LOCATION CHILKOOT                AK

Established Series
Rev. EJK/JPM
02/2022

CHILKOOT SERIES

The Chilkoot series consists of very deep, poorly and somewhat poorly drained soils that formed in sandy alluvium. Chilkoot soils are on floodplains and low stream terraces. Slopes range from 0 to 5 percent. Mean annual temperature is about 43 degrees F., and the average annual precipitation is about 80 inches.

TAXONOMIC CLASS: Sandy, mixed Typic Cryaquents

TYPICAL PEDON: Chilkoot silt - on a nearly level floodplain at 50 feet elevation under forest vegetation. (All colors are for moist soil unless otherwise stated).

Oi--3 inches to 0; partially decomposed twigs, leaves, and moss; abrupt smooth boundary. (1 to 5 inches thick)

A--0 to 5 inches; olive gray (5Y 5/2) silt; weak fine subangular blocky structure; very friable; nonsticky and nonplastic; many very fine, fine, medium, and coarse roots; slightly acid (pH 5.2); abrupt smooth boundary. (1 to 6 inches thick)

C1--5 to 60 inches; light olive gray (5Y 5/2) and dark gray (10YR 4/1) loamy fine sand; single grain; loose; nonsticky and nonplastic; common fine and medium roots decreasing to few fine roots with depth; water table at 18 inches (5/23/83); moderately acid (pH 6.0).

TYPE LOCATION: Haines Area, Alaska; NE 1/4, NE 1/4, Section 9, T.29S., R.59E., Copper River Meridian.

RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 38 to 42 degrees F. Textures in the 10 to 40 inch control section include sand, very fine sand, fine sand, loamy sand, loamy fine sand, and loamy very fine sand. Textures are often stratified. Coarse fragment content in the control section ranges from 0 to 20 percent. The water table fluctuates between 0 and 20 inches but is normally within 10 inches of the surface. In some profiles the watertable has dropped below 20 inches due to altered drainage. Reaction throughout the profile ranges from very strongly acid to slightly acid.

The A horizon, when present, has hue of 5Y, 2.5Y, 10YR, or 7.5YR, value from 2 through 5 moist, and chroma from 0 through 3 moist. Texture is silt, silt loam, very fine sandy loam, or fine sandy loam. Coarse fragment content ranges from 0 to 10 percent with 0 to 10 percent gravel and 0 to 5 percent cobble.

The C horizons have hue of 5Y, 2.5Y, 10YR, or 7.5YR; value from 3 through 6 moist, and chroma from 1 through 4 moist. Some colors are due to uncoated grains of sand. Mottles are commonly present, however, where absent, the matrix chroma is 1 or less. Texture is sand, fine sand, loamy sand or loamy fine sand, with occasional thin strata of very fine sandy loam or silt loam. Coarse fragment content ranges from 0 to 20 percent, with 0 to 20 percent gravel and 0 to 5 percent cobble.

COMPETING SERIES: This is the Ashmun series. Ashmun soils are calcareous and are neutral to moderately alkaline in the control section.

GEOGRAPHIC SETTING: The Chilkoot soils occur on floodplains and and low stream terraces and are formed in alluvium. The climate is humid maritime with the average annual precipitation ranging from 55 to over 200 inches. Mean annual temperature ranges from 40 to 45 degrees F. Slopes range from 0 to 5 percent. Elevations range from sea level to 800 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Funter, Kupreanof, Kushneahin, Lutak, Mosman, and Nataga soils. Funter and Kushneahin soils are organic soils in depressional areas. Kupreanof and Mosman soils are well drained soils on adjacent mountainslopes. Lutak soils are also well drained and are on adjacent alluvial terraces and moraines. Nataga soils occur on alluvial fans and are shallow over extremely gravelly sands.

DRAINAGE AND PERMEABILITY: Somehwat poorly drained and poorly drained; moderately rapid to rapid permeability; slow runoff; subject to frequent flooding. Depth to water table ranges from 0 to 20 inches but has dropped in some profiles due to altered drainage.

USE AND VEGETATION: The Chilkoot soils are used for wildlife habitat, recreation, and timber production. Native vegetation is dominantly cottonwood and Sitka spruce with an understory of alder, horsetail, devil's club, salmonberry, and mosses.

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

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

SERIES ESTABLISHED: Haines Area, Alaska. 1985

REMARKS: Diagnostic horizons and features recognized in this soil include: lack of a diagnostic subsurface horizon; mottling and matrix chromas less than 2 within 20 inches of the surface; weighted average particle size of sandy from 10 to 40 inches.

---

National Cooperative Soil Survey
U.S.A.