LOCATION CHUGACH AK
Established Series
GAH/DM
02/2022
CHUGACH SERIES
The Chugach series consists of very deep, well drained soils formed in a thin mantle of ash influenced loess overlying very gravelly glacial outwash. Chugach soils are on mountains and structural benches. Slopes range from 3 to 85 percent. The mean annual precipitation is about 35 inches, and the mean annual temperature is about 34 degrees F.
TAXONOMIC CLASS: Sandy-skeletal, mixed Andic Humicryods
TYPICAL PEDON: Chugach silt loam - on a southwest-facing slope of 23 percent at 2125 feet elevation. (All colors are for moist soil)
Oe--0 to 2 inches; moderately decomposed plant material; very strongly acid (pH 4.5); abrupt smooth boundary. (0 to 4 inches thick)
Oa--2 to 3 inches; highly decomposed plant material; very strongly acid (pH 4.5); abrupt smooth boundary. (0 to 4 inches thick)
E--3 to 4 inches; brown (7.5YR 5/2) silt loam; weak fine granular structure; very friable, slightly sticky and slightly plastic; common fine and medium roots; smeary; strongly acid (pH 5.4); abrupt smooth boundary. (1 to 3 inches thick)
Bhs--4 to 8 inches; dark brown (7.5YR 3/3) silt loam; weak fine granular; very friable, slightly sticky and slightly plastic; few fine roots; smeary; strongly acid (pH 5.2); clear smooth boundary. (1 to 5 inches thick)
Bs--8 to 11 inches; brown (7.5YR 4/4) silt loam; weak fine granular; very friable, slightly sticky and slightly plastic; few fine roots; slightly smeary; strongly acid (pH 5.2); clear smooth boundary. (2 to 6 inches thick)
2C--11 to 60 inches; very dark grayish brown (10YR 3/2) extremely gravelly loamy sand; massive; friable, nonsticky and nonplastic; 65 percent subrounded gravel; slightly acid (pH 6.4).
TYPE LOCATION: Anchorage Area, Alaska; about 8 miles east of Eklutana Lake campground in Thunderbird Valley, Alaska; in the SE 1/4 of the NW 1/4, section 10, T. 15N., R. 1 E.; Anchorage B6NW 1:25,000 quad, Seward Meridian; UTM north 6809679 and UTM east 0380010; zone 6.
RANGE IN CHARACTERISTICS: The ash influenced loess mantle ranges in thickness from 8 to 11 inches and may be bisequal. Depth to very gravelly outwash is 8 to 11 inches The upper 4 inches of the combined spodic horizons have more than 6 percent organic carbon. The silty mantle formed in loess dominated by amorphous material. Total coarse fragments in the solum ranges from 0 to 15 percent, 0 to 10 percent gravel and 0 to 5 percent cobbles. Depth to substratum ranges from 7 to 10 inches.
The E horizon has hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 1 or 2. The texture is silt, silt loam, or very fine sandy loam. Reaction is strongly acid or moderately acid.
The Bhs horizon has hue of 5YR or 7.5YR, value of 2 or 3, and chroma of 1 to 3. The texture is silt loam or very fine sandy loam. Reaction is strongly acid or moderately acid.
The Bs horizons have hue of 5YR or 7.5YR, and value and chroma of 3 or 4. The texture is silt loam or very fine sandy loam. Reaction is strongly acid or moderately acid.
The 2C horizon has hue of 10YR or 2.5Y, value of 4 or 5, and chroma of 2 or 3. The texture is loamy sand or sand modified by 35 to 70 percent gravel, 0 to 20 percent cobbles, and 0 to 3 percent stones. Reaction is moderately acid or slightly acid.
COMPETING SERIES: This is the
Klapatche series. Klapatche soils are moderately deep to highly weathered granodiorite.
GEOGRAPHIC SETTING: The Chugach soils occur on mountains and structural benches. Slopes range from 3 to 85 percent. The soils formed in a thin mantle of ash influenced loess, over gravelly glacial outwash. Mean annual temperature ranges from 25 to 40 degrees F. Mean annual precipitation ranges from 20 to 50 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These include
Talkeetna,
Deneka, and
Nakochna soils. Talkeetna soils have a loamy-skeletal substratum. Deneka soils are moderately deep to bedrock. Nakochna soils are higher on the landscape and are not underlain by glaciated materials.
DRAINAGE AND PERMEABILITY: Well drained. Medium to high runoff. Permeability is moderate in the loess mantle and rapid in the substratum.
USE AND VEGETATION: Wildlife habitat and recreation.
DISTRIBUTION AND EXTENT: Southcentral Alaska Mountains. The series is of small extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Anchorage Area, Alaska, 2001
REMARKS: Diagnostic features and horizons recognized in this profile include: albic horizon from 3 to 4 inches; spodic horizon from 4 to 10 inches; more than 6 percent organic carbon in the upper 4 inches of the spodic; amorphous material dominant from 4 to 10 inches; sandy-skeletal material in the control section; cryic temperature regime.
National Cooperative Soil Survey
U.S.A.