LOCATION DIAMONDCREEK            AK

Established Series
MPS
04/2026

DIAMONDCREEK SERIES

Depth class: very deep
Drainage class: poorly drained
Parent material: loess over loamy colluvium derived from sandstone
Landscape: hills
Landform: swales on hillslopes
Slopes: 10 to 35 percent
Mean annual precipitation: about 400 mm (15.7 in)
Mean annual air temperature: about -3 degrees C. (27 degrees F.)
Frost-free period: 75 to 90 days

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, acid, subgelic Humic Gelaquepts

TYPICAL PEDON: Diamondcreek highly organic silt loam in a white spruce woodland with a willow understory community on a west facing convex, linear backslope on a slope of 15 percent at an elevation of 333m (1093 ft)

Oi--0 to 2 cm (0 to 1 in); slightly decomposed plant material; very dark brown (7.5YR 2.5/2) broken face moist, brown (7.5YR 4/2) broken face dry; many very fine, fine, coarse and common medium roots throughout; very strongly acid (pH 4.5); abrupt smooth boundary. (1 to 10 cm, 0.5 to 4 in thick)

A--2 to 20 cm (1 to 8 in); highly organic silt loam; very dark brown (10YR 2/2) broken face moist, dark grayish brown (10YR 4/2) broken face dry; weak fine granular structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; many very fine, fine, and common medium roots throughout; common fine dendritic tubular pores; 5 percent gravel; noneffervescent; very strongly acid (pH 4.5); very abrupt smooth boundary. (18 to 34 cm, 8 to 14 in thick)

2Bg--20 to 54 cm (8 to 21 in); gravelly silt loam; grayish brown (2.5Y 5/2) broken face moist; light gray (2.5Y 7/2) broken face dry; moderate coarse subangular blocky structure; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; very few fine roots throughout; common very fine dendritic tubular pores; 5 percent medium prominent irregular moderately coherent strong brown strong brown (7.5YR 4/6), moist, iron-manganese nodules between peds and 15 percent fine prominent irregular brown (7.5YR 4/4), moist, masses of oxidized iron between peds; 20 percent gravel; noneffervescent; very strongly acid (pH 5.0); clear smooth boundary. (15 to 50 cm, 6 to 20 in thick)

2Cg--54 to 200 cm (21 to 79 in); gravelly loam; dark grayish brown (2.5Y 4/2) broken face moist, light brownish gray (2.5Y 6/2) broken face dry; massive; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; few very fine dendritic tubular pores; 5 percent medium prominent irregular moderately coherent strong brown (7.5YR 4/6), moist, iron-manganese nodules in matrix; 25 percent gravel; noneffervescent; strongly acid (pH 5.2).

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64.3518055, longitude -159.9402500, datum WGS84, UTM north 7136553.61 and UTM east 454590.71, zone 4, datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: aquic
Soil temperature regime: gelic
Mean annual soil temperature: -1 to 0 degrees C. (30 to 32 degrees F.)
Thickness of organic material: 1 to 10 cm (0.5 to 4 in)
Thickness of umbric epipedon: 18 to 34 cm (7 to 13 in)
Thickness of cambic horizon: 15 to 50 cm (6 to 20 in)
Depth to redoximorphic concentrations: 19 to 44 cm (8 to 17 in)
Depth to reduced matrix: 19 to 44 cm (8 to 17 in)

Oi horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 or 2
Texture: slightly decomposed material
Organic matter: 60 to 90 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

A horizon:
Hue: 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 3
Texture: highly organic silt loam, or its gravelly analogue
Sand: 10 to 48 percent
Silt: 50 to 80 percent
Clay: 2 to 10 percent
Rock fragments: 0 to 20 percent
Organic matter: 10 to 19 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

2Bg horizon:
Hue: 10YR, 2.5Y, 5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 1 or 2
Texture: silt loam, sandy loam or their gravelly analogues
Sand: 15 to 65 percent
Silt: 23 to 80 percent
Clay: 2 to 12 percent
Rock fragments: 0 to 25 percent
Organic matter: 1 to 4 percent
Reaction class: very strongly acid to strongly acid (pH 4.5 to 5.4)

2Cg horizon:
Hue: 10YR, 2.5Y, 5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 1 or 2
Texture: silt loam, fine sandy loam or their gravelly analogues
Sand: 40 to 70 percent
Silt: 20 to 50 percent
Clay: 2 to 10 percent
Rock fragments: 0 to 34 percent
Organic matter: 0.5 to 3 percent
Reaction class: very strongly acid to strongly acid (pH 4.5 to 5.4)

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 125 to 400 meters (410 to 1313 feet)
Parent material: loess over loamy colluvium derived from sandstone
Landform: swales on hillslopes
Slopes: 10 to 35 percent
Mean annual precipitation: 400 to 500 mm (16 to 20 in)
Mean annual air temperature: -5 to -1 degrees C. (23 to 30 degrees F.)
Frost free period: 75 to 90 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Agitchuk, Buck, Iyyagrik, Kanik, Kiuriruk, Niakuk, Tuttu, and Uniat soils.
Agitchuk soils have a histic epipedon, have cryoturbation, and occur on toeslopes and mountainbases
Buck soils have a paralithic contact at depths between 100 to 150 cm (40 to 60 in), lack aquic conditions, have andic soil properties, have cryoturbation, have spodic materials, lack a cambic horizon, have a loamy-skeletal particle size class, have a cryic soil temperature regime, and occur on low ridges
Iyyagrik soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), lack aquic conditions, have a mollic epipedon, lack a cambic horizon, have a loamy-skeletal particle size class, have a cryic soil temperature regime, and occur on mountainflanks, upper third
Kanik soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), have a fragmental layer starting at depths between 66 to 100 cm (26 to 39 in), lack aquic conditions, have an ochric epipedon, have a loamy-skeletal particle size class, have a nonacid reaction class, and occur on mountainflanks, upper and center thirds
Kiuriruk soils have permafrost, have a histic epipedon, lack a cambic horizon, have a coarse-silty particle size class, have a nonacid reaction class, and occur on terraces
Niakuk soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), have a fragmental layer starting at depths between 20 to 73 cm (8 to 29 in), lack aquic conditions, have an ochric epipedon, have a coarse-loamy over fragmental particle size class, have a cryic soil temperature regime, and occur on mountainflanks, upper and center thirds
Tuttu soils lack aquic conditions, have andic soil properties, lack a cambic horizon, and occur on footslopes, backslopes, and mountainflanks, lower third
Uniat soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), have a fragmental layer starting at depths between 10 to 91 cm (4 to 36 in), lack aquic conditions, have an ochric epipedon, have a fragmental particle size class, have a cryic soil temperature regime, and occur on mounds in valleys, mountaintops, and mountainflanks, upper third

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: poorly drained
Saturation during normal years: saturated between 0 and 25 cm (0 and 10 in) during the growing season
Saturated Hydraulic Conductivity: very high in the Oi horizon and moderately high to high in the A, 2Bg, and 2Cg horizons
Permeability: rapid to very rapid in the Oi horizon, moderate to moderately rapid in the A horizon, and moderate to rapid in the 2Bg and 2Cg horizons
Runoff: very high

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: tealeaf willow, bog blueberry, Schreber's big red stem moss, Richardson's willow, black crowberry, splendid feather moss, white spruce, knights plume moss, marsh Labrador tea, dwarf birch, polytrichum moss, sphagnum, lingonberry, red fruit bearberry, cup lichen, shrubby cinquefoil, arctic sweet coltsfoot, arctic kidney lichen

DISTRIBUTION AND EXTENT: MLRA 240, Nulato Hills-Southern Seward Peninsula Highlands. The series is of small extent.

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

SERIES ESTABLISHED: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey, Alaska, 2024.

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

Particle-size control section: 29 to 104 cm (11 to 41 in)

Umbric epipedon: 2 to 20 cm (1 to 8 in) (A horizon)

Cambic horizon: 20 to 54 cm (8 to 21 in) (2Bg horizon)

Lithologic discontinuity: 20 to 200 cm (8 to 79 in) (2Bg and 2Cg horizons)

Reduced matrix: 20 to 200 cm (8 to 79 in) (2Bg and 2Cg horizons)

Redoximorphic concentrations: 20 to 200 cm (8 to 79 in) (2Bg and 2Cg horizons)

Aquic conditions: 20 to 200 cm (8 to 79 in) (2Bg and 2Cg horizons)

ADDITIONAL DATA:

User pedon ID: 2021AK290742

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National Cooperative Soil Survey
U.S.A.