LOCATION MENDELTNA AK
Established Series
Rev. MHC/JPM
05/2022
MENDELTNA SERIES
The Mendeltna series consists of very poorly and poorly drained soils formed in a thick organic mat over lacustrine nearshore deposits. Permafrost occurs at a depth of 14 to 29 inches below the mineral soil surface. Mendeltna soils are on broad high lacustrine terraces. Slopes range from 0 to 7 percent. Mean annual temperature is about 26 degrees F. and the average annual precipitation is about 12 inches.
TAXONOMIC CLASS: Loamy, mixed, superactive, nonacid, subgelic Typic Historthels
TYPICAL PEDON: Mendeltna peat on a 2 percent slope under black spruce forest at 1600 feet elevation. (When described the soil was wet)
Oi--9 inches to 4 inches; dark reddish brown (5YR 3/2) peat consisting of raw fibrous moss and root fibers; clear wavy boundary. (4 to 8 inches thick)
Oe--4 inches to 0; black (5YR 2.5/1) mucky peat; partially decomposed moss and root fibers; abrupt smooth boundary. (3 to 7 inches thick)
A--0 to 2 inches; very dark grayish brown (10YR 3/2) mucky silt loam; weak fine subangular blocky structure; very friable, slightly sticky, slightly plastic; many very fine, fine and medium roots; neutral (pH 7.0); abrupt smooth boundary. (1 to 5 inches thick)
2C--2 to 16 inches; olive gray (5Y 4/2) gravelly clay loam; massive; firm, sticky and plastic; 25 percent gravel and 5 percent cobble; few very fine and fine roots; slightly alkaline (pH 7.4); abrupt smooth boundary. (14 to 22 inches thick)
2Cf--16 to 26 inches; olive gray (5Y 4/2) gravelly clay loam; slightly alkaline (pH 7.8); 25 percent subangular gravel; weakly effervescent; disseminated lime; frozen on August 23, 1983.
TYPE LOCATION: Copper River Area, Alaska; 10 miles west of Glennallen, 800 feet north and 1200 feet east of the SW corner of section 18, T. 4N., R. 3W., Copper River Meridian.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is less than 32 degrees F. The mat of organic material consists of fibrous peat over partially decomposed moss, twigs, and root fibers 8 to 14 inches thick. Depth to permafrost ranges from 14 to 29 inches below the surface of the mineral soil two months after the summer solstice. Texture of the control section includes loam, clay loam, and silty clay loam. There is more than 18 percent clay and more than 15 percent fine sand or coarser. Coarse fragment content ranges from 0 to 30 percent and includes subangular pebbles and cobbles. Reaction throughout the mineral profile is neutral to moderately alkaline.
The A horizon has moist hue of 7.5YR or 10YR; moist value of 2 or 3; and moist chroma of 1, 2, or 3. Color striations are common due to variable organic matter content. Texture is mucky silt loam, silt loam or silt.
The 2C horizon has moist hue of 10YR, 2.5Y, or 5Y; moist value of 4 or 5; and moist chroma of 1 or 2. Mottles have moist hue of 7.5YR, 10YR, or 5GY; mottles are absent in many profiles. Texture is loam, clay loam, or silty clay loam. Coarse fragment content ranges from 5 to 30 percent subangular gravel and cobble. A lag concentrate of coarse fragments is common along the surface of the horizon.
The 2Cf horizon has moist hue of 10YR, 2.5Y, or 5Y; moist value of 4 or 5; and moist chroma of 1 or 2. Textures include loam, clay loam, and silty clay loam. Clay content often increases with depth. Coarse fragment content ranges from 5 to 30 percent and includes subangular gravel and cobble. Effervescence is slight or none with cold dilute HCl.
COMPETING SERIES: These are the
Copper River, Deborah (T),
Kuslina,
Saulich,
Tolsona, and
Umiat (T) soils. Copper River, Deborah, Kuslina, Saulich, and Tolsona soils have less than 18 percent clay. Umiat soils have weathered bedrock within the control section.
GEOGRAPHIC SETTING: Mendeltna soils formed in a thick organic mat over lacustrine nearshore deposits. They are on level to gently sloping lacustrine terraces.
The climate is subarctic continental with long, cold winters and short, warm summers. Mean annual precipitation ranges from 8 to 17 inches and the mean annual snowfall is 39 to 68 inches. Mean January temperature is minus 10 degrees F., mean July temperature is 56 degrees F., and the mean annual temperature varies from 23 to 27 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Klawasi,
Tebay, and
Tolsona soils. Klawasi soils are on lower level lacustrine terraces and have clayey particle size. Tebay soils are on glacial moraines and drumlins, have cambic horizons, and are well drained. Tolsona soils are on higher elevation glacial till plains and have sandy loam textures.
DRAINAGE AND PERMEABILITY: Very poorly and poorly drained. Runoff is very slow. Permeability is moderately rapid in the organic mat and moderate in the mineral soil. The profile is saturated and free water occurs above the permafrost. Altered drainage occurs where the insulating organic mat is destroyed by fire or clearing. Loss of the organic mat results in lowering of the permafrost level and subsequent lowering of the water table.
USE AND VEGETATION: Mendeltna soils support native vegetation of black spruce and willows. The successional state of the vegetation in a given area is closely related to the fire history. This soil is used primarily for wildlife habitat.
DISTRIBUTION AND EXTENT: Copper River Basin, Alaska. The series is extensive.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Copper River Area, Alaska. 1986.
REMARKS: Diagnostic horizons and features recognized in this pedon are a histic epipedon from 9 to 0 inches, permafrost at 16 inches, and saturated conditions above the permafrost; pH greater than 5.5 (1:1,H2O); loamy particle size class from 10 to 26 inches.
Mendeltna is the permafrost counterpart of the Chetaslina series. The Chetaslina series represents soils where where the permafrost and water table have dropped below the series control section due to disturbance of the organic mat.
National Cooperative Soil Survey
U.S.A.