LOCATION MENTASTA                AK

Established Series
SDB
08/2025

MENTASTA SERIES

Depth class: very deep
Drainage class: well drained
Parent material: silty loess over sandy and gravelly till
Landscape: mountains
Landform: hillslopes
Slope: 5 to 50 percent
Mean annual precipitation: about 600 mm (24 in)
Mean annual air temperature: about -3 degrees C (27 degrees F)
Frost-free period: 36 to 71 days

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid Typic Cryorthents

TYPICAL PEDON: Mentasta stony silt loam in a white spruce and resin birch community on a northeast facing linear, linear footslope with on a slope of 5 percent at an elevation of 1152m (3780 ft)

Oe--0 to 7 cm (0 to 3 in); moderately decomposed plant material, very dark brown (7.5YR 2.5/2) broken face moist; low excavation difficulty; common very fine and fine roots throughout; neutral (pH 7.0); clear smooth boundary (3 to 10 cm, 1 to 4 in)

A--7 to 12 cm (3 to 5 in); stony silt loam, black (10YR 2/1) broken face moist; moderate fine granular structure; soft, very friable, nonsticky, nonplastic; nonsmeary; common very fine and fine roots throughout; neutral (pH 6.7); clear wavy boundary (2 to 9 cm,1 to 4 in)

Bw--12 to 18 cm (5 to 7 in); silt loam, olive brown (2.5Y 4/3) broken face moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; nonsmeary; common very fine and fine roots throughout; neutral (pH 6.7); abrupt wavy boundary (4 to 8 cm, 2 to 3 in)

2C1--18 to 36 cm (7 to 14 in); extremely gravelly sandy loam, dark olive brown (2.5Y 3/3) broken face moist; massive; soft, very friable, nonsticky, nonplastic; nonsmeary; common very fine roots top of horizon; 66 percent subangular gravels by volume; neutral (pH 7.0); clear wavy boundary.

2C2--36 to 150 cm (14 to 59 in); extremely gravelly sandy loam, olive (5Y 4/3) broken face moist; massive; soft, very friable, nonsticky, nonplastic; nonsmeary; common very fine roots top of horizon; 66 percent subangular gravels by volume; neutral (pH 7.0). (123 to 141 cm, 48 to 56 in)

TYPE LOCATION: Valdez-Cordova Census Area County, Alaska; latitude 61.56446, longitude -144.52930, zone 6, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: 0 to 4 degrees C. (32 to 39 degrees F)
Thickness of organic material: 0 to 10 cm (0 to 4 in)
Thickness of ochric epipedon: 5 to 19 cm (2 to 7 in)
Depth to lithologic discontinuity: 9 to 27 cm (4 to 11 in)

Oi and Oe horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 3
Texture: slightly decomposed organic material, moderately decomposed organic material
Organic matter: 60 to 90 percent
Reaction class: slightly acid to slightly alkaline (pH 6.5 to 7.5)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 4
Chroma: 1 to 3
Texture: silt loam, stony silt loam
Sand: 20 to 35 percent
Silt: 56 to 74 percent
Clay: 6 to 12 percent
Organic matter: 2 to 7 percent
Reaction class: moderately acid to slightly alkaline (pH 6.0 to 7.5)

Bw horizon:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 3 to 4
Texture: silt loam, cobbly silt loam
Sand: 20 to 35 percent
Silt: 54 to 74 percent
Clay: 6 to 12 percent
Rock fragments: 15 to 25 percent cobbles
Organic matter: 1 to 5 percent
Reaction class: moderately acid to slightly alkaline (pH 6.0 to 7.5)

2C horizon:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 2 to 6
Texture: very gravelly sandy loam, extremely gravelly sandy loam
Sand: 55 to 70 percent
Silt: 18 to 35 percent
Clay: 10 to 15 percent
Rock fragments: 40 to 70 percent gravels
Organic matter: 0.5 to 1.5 percent
Reaction class: slightly acid to slightly alkaline (pH 6.5 to 7.7)

COMPETING SERIES: These are the Bracos (NM), Dagelet (AK), Enigma (AK), Gralic (NV), Ingik (AK), Jackmore (NV), Kaina (MT), and Mascot (AK) series.
Bracos, Dagelet and Enigma soils have a lithic contact between 50 and 150 cm.
Gralic soils lack a loess cap, and occur at elevations above 2285 m (7,500 ft)
Ingik and Mascot soils have a paralithic contact between 50 and 150 cm.
Jackmore soils occur in mountains at elevations above 2670m (8760 ft) and have a xeric moisture regime.
Kaina soils lack a loess cap and have a mean annual precipitation above 1000 mm (39 in).

GEOGRAPHIC SETTING:
Elevation: 800 to 1400 meters (2625 to 4595 ft)
Parent material: silty loess over sandy and gravelly till
Landform: hillslopes
Slopes: 5 to 50 percent
Mean annual precipitation: 400 to 800 mm (16 to 31 in)
Mean annual air temperature: -4 to -2 degrees C. (25 to 28 degrees F)
Frost-free period: 36 to 71 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bartell, Fields, Tasta, and Tsina series.
Bartell soils are poorly drained, have a histic epipedon, and occur on drainage ways and stream terraces.
Fields soils are well drained, have umbric epipedons, lithic contacts within 2 m (79 in) of the soil surface, and occur on mountains.
Tasta soils are well drained, have a mollic epipedon, and occur on mountain slopes above 800 m (2600 ft) elevation.
Tsina soils are well drained and occur on mountain slopes above 800 m (2600ft) elevation.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well
Saturated Hydraulic Conductivity: very high in the Oe horizon, moderately high in the A and Bw horizons, high in the 2C horizons.
Permeability: very rapid in the Oe horizon, moderate in the A and Bw horizons, moderately rapid in the 2C horizons.

Runoff: medium

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: white spruce and resin birch.

DISTRIBUTION AND EXTENT: MLRA 228 Interior Alaska mountains.
Extent: moderate

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Wasilla, Alaska

SERIES ESTABLISHED: North Copper River Soil Survey, Alaska, 2024.

REMARKS: Diagnostic features and horizons recognized in this profile include:

Particle-size control section: 32 to 107 cm (13 to 42 in)

Ochric epipedon: 0 to 12 cm (0 to 5 in) (Oe and A horizons)

Lithologic discontinuity: 18 to 150 cm (7 to 59 in) (2C horizon)

Abrupt textural change: 18 to 150 cm (7 to 59 in) (2C horizon)

ADDITIONAL DATA:

User pedon Id: 2022AK261557

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National Cooperative Soil Survey
U.S.A.