LOCATION BRASSPANCREEK           AK

Established Series
MJS/CBB
04/2026

BRASSPANCREEK SERIES

Depth class: very deep
Drainage class: well drained
Parent material: sandy and gravelly alluvium derived from metamorphic and sedimentary rock
Landscape: mountains
Landform: flood plains, drainageways
Slopes: 0 to 5 percent
Mean annual precipitation: about 500 mm (19.68 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 65 to 85 days

TAXONOMIC CLASS: Sandy-skeletal, mixed Oxyaquic Cryorthents

TYPICAL PEDON: Brasspancreek gravelly sandy loam in a willow and bluejoint community on a concave, linear toeslope on a slope of 0 percent at an elevation of 454 m (1490 ft)

Oi--0 to 4 cm (0 to 1.5 in); gravelly slightly decomposed plant material, very dark brown (7.5YR 2.5/2) moist, brown (7.5YR 4/2) dry; many very fine and coarse roots and few fine roots throughout; 20 percent gravel; neutral (pH 6.8); clear wavy boundary. (2 to 5 cm, 1 to 2 in thick)

A--4 to 6 cm (1.5 to 2.5 in); gravelly sandy loam, dark brown (7.5YR 3/2) moist, brown (7.5YR 5/2) dry; moderate medium subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; many very fine, fine, and coarse roots throughout; very fine irregular pores; 20 percent gravel; neutral (pH 7.2); clear wavy boundary. (1 to 8 cm, 0.5 to 3 in thick)

C--6 to 200 cm (2.5 to 79 in); extremely gravelly sand, dark grayish brown (10YR 4/2) moist, light brownish gray (10YR 6/2) dry; single grain; loose, nonsticky, nonplastic; nonsmeary; few very fine, fine, and coarse roots at top of horizon; very fine irregular pores; 30 percent cobbles and 50 percent gravel by volume; neutral (pH 7.2). (187 to 197 cm, 74 to 78 in thick)

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64 degrees 34 minutes 36.42 seconds north, longitude 159 degrees 49 minutes 9.94 seconds west, datum WGS84, UTM north 7161542.86 and UTM east 460749.12, zone 4W, datum WGS84

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: 0 to 3 degrees C. (21 to 37 degrees F.)
Thickness of organic material: 2 to 5 cm (1 to 2 in)
Thickness of ochric epipedon: 3 to 13 cm (1 to 5 in)

Oi horizon:
Hue: 7.5YR, 5YR or 10YR
Value: 2 to 2.5 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: slightly decomposed plant material or its gravelly analogues
Rock fragments: 0 to 30 percent
Gravels: 0 to 30 percent
Organic matter: 60 to 90 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: sandy loam, very fine sandy loam or their gravelly analogues
Sand: 45 to 70 percent
Silt: 18 to 50 percent
Clay: 1 to 12 percent
Rock fragments: 0 to 34 percent
Gravels: 0 to 34 percent
Organic matter: 2 to 8 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)

C horizon:
Hue: 10YR or 2.5Y
Value: 3 to 4 moist, 5 to 6 dry
Chroma: 2 to 3
Texture: sand, coarse sand or their gravelly analogues
Sand: 86 to 99 percent
Silt: 0 to 13 percent
Clay: 1 to 8 percent
Rock fragments: 40 to 89 percent
Gravels: 30 to 70 percent
Cobbles: 5 to 35 percent
Organic matter: 0.1 to 2 percent
Reaction class: slightly acid to neutral (pH 6.1 to 7.3)

COMPETING SERIES: These are the Chiniak, Fingers, Kocacho, Pasagshak, Puffin, and Tangoe (AK) series.
Chiniak soils have marine deposits in the substratum, are moderately well drained, and occur on island beaches, beach plains, and berms.
Fingers soils have an oxygenated water table below a depth of 25 cm (10 in) and occur on outwash plains.
Kocacho soils are saturated at depths between of 25 to 50 cm (10 to 20 in) in May through July and occur on depressions on stream terraces.
Pasagshak soils have a lithologic discontinuity between 20 and 41 cm (8 to 16 in) and occur on islands.
Puffin soils have free carbonates below 70 cm (28 in) and do not have organic horizons.
Tangoe soils have stratified coarse-loamy textures at depths between 5 to 25 cm (2 to 10 in) and a lithologic discontinuity.

GEOGRAPHIC SETTING:
Elevation: 280 to 580 meters (910 to 1905 feet)
Parent material: sandy and gravelly alluvium derived from metamorphic and sedimentary rock
Landform: flood plains, drainageways
Slopes: 0 to 5 percent
Mean annual precipitation: 400 to 600 mm (16 to 24 in)
Mean annual air temperature: -6 to -2 degrees C. (21 to 28 degrees F.)
Frost free period: 65 to 85 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Tumi, Myoukchuk, Napaaktuk, and Tatkik soils.
Tumi soils have a lithic contact at depths between 43 to 181 cm (17 to 71 in) and occur on mountain slopes and valley sides.
Myoukchuk soils have a paralithic contact at depths between 84 to 146 cm (33 to 57 in) and occur on mountain slopes and valley sides.
Napaaktuk soils are moderately well drained and have aquic conditions below 58 cm (23 in).
Tatkik soils are poorly or somewhat poorly drained and have a lithologic discontinuity in the substratum.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in the Oi and C horizons and moderately high to high in the A horizon
Permeability: rapid to very rapid in the Oi horizon, moderate to rapid in the A horizon, and very rapid in the C horizon
Runoff: very low to negligible

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: feltleaf willow, moss, bluejoint, tealeaf willow, dwarf raspberry, dwarf scouringrush, ledge stonecrop, yellow thimbleweed, dwarf marsh violet, and Alaska bog willow.

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

Ochric epipedon: 0 to 6 cm (0 to 2 in) (Oa and A horizon)

ADDITIONAL DATA:

User pedon ID: 2021AK290804

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National Cooperative Soil Survey
U.S.A.