LOCATION TANACROSS               AK

Established Series
Rev. DKS/JPM/DLM
02/2022

TANACROSS SERIES

Depth class: shallow to moderately deep over permafrost
Drainage class: very poorly or poorly drained
Parent material: Organic matters over micaceous loamy alluvium, some pedons have a loess mantle over alluvium
Landform: flood plains, flood plains on alluvial flats, flood plains on alluvial fan or flood plains on terraces
Slope: 0 to 5 percent
Mean annual precipitation: 9 to 14 inches, 229 to 356 mm, approximately one third of which falls as snow
Mean annual temperature: 21 to 28 degrees F., -5 to -2.2 C.

TAXONOMIC CLASS:

TYPICAL PEDON: Tanacross peat - on a 0 percent slope under open black spruce forest at 1300 feet elevation. (All colors are for moist soil.)

Oi--0 to 9 inches, (0 to 23 cm); strong brown (7.5YR 5/6) peat; extremely acid (pH 4.0); clear wavy boundary. (8 to 16 inches thick)

A--9 to 15 inches, (23 to 38 cm); very dark gray (10YR 3/1) silt loam; weak coarse platy structure; firm; nonsticky and slightly plastic; common very fine to fine roots; moderately acid (pH 5.6); clear wavy boundary. (3 to 9 inches thick)

Bjjg--15 to 20 inches, (38 to 51 cm); very dark grayish brown (10YR 3/2 and 2.5Y 3/2) silt loam; common medium prominent strong brown (7.5YR 5/6) mottles; massive; firm, nonsticky and slightly plastic; moderately acid (pH 5.8); abrupt wavy boundary. (4 to 15 inches thick)

Bgf--20 to 29 inches, (51 to 74 cm); very dark grayish brown (2.5Y 3/2) perennially frozen silt loam; many coarse prominent yellowish brown (10YR 5/8) mottles; massive; extremely hard; moderately acid (pH 6.0). (6 to 15 inches thick)

Cf--29 to 60 inches, (74 to 152 cm); permanently frozen material

TYPE LOCATION: Gerstle River Area, Alaska; about 32 miles east-southeast of Delta Junction; SE 1/4 of the NE 1/4 of section 15, T.13S., R.15E.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature: less than 32 degrees F., 0 C.
Depth to permafrost: 10 to 40 inches, 25 to 102 cm below the mineral soil surface
Mineral soil: substantial mica, less than 25 percent
Particle size control section: greater than 15 percent fine sand or coarser; less than 18 percent clay.
Cryoturbation:
A and Bg horizons are usually mixed by cryoturbation

O horizon:
Texture: peat, mucky peat, or muck
Reaction class: extremely acid to moderately acid.

A horizon:
Matrix color: value of 2 to 4, chroma of 1 to 2
Texture: silt loam or mucky silt loam
Reaction class: strongly acid to slightly acid

Bg horizon:
Matrix color: hue of 10YR to 5Y, value of 3 to 5
Texture: stratas of silt loam, very fine sandy loam, fine sandy loam, or loamy fine sand
Reaction class: strongly acid to neutral

COMPETING SERIES: This is the Teggiuq series. Teggiuq soils lack visible mica in the solum.

GEOGRAPHIC SETTING:
Parent material: Organic matters over micaceous loamy alluvium, some pedons have a loess mantle over alluvium
Landform: flood plains, flood plains on alluvial flats, flood plains on alluvial fan or flood plains on terraces
Slope: 0 to 5 percent
Mean annual precipitation: 9 to 14 inches, 229 to 356 mm, approximately one third of which falls as snow
Mean annual temperature: 21 to 28 degrees F., -5 to -2.2 C.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Arrow, Moosehead and Gerstle soils. All of these soils soils are on similar landforms but lack permafrost.

DRAINAGE AND PERMEABILITY: Poorly or very poorly drained. Slow runoff. Saturated hydraulic conductivity is moderately high or high above the permafrost and is restricted by permafrost.

USE AND VEGETATION: Tanacross soils support sparse forests of stunted black spruce, with an understory of low shrubs and moss. Cleared areas, where permafrost has thawed, are occasionally used for small grains, forages, and vegetables.

DISTRIBUTION AND EXTENT: MLRA 229, Interior Alaska Lowlands. The series is of moderate extent.

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

SERIES ESTABLISHED: Gerstle River Area, Alaska, 1995

REMARKS: Diagnostic features and horizons include:
Moisture regime: aquic
Histic epipedon: 0 to 9 inches, 0 to 23 cm
Cryoturbation: 15 to 20 inches, 38 to 51 cm
Permafrost: 20 to 60 inches, 51 to 152 cm
Particle size control section (weighted average): coarse-loamy
Soil Reaction: greater than 5.5 (1:1 H2O) in the control section

Disturbance to the organic mat such as by burning or clearing will alter the thermal regime of the soil. Often, as a result, the permafrost and the water table will drop below the series control section.
Tanacross is the Alaska State Soil.

ADDITIONAL DATA: National Soil Survey Laboratory data S04AK-068-003 from Denali Borough, Alaska, samples by SSL Lincoln, NE, 07/04

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National Cooperative Soil Survey
U.S.A.