, consisting of mosses, lichens, sedges, low-growing shrubs, and black spruce. In places, the soils support a forest of black spruce.
Distribution and Extent: Interior, western, and northern Alaska. The series is very extensive in the zones of continuous and discontinuous permafrost.
Series Proosed: McGrath Area, Alaska, 1964. (Source of name is the Kuskokwim River).
OSED scanned by NSSQA. Last revised by state 3/69.
National Cooperative Soil Survey
U.S.A.