LOCATION CIRQUECREEK             AK

Tentative Series
SDB/MJS
08/2025

CIRQUECREEK SERIES

Depth class: very deep
Drainage class: well drained
Parent material: organic material over silty loess over sandy and gravelly residuum weathered from metamorphic rock and/or sandy and gravelly till
Landscape: mountains and foothills
Landform: saddles, mountain slopes, and hillslopes
Slope: 0 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: 32 to 103 days

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, subgelic Typic Haplogelepts

TYPICAL PEDON: Cirquecreek silt loam in a sedge and lichen community on a west facing linear, linear mountain slope on a slope of 4 percent at an elevation of 1578m (5175 ft).

Oi--0 to 4 cm (0 to 2 in); slightly decomposed plant material, dark brown (7.5YR 3/3) moist; nonsticky, nonplastic; common very fine and fine roots throughout; common medium dendritic tubular pores; 0 percent by volume; neutral (pH 6.7); clear smooth boundary (0 to 10 cm, 0 to 4 in).

A--4 to 10 cm (2 to 4 in); channery silt loam, brown (7.5YR 4/2) moist; moderate medium subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; nonsmeary; common very fine and fine roots throughout; common medium dendritic tubular pores; 10 percent gravels by volume, 15 percent channers by volume; neutral (pH 6.8); clear wavy boundary (3 to 16 cm, 2 to 6 in).

Bw--10 to 50 cm (4 to 20 in); channery silt loam, dark grayish brown (2.5Y 4/2) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; nonsmeary; common very fine and fine roots top of horizon; common medium dendritic tubular pores; 10 percent gravels by volume, 15 percent channers by volume; slightly acid (pH 6.5); clear wavy boundary (15 to 42 cm, 6 to 16 in).

2C--50 to 150 cm (20 to 59 in); very gravelly fine sandy loam, grayish brown (2.5Y 5/2) moist; single grain; slightly hard, friable, nonsticky, nonplastic; nonsmeary; 15 percent channers by volume, 30 percent gravel by volume; slightly acid (pH 6.5). (82 to 132cm, 32 to 52 in).

TYPE LOCATION: North Copper River Soil Survey Area, Alaska; latitude 61.51403, longitude -144.57924, UTM 6822436.32 north and UTM 628786.95 east, zone 6, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: gelic
Mean annual soil temperature: 0 to 5 degrees C. (32 to 41 degrees F)
Thickness of organic material: 0 to 10 cm (0 to 4 in)
Thickness of epipedon: 3 to 26 cm (1 to 10 in)
Thickness of cambic horizon: 15 to 42 cm (6 to 16 in)

Oi, Oe, Oa horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 3
Texture: Slightly decomposed organic material, or moderately decomposed organic material
Organic matter: 60 to 90 percent
Reaction class: slightly acid to neutral (pH 6.2 to 7.3)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 4
Chroma: 2 to 3
Texture: channery silt loam, very channery silt loam, gravelly silt loam, very gravelly silt loam
Sand: 24 to 46 percent
Silt: 50 to 72 percent
Clay: 4 to 12 percent
Rock fragments: 20 to 60 percent
Gravels: 8 to 27 percent
Cobbles: 0 to 11 percent
Channers: 12 to 22 percent
Organic matter: 2 to 5 percent
Reaction class: slightly acid to neutral (pH 6.2 to 7.3)

Bw horizon:
Hue: 10YR or 2.5Y
Value: 3 to 4
Chroma: 2 to 4
Texture: channery silt loam, cobbly silt loam, gravelly loam, gravelly silt loam, gravelly sandy loam
Sand: 32 to 59 percent
Silt: 36 to 64 percent
Clay: 4 to 15 percent
Rock fragments: 16 to 69 percent
Gravels: 9 to 35 percent
Cobbles: 0 to 16 percent
Channers: 7 to 18 percent
Organic matter: 0.3 to 0.9 percent
Reaction class: slightly acid to neutral (pH 6.2 to 7.3)

2C or C horizon:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 2 to 4
Texture: very gravelly fine sandy loam, very gravelly loam, very gravelly sandy loam, extremely gravelly sandy loam.
Sand: 42 to 72 percent
Silt: 16 to 46 percent
Clay: 4 to 12 percent
Rock fragments: 36 to 76 percent
Gravels: 28 to 38 percent
Cobbles: 0 to 20 percent
Channers: 8 to 18 percent
Organic matter: 0 to 0.3 percent
Reaction class: slightly acid to neutral (pH 6.2 to 7.3)

COMPETING SERIES: These are the Kalasik Creek and Reindeerhills soils.
Kalasik Creek soils have a paralithic contact within 150 cm (59 in) of the soil surface and a mean annual soil temperature of 1 to 0 degrees C. (30 to 32 degrees F)
Reindeerhills soils lack a lithologic discontinuity.

GEOGRAPHIC SETTING:
Elevation: 600 to 1600 meters (1970 to 5250 ft)
Parent material: organic material over silty loess over sandy and gravelly residuum weathered from metamorphic rock and/or sandy and gravelly till
Landform: saddles, mountain slopes, and hillslopes
Slopes: 0 to 40 percent
Mean annual precipitation: 300 to 1400 mm (12 to 55 in)
Mean annual air temperature: -5 to -1 degrees C. (23 to 30 degrees F)
Frost free period: 32 to 103 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fields, Fourthofjuly, Greylingcreek, Stibnite, Tasta, and Tsina soils.
Fields soils are well drained, have an umbric epipedon, a lithic contact within 200cm (79 in) of the soil surface, and occur on mountains.
Fourthofjuly soils are well drained, have a folistic epipedon, and occur on mountain valleys and stream terraces.
Greylingcreek soils are excessively drained, lack a cambic horizon, and occur in mountain valleys and moraines.
Stibnite is well drained, has less than 35 percent coarse fragments in its particle size control section, lacks a lithologic discontinuity, and occurs in till plains, mountains, kames and kettles.
Suslota soils are well drained, have an umbric epipedon, and occur on mountain slopes and hillsides.
Tasta soils are well drained, have mollic epipedons, and occur on mountain slopes above 800 m (2600 ft) elevation.
Tsina soils are well drained, lack a cambic horizon, 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 Oi horizon, moderately high in the A and Bw horizon, and high in the 2C horizon.
Permeability: Very rapid in the Oi horizon, moderate in the A and Bw horizon, and moderately rapid in the 2C horizon
Runoff: low

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: upland sedges, lichens, grass and forbs

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

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: 29 to 104 cm (11 to 41 in)

Ochric epipedon: 0 to 10 cm (0 to 4 in) (Oi and A horizon)

Cambic horizon: 10 to 50 cm (4 to 20 in) (Bw horizon)

Lithologic discontinuity: 50 to 150 cm (20 to 59 in) (2C horizon)

ADDITIONAL DATA:

User pedon Id: 2022AK261147

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National Cooperative Soil Survey
U.S.A.