LOCATION HEWITT             AK
Established Series
KMO-JPM
11/2002

HEWITT SERIES


The Hewitt series consists of very deep, very poorly drained organic soils formed in soft peat materials derived from sedges and moss overlying silty alluvium. Hewitt soils are in muskegs on floodplains. Slopes range from 0 to 3 percent. The mean annual temperature is about 32 degrees F. and the average annual precipitation is about 25 inches.

TAXONOMIC CLASS: Loamy, mixed, euic Terric Cryohemists

TYPICAL PEDON: Hewitt peat -- on a 1 percent slope under bog vegetation. (All colors are for moist soil)

Oi--0 to 4 inches; dark yellowish brown (10YR 4/4) slightly decomposed peat; yellowish brown (10YR 5/6) squeezed; many dark brown (10YR 3/3) patches; about 80 percent fiber, 60 percent rubbed; many roots; dominantly moss peat with sedge peat; slightly acid; clear smooth boundary. (2 to 8 inches thick)

Oe--4 to 7 inches; dark brown (10YR 3/3) moderately decomposed peat; about 50 percent fiber, 30 percent rubbed; common roots; dominantly moss peat; neutral; abrupt smooth boundary. (0 to 8 inches thick)

C--7 to 12 inches-- dark greenish gray (5GY 4/1) silty clay loam; massive; firm; slightly sticky, slightly plastic; thin layer of dark brown peat about 1 inch thick with less than 30 percent fiber; few roots; neutral; abrupt smooth boundary. (0 to 5 inches thick)

O'e1--12 to 27 inches; very dark grayish brown (10YR 3/2) peat; about 50 percent fiber, 25 percent rubbed; derived mainly from sedges and moss; few roots; neutral; abrupt smooth boundary. (10 to 20 inches thick)

O'e2--27 to 33 inches; very dark grayish brown (10YR 3/2) peat; about 50 percent fiber, 25 percent rubbed; derived mainly from sedges and roots; approximately 30 percent strata of 1/2 to 1 inch thick dark greenish gray (5GY 4/1) silt loam; massive; nonsticky and nonplastic; neutral; abrupt smooth boundary. (5 to 20 inches thick)

C'--33 to 60 inches; dark gray (5Y 4/1) silt loam; massive; firm, nonsticky and nonplastic; few thin discontinuous strata of brown peat.

TYPE LOCATION: Yentna Area, Alaska; in the SW quarter of the NW quarter of section 25, T.22N., R.11W., Seward Meridian.

RANGE IN CHARACTERISTICS: Depth to the continuous underlying mineral material ranges from 25 to 50 inches. Strata of mineral material up to 5 inches thick can occur throughout the peat materials. The mineral strata are commonly silt loam or silty clay loam. The mineral strata are present on the surface in some pedons. Reaction throughout the profile ranges from neutral to strongly acid. The pH (0.01M CaCl2) of the organic material is 4.5 or greater within some part of the controlsection.

The organic materials have hue from 5YR to 10YR; value moist of 2 or 3; and chroma moist from 1 to 4. Up to 10 percent coarse woody fragments may be present in the subsurface tier of some pedons.

The mineral strata and the continuous underlying mineral material is massive, firm, silt loam or silty clay loam with 20 to 35 percent clay.

COMPETING SERIES: These are the Doroshin, Tacoosh and Tepete series in the same family. Doroshin soils have less than 10 percent clay in the mineral substratum. Tacoosh soils are calcareous in the underlying mineral material within the control section. Tepete soils have continuous loose sand and gravel in the lower part of the control section.

GEOGRAPHIC SETTING: Hewitt soils are in muskegs on floodplains. Slopes range from 0 to 3 percent. Hewitt soils formed in decomposing peat overlying silty alluvium. The mean annual temperature ranges from 30 to 40 degrees F. The average annual precipitation ranges from 20 to 30 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Killey, Moose River, and Wasilla soils. These are all mineral soils on floodplains.

DRAINAGE AND PERMEABILITY: Very poorly drained. Water table at or near the surface. Rapid permeability in the organic materials and slow permeability in the underlying mineral material. Subject to flooding. Ponded to slow runoff.

USE AND VEGETATION: The native vegetation is mainly mosses and sedges with scattered bog birch and ericaceous shrubs. Used as wildlife habitat.

DISTRIBUTION AND EXTENT: Southcentral Alaska. The series is of minor extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Yentna Area, Alaska, 1986.

REMARKS: Diagnostic horizons and features recognized in this profile include: dominantly hemic material from 4 to 33 inches; mineral material from 33 to 0 inches; frigid temperature regime; pH (0.01M CaCl2) greater than 4.5 in part of the control section; loamy particle size from 33 to 60 inches.


National Cooperative Soil Survey
U.S.A.