LOCATION UMIAT                   AK

Inactive Series
Rev. CEF/SR
02/2022

UMIAT SERIES

These soils have thick O horizons, thin A1 horizons, and dark brown to dark grayish brown C horizons. The permafrost table is shallow.

TAXONOMIC CLASS:

TYPICAL PEDON: Umiat silt loam - tundra. (Colors are for moist conditions)

01--8 to 3 inches; dark reddish brown (5YR 2/2) partially decomposed hypnum moss; many roots; abrupt smooth boundary. (20 to 8 cm)

02--3 to 0 inches; black (5YR 2/1) well decomposed organic matter; many roots; very strongly acid; abrupt broken boundary. (8 to 0 cm)

A1f--0 to 3 inches; very dark grayish brown (10YR 3/2) silt loam; irregular streaks of black (10YR 2/1) organic matter; few coarse distinct mottles of dark brown (7.5YR 4/4); weak thin platy structure; nonplastic, nonsticky; moderately acid; frozen in midsummer; abrupt wavy boundary. (0 to 8 cm)

C1f--3 to 16 inches; dark grayish brown (10YR 4/2) silt loam; discontinuous vertical and horizontal lenses of very dark brown (10YR 2/2) and black (10YR 2/1) organic matter; frozen with thick clear ice lenses. (8 to 40 cm)

TYPE LOCATION: Umiat Area; Alaska. NE1/4 SE1/4, Sec. 5, T1S, R1W, Umiat Meridian.

RANGE IN CHARACTERISTICS: The O horizon ranges in thickness from 5 to 10 inches. The A horizon is in hue of 10YR to 5Y, with values of 2 or 3 and chroma from 1 to 3. It may or may not be mottled. The C horizon ranges in value from 3 to 4 and in chroma from 1 to 2. It commonly contains pockets and lenses of peat, and may be mottled.

COMPETING SERIES: These include the Copper River, Deborah, Kugrug, Kuslina, Saulich series of the same family, the Kuskokwim, Medfra, and Easley series of the same subgroup, and the Shivugak, Tanana, and Tupuknuk series. The Copper River soils have calcareous fine silty substrata. The Deborah soils are formed in gravelly sandy loam materials. The Kugrug soils consist of gravelly silt loam materials. The Kuslina soils are stratified. The Saulich soils are formed in silt loam materials with a high proportion of mica. The Kuskokwim soils are acid. The Medfra soils have high chromas in the control section and are acid. The Easley soils are calcareous. The Shivugak soils have no histic epipedon. The Tanana soils lack a histic epipedon and are high in mica. The Tupuknuk soils lack a histic epipedon and are acid.

GEOGRAPHIC SETTING: The Umiat soils occur on nearly level to steep slopes in areas with continuous or nearly continuous permafrost. The silty material is commonly underlain by sedimentary rock, which outcrops in places. Polygons are common. The climate is arctic, with long cold winters and short cool summers. Precipitation is less than 10 inches annually. Mean annual temperatures are less than 20 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Kuslina and Shivugak series, and the Tattitgak series. The Tattitgak soils have no histic epipedon and are stratified.

DRAINAGE AND PERMEABILITY: Poorly drained. Permeability is moderate above the permafrost. Runoff ranges from slow to rapid, depending on slope.

USE AND VEGETATION: The natural vegetation is arctic tundra; many areas are covered with sedge tussocks. The vegetation is interrupted in places by frost scars. The soils are used only by wildlife.

DISTRIBUTION AND EXTENT: Northern Alaska. The series is extensive.

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

SERIES PROPOSED: Umiat Area, Alaska, 1969. (Source of name is the settlement of Umiat).

OSED scanned by SSQA. Last revised by state 2/70.

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National Cooperative Soil Survey
U.S.A.