LOCATION INMACHUK                AK

Tentative Series
Rev. RBH/SR
02/2022

INMACHUK SERIES

These soils are made up of coarse fibrous sedge peat. They are perennially frozen at shallow depths.

TAXONOMIC CLASS: Dysic, subgelic Typic Fibristels

TYPICAL PEDON: Inmachuk peat - tundra. (Colors are for wet conditions)

0i1--0 to 2 inches; dark reddish brown (5YR 3/2) mat of coarse living mosses, sedges, and plant roots; very strongly acid; abrupt smooth boundary.

0i2--2 to 14 inches; black (5YR 2/1) fibrous coarse sedge peat with admixture of finely divided peat; 70 percent fiber rubbed; many roots; very strongly acid; clear smooth boundary.

0i3--14 to 16 inches; dark reddish brown (5YR 3/3) fibrous sedge peat with admixture of finely divided peat; 60 percent fiber rubbed; roots common; very strongly acid; clear smooth boundary.

0i4f--16 to 20 inches; same as 0i3 but frozen with clear ice lenses in late July.

TYPE LOCATION: Deering Area, Alaska. About 5 1/2 miles southwest of Deering and 1 3/4 miles west-northwest of River road.

RANGE IN CHARACTERISTICS: Depth to the permafrost table ranges from 15 to 20 inches. Lenses of silty muck may occur in the perennially frozen materials. Fibrous sedge peat generally makes up about 60 to 70 percent of the peaty materials. The surface of these soils is commonly characterized by high-centered polygons 20 to 30 feet in diameter. The troughs between the polygons average 3 to 5 feet across.

COMPETING SERIES: These include the Lemeta, Milroy, Salamatof, Saltery, and Staney series. The Lemeta soils consist of layered sphagnum and sedge peat over permafrost. The Milroy soils consist of partially decomposed sedge peat with many layers of tidal silt and sand. The Salamatof soils contain layered moss and sedge peat with no permafrost. The Saltery soils are made up of fibrous sedge peat with layers of volcanic ash, and with no permafrost. The Staney soils consist of partially decomposed sedge peat with no permafrost.

GEOGRAPHIC SETTING: The Inmachuk soils occupy shallow depressions, backwater portions of floodplains, and the beds of drained thaw lakes in tundra areas. The slope gradient is generally less than 1 percent. Many areas contain lakes and ponds. In most areas the water table is at or near the surface. Polygons are a characteristic feature, and pingos may occur. The climate is cold maritime with long, cold winters and short, cool summers. The average annual precipitation is less than 18 inches, and the average annual air temperature is less than 28 degrees F.

PRINCIPAL ASSOCIATED SOILS: These include the Milroy series, and the Kuskokwim and Sinuk series. The Kuskokwim soils have thick peaty surface mats overlying silty mineral materials with permafrost. The Sinuk soils are stratified sandy and silty soils on floodplains.

DRAINAGE AND PERMEABILITY: Very poorly drained with water perched on the permafrost table. Water is always at or near the surface of these soils.

USE AND VEGETATION: Mostly unused. The vegetation consists of sedges, dwarf birch, Labrador tea, and other low-growing shrubs and forbs.

DISTRIBUTION AND EXTENT: Northern Alaska. The series is probably of moderate extent.

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

SERIES PROPOSED: Deering Area, Alaska, 1967. (Origin of name is the Inmachuk River)

OSED scanned by SSQA. Last reviewed by state 3/70.

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National Cooperative Soil Survey
U.S.A.