LOCATION EAGLECREEK MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Udic Haplustalfs
TYPICAL PEDON: Eaglecreek loam, in woodland (colors are for dry soil unless otherwise noted).
Oi--0 to 1 inch; partly decomposed needles and twigs.
A--1 to 5 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak thin platy structure parting to strong fine granular; slightly hard, very friable, slightly sticky and slightly plastic; many fine and very fine and few medium and coarse roots; 10 percent pebbles; slightly acid (pH 6.4); abrupt wavy boundary. (3 to 6 inches thick)
E--5 to 11 inches; grayish brown (10YR 5/2) loam, dark grayish brown (10YR 4/2) moist; weak fine and medium subangular blocky structure parting to strong fine and medium granular; slightly hard, very friable, slightly sticky and slightly plastic; many fine and very fine and few medium and coarse roots; many very fine tubular pores; 10 percent pebbles; slightly acid (pH 6.4); clear wavy boundary. (3 to 6 inches thick)
Bt1--11 to 19 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; strong medium subangular blocky structure; very hard, friable; moderately sticky and moderately plastic; common fine and very fine and few medium and coarse roots; many very fine tubular pores; many distinct clay films on faces of peds; few skeletans on faces of peds in upper 3 inches; 10 percent pebbles; slightly acid (pH 6.4); clear wavy boundary. (6 to 17 inches thick)
Bt2--19 to 33 inches; grayish brown (10YR 5/2) gravelly sandy clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, very friable; moderately sticky and slightly plastic; common fine and very fine and few medium roots; many very fine tubular pores; common faint clay films on faces of peds and bridging sand grains; 20 percent pebbles; neutral (pH 6.8); clear wavy boundary. (6 to 18 inches thick)
R--33 inches; hard igneous bedrock.
TYPE LOCATION: Chouteau County, Montana; 2,500 feet east and 1,400 feet north of the SW corner of sec. 2, T. 27 N., R. 15 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 45 degrees F.
Moisture control section - between 4 and 12 inches, and is moist in some or all parts April through July 15 and dry in some or all parts less than 45 days during summer.
Depth to Bt1 horizon - 6 to 11 inches.
Depth to bedrock - 20 to 40 inches.
The A horizon when mixed to a depth of 7 inches does not meet the requirements for a mollic epipedon.
Dark colors are inherent from the parent material; a Bt3 and a Cr horizon up to 10 inches thick consisting of weathered grus-like igneous rock are allowed.
A horizon - Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2
Clay content: 12 to 22 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Reaction: pH 6.1 to 6.5
E horizon - Hue: 10YR or 7.5YR
Value: 4, 5, or 6 dry; 3 or 4 moist
Texture: loam or sandy loam
Clay content: 10 to 18 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Reaction: pH 6.1 to 6.5
Bt horizons - Hue: 10YR, 7.5YR, or 5YR
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: loam, clay loam, or sandy clay loam
Clay content: 18 to 35 percent
Rock fragments: 5 to 25 percent--0 to 5 percent cobbles, 5 to 20 percent pebbles
Reaction: pH 6.1 to 7.3
COMPETING SERIES:
Lobat (NM) - more than 40 inches deep.
GEOGRAPHIC SETTING:
Landform - hills.
Elevation - 4,000 to 4,800 feet.
Slope - 25 to 45 percent.
Parent material - colluvium or residuum from dark, basic igneous bedrock.
Climate - long, cold winters; moist springs; and warm, dry summers.
Mean annual air temperature - 40 to 43 degrees F.
Mean annual precipitation - 18 to 24 inches.
Frost-free period - 70 to 100 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Eaglecreek soils are used for timber production and understory grazing. The potential native vegetation is an overstory of ponderosa pine and Douglas fir with an understory of pinegrass, common snowberry, white spirea, rose, and heartleaf arnica.
DISTRIBUTION AND EXTENT: Eaglecreek soils are of small extent in the Bearpaw Mountains in north central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Chouteau County, Montana, 1992; proposed in Chouteau County, Montana, 1991. Eaglecreek is from the name of a perennial stream.
REMARKS: Soil interpretation record: MT1338. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 11 inches (A, E horizons); an argillic horizon from 11 to 33 inches and a particle-size control section from 11 to 31 inches (Bt horizons); a lithic contact at a depth of 33 inches (R horizon). Eaglecreek soils have a frigid temperature regime and an ustic moisture regime.
ADDITIONAL DATA: Lincoln laboratory data--S91MT-015-831.