LOCATION MAHLORIVER AK

Established Series
SDB
08/2025

MAHLORIVER SERIES

Depth class: very deep
Drainage class: well drained
Parent material: mossy organic material over sandy and gravelly till over sandy slope alluvium
Landscape: mountains
Landform: kames and glacial-valley floors
Slope: 8 to 40 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 120 days

TAXONOMIC CLASS: Sandy, mixed Typic Haplocryepts

TYPICAL PEDON: Mahloriver loam in a bog labrador tea and moss community on a north facing linear, convex backslope on a slope of 33 percent at an elevation of 738m (2420 ft)

Oi--0 to 7 cm (0 to 3 in); slightly decomposed plant material, dark brown (10YR 3/3) moist; many very fine, many fine, few medium, and many coarse roots throughout; strongly acid (pH 5.5); clear wavy boundary

Oe--7 to 15 cm (3 to 6 in); moderately decomposed plant material, black (10YR 2/1) moist; many very fine, many fine, few medium, and many coarse roots throughout; strongly acid (pH 5.2); abrupt wavy boundary

A--15 to 21 cm (6 to 8 in); loam, very dark gray (2.5Y 3/1) moist; moderate fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; nonsmeary; many very fine, few fine, common medium, and many coarse roots throughout; many very fine and many fine dendritic tubular pores; strongly acid (pH 5.3); abrupt wavy boundary

Bw--21 to 29 cm (8 to 11 in); gravelly sandy loam, dark yellowish brown (10YR 3/4) moist; weak medium subangular blocky structure; loose, very friable, nonsticky, nonplastic; nonsmeary; many very fine, fine, and coarse, and few medium roots throughout; very fine dendritic tubular and fine dendritic tubular pores; 19 percent subrounded gravel by volume; moderately acid (pH 5.7); clear wavy boundary.

2BC--29 to 44 cm (11 to 17 in); loamy sand, dark olive brown (2.5Y 3/3) moist; massive; slightly hard, friable, nonsticky, nonplastic; nonsmeary; common very fine roots throughout; interstitial pores; moderately acid (pH 5.9); gradual wavy boundary

2C1--44 to 62 cm (17 to 24 in); sand, black (5Y 2.5/2) moist; single grain; loose, nonsticky, nonplastic; nonsmeary; interstitial pores; moderately acid (pH 5.9); clear wavy boundary

2C2--62 to 205 cm (24 to 81 in); sand, black (5Y 2.5/1) moist; single grain; loose, nonsticky, nonplastic; nonsmeary; interstitial pores; moderately acid (pH 6.0).

TYPE LOCATION: Valdez-Cordova Census Area County, Alaska; latitude 62.72511, longitude -143.89866, UTM 6958294.42 north and UTM 351833.40 east, zone 7, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: -1 to 5 degrees C. (30 to 41 degrees F)
Thickness of organic material: 11 to 17 cm (4 to 7 in)
Thickness of folistic epipedon: 15 to 17 cm (6 to 7 in)
Thickness of cambic horizon (if present): 15 to 30 cm (6 to 12 in)
Depth to lithologic discontinuity: 33 to 55 cm (13 to 22 in)

Oi, Oe, and Oa horizons:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 3
Texture: slightly decomposed organic material, moderately decomposed organic material, and highly decomposed organic material.
Organic matter: 60 to 90 percent
Reaction class: very strongly acid to slightly acid (pH 4.5 to 6.5)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 2
Texture: loam
Sand: 39 to 52 percent
Silt: 36 to 49 percent
Clay: 9 to 12 percent
Rock fragments: 0 percent
Organic matter: 4 to 7 percent
Reaction class: very strongly acid to moderately acid (pH 4.5 to 6.0)

Bw, 2BC horizons:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 2 to 4
Texture: sandy loam, gravelly sandy loam, loamy sand
Sand: 50 to 85 percent
Silt: 7 to 40 percent
Clay: 1 to 12 percent
Rock fragments: 0 to 25 percent
Gravels: 0 to 25 percent
Organic matter: 1 to 4 percent
Reaction class: very strongly acid to neutral (pH 5.0 to 6.8)

2C1, 2C2 horizons:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 1 to 3
Texture: sand
Sand: 90 to 98 percent
Silt: 0 to 9 percent
Clay: 1 to 3 percent
Rock fragments: 0 percent
Organic matter: 0.5 to 1 percent
Reaction class: strongly acid to neutral (pH 5.5 to 6.8)

COMPETING SERIES: These are the Beales, Chistna, Chistochina, Dureile, Gustavus, and Kismetpeak soils.
Kismetpeak soils are somewhat excessively drained, have less than 15 percent coarse fragments in the mineral horizons, and lack a folistic epipedon.
Beals soils are somewhat excessively drained, do not have coarse fragments in the parent material, and occur on sandy hills and sandy plains.
Chistna soils are somewhat excessively drained, have a thin cambic horizon, and occur on glacial outwash
Chistochina soils are somewhat excessively drained, has a silt loam surface texture, and darker colored parent material.
Dureile soils are well drained, a thin A horizon, and occur on outwash plains.
Gustavus soils are well drained, lack an A horizon, and occur on outwash deltas from 0 to 50 m in elevation.

GEOGRAPHIC SETTING:
Elevation: 600 to 1000 meters (1970 to 3280 ft)
Parent material: mossy organic material over sandy and gravelly till over sandy slope alluvium
Landform: kames and glacial-valley floors
Slopes: 8 to 40 percent
Mean annual precipitation: 400 to 800 mm (24 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 Dodger, Ellisgap, Greylingcreek, Slatka, Tisa, and Tok soils.
Dodger soils are poorly drained, they are organic soils, have permafrost, and occur on outwash terraces on mountains.
Ellisgap soils are poorly drained permafrost soil, have histic epipedons, cryoturbation starting between 14 and 27 cm (6 to 11 in) deep, and occur in river valleys and terraces.
Greylingcreek soils are excessively drained and occur in mountain valleys and moraines.
Slatka soils are somewhat poorly drained, have permafrost, histic epipedons, cryoturbation, and occur on mountain slopes.
Tisa soils are somewhat excessively drained, have mollic epipedons, and occur on mountain terraces.
Tok soils are well drained, a fine sandy loam cambic horizon over gravelly till, and occur on kames and glacial valley floors.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well
Saturated Hydraulic Conductivity: Very high in the Oi, Oe, BC and 2C horizons, high in the A and Bw horizons
Permeability: very rapid in the Oi, Oe, BC and 2C horizons, moderate in the A and Bw horizons
Runoff: medium

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: bog labrador tea, moss 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: 40 to 115 cm (16 to 45 in)

Folistic epipedon: 0 to 15 cm (0 to 6 in) (Oi and Oe horizon)

Lithologic discontinuity: 44 to 200 cm (17 to 79 in) (2C horizon)

ADDITIONAL DATA:

User pedon Id: 2023AK261504

National Cooperative Soil Survey
U.S.A.