LOCATION TUPUKNUK                AK

Inactive Series
Rev. RBH/SR
02/2022

TUPUKNUK SERIES

These soils have thin organic surface mats overlying mottled dark gray silty alluvium with thin discontinuous streaks of peaty materials in some part. They are perennially frozen at about 20 inches.

TAXONOMIC CLASS:

TYPICAL PEDON: Tupuknuk silt loam, forest of alder and willows. (Colors are for moist conditions)

01--4 to 0 inches; dark reddish brown (5YR 2/2) mat partially decomposed organic matter with silty admixture; many roots, abrupt smooth boundary. (2 to 6 inches thick)

C1g--0 to 10 inches; dark gray (5Y 4/2) silt loam, with common medium distinct mottles of brown (10YR 4/3); weak thin platy structure: very friable; common roots; many thin lenses of sedge peat; strongly acid; clear smooth boundary. (4 to 16 inches thick)

C2g--10 to 14 inches; dark gray (N 4/ ) silt loam with common medium distinct mottles of dark reddish brown (5YR 3/4); weak thin platy structure; very friable; few roots; strongly acid; clear smooth boundary. (2 to 10 inches thick)

C3g--14 to 34 inches; dark gray (5Y 4/1) silt loam with common large distinct mottles of brown (10YR 4/3); weak very thin platy structure; very friable; no roots; frozen with clear ice lenses at 30 inches; strongly acid; gradual boundary. (10 to 24 inches thick)

C4fg--34 to 40 inches; dark gray (5Y 4/1) silt loam with common medium distinct reddish brown (5YR 4/4) mottles; frozen; no roots; strongly acid.

TYPE LOCATION: Bethel Area, Alaska, SE1/4 SE1/4, Sec. 2, T 8 N, R 71 W, Seward Meridian.

RANGE IN CHARACTERISTICS: Depth to the permafrost table ranges from 16 to 26 inches. Thin layers of organic matter, which consists of partially decomposed mosses, and sedges may occur at any depth. Thin discontinuous lenses of very fine sand, loam, and fine sand may occur. Matrix colors are in hues ranging from neutral to 2.5Y, in values of 3 or 4, and in chromas of 0 to 1. Few to many mottles dark reddish brown and brown commonly occur above the permafrost table.

COMPETING SERIES: These include the Napaishak series of the same family, the Batza, Bradway, Chisana, Tanana, and Yarger series of the same subgroup, and the Kuskokwim series. The Napaishak soils are mostly sandy. The Batza soils are formed in silty materials and lack buried organic strata. The Bradway and Tanana soils are high in mica and are nonacid. The Yarger soils have a fairly thick overburden of volcanic ash. The Chisana soils have developed in fine silty materials and are nonacid. The Kuskokwim soils are silty soils with a shallow permafrost table and a histic epipedon.

GEOGRAPHIC SETTING: The Tupuknuk soils occupy nearly level floodplains. The regolith is silty alluvium. Most areas contain overflow channels, sloughs, and abandoned stream channels. Flooding, especially during spring thaws, is common. The climate has characteristics of both maritime and continental conditions. Winters are long and cold, and summers are short and cool. The average annual air temperature ranges from 26 to 31 degrees F., and the average precipitation is between 17 to 22 inches.

DRAINAGE AND PERMEABILITY: Poorly drained. The water table is always at or near the surface. Moderate permeability above the permafrost table. Runoff is slow to very slow.

USE AND VEGETATION: The Tupuknuk soils are used chiefly by wildlife. The natural vegetation consists of willows, alder, bluejoint grass, horsetail, and associated plants.

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

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

SERIES PROPOSED: Bethel Area, Alaska. 1966. (Source of name is Tupuknuk Slough).

REMARKS: In the classification system formerly in use, these soils would have been included with the Low-Humic Gley soils.

OSED scanned by SSQA. Last revised by state on 11/67.

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National Cooperative Soil Survey
U.S.A.