LOCATION HELM                    AK

Established Series
Rev:WDL/CSC/JPM
05/2022

HELM SERIES

The Helm series consists of shallow to bedrock, very poorly drained soils formed in residuum and colluvium from phyllite, schist, sedimentary, or granitic rocks. Helm soils are on backslopes and benches of hills and mountains. Slopes range from 5 to 120 percent. Mean annual precipitation is about 120 inches and mean annual temperature is about 46 degrees F.

TAXONOMIC CLASS: Loamy, mixed, superactive, acid Histic Lithic Cryaquepts

TYPICAL PEDON: Helm muck--on an E facing slightly concave slope of 20 percent under conifer forest vegetation at 1500 feet elevation. (All colors are for moist soil)

Oa--8 to 0 inches; very dusky red (2.5YR 2.5/2) muck; well decomposed organic matter; common very fine, fine, medium, and coarse roots. (8 to 10 inches thick)

A--0 to 3 inches; dark gray (10YR 4/1) silt loam; weak medium subangular blocky structure; very friable; slightly sticky and slightly plastic; few fine and common coarse roots; very strongly acid (pH 4.8); abrupt smooth boundary. (1 to 3 inches thick)

Cg--3 to 10 inches; gray (10YR 5/1) channery silt loam; massive; friable; slightly sticky and slightly plastic; common medium distinct mottles of strong brown (7.5YR 5/8); few fine and common coarse roots; 30 percent channers; very strongly acid (pH 4.8); abrupt smooth boundary.

R--10 inches; phyllite bedrock

TYPE LOCATION: Ketchikan Survey Area, Alaska. In the NW corner of Section 15, T.72S., R.87E., Copper River Meridian.

RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 38 to 42 degrees F. The histic epipedon ranges from 8 to 14 inches in thickness and includes part of the A horizon in some pedons. The depth to bedrock ranges from 10 to 14 inches. The mean summer soil temperature is about 46 degrees F.

The A horizon has hue ranging from 10YR through 2.5Y, value moist from 2 through 6 and chroma moist from 0 through 3. Texture is dominantly silt loam, but ranges to include very fine sandy loam and loam. Mottles are present in some pedons. Gravel content ranges from 0 to 15 percent.

A Bw horizon is present in some pedons and has a hue of 10YR through 5YR, value from 2 to 4 and chroma from 1 to 4. Coarse fragment content ranges from 10 to 30 percent, with 5 to 30 percent gravel and 0 to 10 percent cobble. Texture is commonly silt loam or sandy loam. Mottles are present ion some pedons.

The C horizon has hue from 5YR through 2.5Y, value moist from 2 through 5, and chroma moist from 0 through 4. The hue of the mottles ranges from 2.5YR through 5Y, value moist from 2 through 7, and chroma moist from 1 to 8. Texture is commonly silt loam, but ranges to include fine sandy loam, sandy loam, and very fine sandy loam. Gravel content ranges from 0 to 35 percent.

COMPETING SERIES: There are no competing series in the same family.

GEOGRAPHIC SETTING: The Helm soils are on backslopes and benches of hills and mountains. Helm soils are formed in residuum and colluvium from phyllite, schist, sedimentary or granitic bedrocks. They are underlain by bedrock within 20 inches. The climate is humid maritime with mean annual precipitation of 120 inches. The mean annual temperature is 46 degrees F. Slopes range from 5 to 120 percent.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hydaburg, Kaikli, Kina, and Sunnyhay soils. Hydaburg and Sunnyhay soils are alpine organic soils on ridges and shoulder slopes. Kaikli and Kina soils are organic soils on structural benches on hillsides and in valley bottoms.

DRAINAGE AND PERMEABILITY: Poorly drained. Moderately rapid permeability in the organic matter and moderate in the mineral horizons. Runoff is slow to rapid. The water table is within 10 inches of the organic surface.

USE AND VEGETATION: Used for watershed protection, wildlife habitat, and recreation. The overstory vegetation is predominantly western hemlock and western redcedar , with lesser amounts of Sitka spruce and Alaska-cedar. The understory is mostly blueberry species, rusty menziesia, devilsclub, yellow skunkcabbage, and mosses.

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

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

SERIES ESTABLISHED: Ketchikan Area, Alaska, 1994.

REMARKS: Diagnostic horizons and features recognized in this pedon include: a histic epipedon from 8 to 0 inches; cryic temperature regime; a lithic contact at 10 inches; pH less than 5.0 (0.01M CaCl2) from 0 to 10 inches; loamy particle size from 0 to 10 inches.

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National Cooperative Soil Survey
U.S.A.