LOCATION MEDFRA                  AK

Inactive Series
Rev. DBS/SR
02/2022

MEDFRA SERIES

This classification is tentative (see Remarks). Typically, under a thick 0 horizon these soils have dark A1 horizons and olive brown to olive C horizons that are mottled with olive gray or gray. The soils are silty throughout and are perennially frozen at shallow depths.

TAXONOMIC CLASS:

TYPICAL PEDON: Medfra silt loam - forest (Colors are for moist conditions)

01--10 to 0 inches; Brown (7.5YR 4/4; 7.5YR 5/6, squeezed) partially decomposed moss; many roots; abrupt smooth boundary. (6 to 12 inches thick)

A1--0 to 2 1/2 inches; Very dark brown (10YR 2/2) silt loam; many streaks and patches of very dark gray (10YR 3/1), weak fine granular structure; very friable; many roots; clear wavy boundary. (2 to 5 inches thick)

C1--2 1/2 to 14 inches; Olive brown (2.5Y 4/4) silt loam; large patches of brown (10YR 4/3); common, medium, distinct olive gray (5Y 5/2) mottles; massive; nonsticky, nonplastic; few roots; abrupt smooth boundary. (8 to 15 inches thick)

C2f--14 to 21 inches; Olive (5Y 4/3) silt loam; common, medium faint gray (5Y 5/1) mottles; few streaks of olive brown (2.5YR 4/4); frozen August 13, 1967.

TYPE LOCATION: Medfra Area, Alaska. SW 1/4 SW 1/4, Sec. 23, T 27 5, R 21 E, Rateel River Meridian.

RANGE IN CHARACTERISTICS: Depth to permafrost ranges from 10 to 20 inches below the mineral surface. Matrix colors in the C horizons are in hues of 2.5Y and 5Y, values of 4 and 5, and chroma of 2 to 4. Large patches of slightly redder materials are common. Grayish mottles generally occur in the lower part of the profile but may also occur in the upper parts of the C horizon.

COMPETING SERIES: These include the Goldstream, Kuskokwim, Owhat and Saulich series of the same family. All have lower chromas. The Goldstream series are formed in silty sediments that are fairly high in mica. The Kuskokwim soils are commonly strongly mottled. The Owhat soils have thick dark Al horizons. The Saulich series are formed in nonacid silty materials that are fairly high in mica.

GEOGRAPHIC SETTING: The Medfra soils occur on nearly level to moderately steep slopes of rounded hills. The regolith consists of deep to moderately deep silty loess and colluvium over shattered bedrock. The silty material is perennially frozen below a depth of 20 inches. The climate is subarctic continental with long cold winters and short warm summers. Mean annual air temperature is about 26 degrees F, and mean annual precipitation is about 20 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Kuskokwim series, and the Telida and McGrath series. The Telida soils have thin 0 horizons and are not perennially frozen. The McGrath soils are well drained and have a spodic horizon.

DRAINAGE AND PERMEABILITY: Poorly drained. Permeability is moderate in the unfrozen material. Runoff is slow to moderate depending upon slope gradient.

USE AND VEGETATION: Used only by wildlife. The natural vegetation consists of black spruce, willow, and a thick ground cover of moss.

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

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

SERIES PROPOSED: Medfra Area, Alaska, 1967. (Source of name is the village of Medfra).

REMARKS: Under the present criteria chromas are too high for placement in the Aquepts but, because of the histic epipedon, no other classification is possible.

OSED scanned by SSQA. Last revised by state on 04/69.

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National Cooperative Soil Survey
U.S.A.