LOCATION GULKANA                 AK

Established Series
Rev. MHC/JPM/DLM
05/2022

GULKANA SERIES

The Gulkana series consists of very deep, well drained soils formed in a mantle of silty loess over gravelly alluvium on stream terraces. Slopes range from 0 to 20 percent. Mean annual temperature is about 26 degrees F., and mean annual precipitation is about 12 inches.

TAXONOMIC CLASS: Coarse-silty over sandy or sandy-skeletal, mixed, superactive Typic Haplocryepts

TYPICAL PEDON: Gulkana silt loam - on a 1 percent slope under quaking aspen at 1100 feet elevation. When described, the soil was moist throughout.

Oi--3 inches to 0; very dark brown (10YR 2/2) undecomposed mat of moss, leaves and other forest litter; abrupt smooth boundary. (1 to 3 inches thick)

A--0 to 1 inch; very dark grayish brown (10YR 3/2) silt loam, brown (10YR 5/3) dry; moderate fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, common medium, and few coarse roots; 5 percent well rounded gravel; neutral (pH 6.6); clear smooth boundary. (1 to 7 inches thick)

Bw1--1 to 4 inches; dark yellowish brown (10YR 3/4) silt loam, yellowish brown (10YR 5/4) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine, few medium and coarse roots; 5 percent well rounded gravel; neutral (pH 6.8); clear wavy boundary. (4 to 13 inches thick)

Bw2--4 to 14 inches; dark grayish brown (10YR 4/2) silt loam, grayish brown (10YR 5/2) dry; many medium and large faint dark yellowish brown (10YR 3/4) mottles, yellowish brown (10YR 5/4) dry; weak very thin platy structure; soft, very friable, nonsticky and nonplastic; few very fine, fine and medium roots; 5 percent well rounded gravel; neutral (pH 7.0); clear wavy boundary. (6 to 10 inches thick)

2C1--14 to 36 inches; variegated very gravelly sand; variable colors dominated by very dark gray (10YR 3/1); single grain; loose, nonsticky and nonplastic; few very fine roots; 40 percent well rounded gravel and 10 percent well rounded cobble; slightly alkaline (pH 7.8); abrupt wavy boundary. (2 to 26 inches thick)

2C2--36 to 43 inches; dark grayish brown (2.5Y 4/2) fine sand; single grain; loose, nonsticky and nonplastic; few very fine roots; 10 percent well rounded gravel; slightly alkaline (pH 7.8); abrupt wavy boundary. (0 to 10 inches thick)

2C3--43 to 52 inches; variegated very gravelly fine sand; colors dominated by very dark gray (10YR 3/1); single grain; loose, nonsticky and nonplastic; 40 percent well rounded gravel and 10 percent well rounded cobble; carbonate coatings on undersides of coarse fragments; slightly alkaline (pH 7.8); clear smooth boundary. (0 to 12 inches thick)

2C4--52 to 60 inches; variegated very cobbly sand; variable colors dominated by very dark gray (10YR 3/1); single grain; loose, nonsticky and nonplastic; 25 percent well rounded gravel and 20 percent well rounded cobble; carbonate coatings on the undersides of coarse fragments; slightly alkaline (pH 7.8).

TYPE LOCATION: Copper River Area, Alaska; 1/2 mile west of Copper Center; about 800 feet west and 600 feet south of the NE corner of section 13, T.1N., R.1E., Copper River Meridian.

RANGE IN CHARACTERISTICS: MAST ranges from 32 to 35 degrees F. Thickness of the solum ranges from 6 to 16 inches. Texture of the upper part of the particle size control section is silt loam, silt or very fine sandy loam with less than 15 percent fine sand or coarser. Texture of the lower part of the control section is dominantly fine sand or sand. Depth to the contrasting sandy and gravelly material is 12 to 30 inches. Coarse fragment content of the lower control section ranges from 35 to 75 percent. Reaction is neutral to mildly alkaline in the solum and neutral to moderately alkaline in the substratum.

The A horizon has moist hue of 7.5YR or 10YR; moist value of 2, 3 or 4; and moist chroma of 1, 2 or 3. Colors often occur in horizontal and convoluted streaks and patches. Texture is silt, silt loam or very fine sandy loam.

The Bw horizons have moist hue of 7.5YR or 10YR; moist value of 3 or 4; and moist chroma of 2, 3 or 4. Colors often occur in horizontal and convoluted streaks and patches. Texture is silt loam, silt or very fine sandy loam. Cobble and gravel content is less than 5 percent.

A C horizon may be present in some pedons. Moist hue ranges from 10YR to 5Y; most value from 3 to 5; and moist chroma from 2 to 4. Texture is silt loam, silt or very fine sandy loam. Cobble and gravel content is less than 10 percent. Thickness ranges from 0 to 14 inches.

The 2C horizons have moist hue from 10YR to 5Y; moist value from 1 to 4; and moist chroma from 1 to 4. Colors are variegated and dark due to the high content of black sand grains. Textures include sand and fine sand. Coarse fragment content ranges from 35 to 75 percent with 35 to 75 percent gravel and 0 to 30 percent cobble. Lime coatings are present on the undersides of many coarse fragments.

COMPETING SERIES: These are the Knik, Nenana and Yensus series. Knik and Yensus soils lack calcium carbonate is the substratum. Nenana soils have substantial mica content and lack free calcium carbonate.

GEOGRAPHIC SETTING: Gulkana soils formed in a loess mantle over sandy and gravelly alluvium on stream terraces. Slopes range from 0 to 20 percent. The climate is subarctic continental with long, cold winters and short, warm summers. Mean annual precipitation ranges from 8 to 17 inches, and the mean annual snowfall is 39 to 68 inches. Mean January temperature is minus 10 degrees F., mean July temperature is 56 degrees F., and the mean annual temperature varies from 23 to 27 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Copper River and Nizina soils. Copper River soils have thick organic mats and permafrost and are on high lacustrine terraces and glacial till plains. Nizina soils are very shallow to sand and gravel and are on floodplains and low stream terraces.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is slow. Permeability is moderate in the loess mantle and rapid in the sand and gravel.

USE AND VEGETATION: Most areas have native vegetation of white spruce, quaking aspen, low shrubs and mosses.

DISTRIBUTION AND EXTENT: Copper River Basin, Alaska. The series is of moderate extent.

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

SERIES ESTABLISHED: Copper River Area, Alaska. 1986.

REMARKS: Diagnostic features and horizons recognized in this pedon include: a cambic horizon from 1 to 14 inches; coarse silty particle size from 0 to 14 inches and sandy-skeletal particle size from 14 to 60 inches; a cryic temperature regime.

ADDITIONAL DATA: Laboratory data is available for this soil: NSSL number 81P4116-4121.

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National Cooperative Soil Survey
U.S.A.