LOCATION SNETTISHAM              AK

Established Series
Rev.CSC/JMD/JPM
12/2022

SNETTISHAM SERIES

The Snettisham series consists of shallow to bedrock, somewhat poorly drained soils formed in colluvium and residuum from phyllite and schist on hillslopes and mountainslopes. Slopes range from 35 to 55 percent. Mean annual precipitation is in excess of 60 inches and the mean annual temperature is about 46 degrees F.

TAXONOMIC CLASS: Loamy, mixed, superactive Lithic Humicryods

TYPICAL PEDON: Snettisham sandy loam - on a southwest facing broken slope of 55 percent at 1480 feet elevation under conifer forest vegetation. (All colors are for moist soil)

Oi -- 6 to 3 inches; forest litter and living mosses; many fine, medium and coarse roots; clear smooth boundary.

Oa -- 3 to 0 inches; muck; many fine, medium and coarse roots; clear smooth boundary.

E -- 0 to 2 inches; very dark gray (10YR 3/1) sandy loam; weak fine subangular blocky structure; very friable; few fine and medium roots; 5 percent gravel; clear smooth boundary. (1 to 4 inches thick)

Bh -- 2 to 6 inches; black (5YR 2.5/1) mucky sandy loam; weak medium subangular blocky structure; very friable; few fine and medium roots; 10 percent channers; gradual smooth boundary. (0 to 4 inches thick)

Bhs -- 6 to 12 inches; very dark grayish brown (10YR 3/2) channery sandy loam; weak medium subangular blocky structure; very friable; few fine faint very dark gray (10YR 3/1) mottles; few fine roots; 15 percent channers; gradual smooth boundary. (1 to 6 inches thick)

C -- 12 to 14 inches; very dark grayish brown (2.5Y 3/2) very channery sandy loam; massive; 70 percent channers; gradual smooth boundary. (0 to 4 inches thick)

R -- 14 inches; consolidated schist bedrock

TYPE LOCATION: Hawk Inlet, Chatham Area, Alaska. NW1/4, SE1/4, Sec. 8, T.43S., R.56E., Copper River Meridian.

RANGE IN CHARACTERISTICS: MAST ranges from 38 to 42 degrees F. The thickness of the solum ranges from 2 to 14 inches. Depth to bedrock ranges from 10 to 14 inches. Reactions increase with depth, ranging from extremely acid to slightly acid. Coarse fragment content in the control section ranges from 0 to 30 percent schist channers. Colluvial activity has resulted in the formation of buried horizons in many profiles.

Combined thickness of the O horizons range from 2 to 8 inches. The E horizon has hue of 7.5YR or 10YR, value from 3 to 6 and chroma from 1 to 4. Texture is sandy loam or silt loam. Coarse fragment content ranges from 0 to 10 percent channers.

The Bhs horizon has hue from 5YR to 10YR, value and chroma of 2 or 3. Texture is sandy loam or silt loam. Coarse fragment content ranges from 0 to 15 percent channers. Prominent or distinct mottles are commonly present in the lower part of the horizon.

A mottled Bs and/or C horizon are present in some pedons. When present, the C horizon has greater than 35 percent coarse fragments.

COMPETING SERIES: These are the Sarkar (AK) and Traitors (AK) series in the same family. Sarkar and Traitors soils lack mottles in the spodic horizons.

GEOGRAPHIC SETTING: The Snettisham soils are on hillslopes and mountain slopes. The parent material is colluvium and residuum from phyllite and schist rocks underlain by phyllite and schist. The climate is humid maritime with a mean annual precipitation range of 60 to 220 inches. The mean annual temperature is about 46 degrees F. and the mean summer temperature is about 57 degrees F. Elevation ranges from 0 to 1500 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Passage, Fordsterror, and Kaikli soils on similar landforms. Passage soils are well drained and greater than 20 inches to bedrock. Fordsterror soils are greater than 40 inches to bedrock. Kaikli soils are very poorly drained organic soils.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Moderate permeability. Runoff is very slow.

USE AND VEGETATION: The Snettisham soils are used for timber production, watershed protection, wildlife habitat and recreation. The overstory is dominantly western hemlock. The understory is dominantly blueberry with some skunk cabbage.

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

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

SERIES ESTABLISHED: Chatham Area, Alaska, Tongass National Forest, 1992.

REMARKS: Diagnostic horizons and features recognized in this soil are: a. albic horizon from 0 to 2 inches; spodic horizons from 2 to 6 inches with assumed organic carbon content greater than 6 percent in the upper 4 inches; cryic temperature regime; a lithic contact at 14 inches; weighted average particle size of loamy from 0 to 14 inches.

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National Cooperative Soil Survey
U.S.A.