LOCATION FINN                    MT

Established Series
Rev. ADI-KTS-RJS
04/2011

FINN SERIES

The Finn series consists of very deep, poorly and very poorly drained soils that formed in mixed alluvium. These soils are on flood plains, stream terraces, alluvial fans, outwash plains, drainageways, depressions and landslides. Slopes are 0 to 4 percent. Mean annual precipitation is about 20 inches and mean annual air temperature is about 38 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Typic Cryaquolls

TYPICAL PEDON: Finn gravelly loam, in rangeland, (colors are for moist soil unless otherwise noted).

Oi--0 to 2 inches; partially decomposed organic matter. (2 to 8 inches thick)

A--2 to 12 inches; black (10YR 2/1) gravelly loam, grayish brown (10YR 5/2) dry; moderate fine granular structure; slightly hard, very friable, nonsticky and slightly plastic; many very fine and fine, and common medium roots; many very fine and fine discontinuous pores; 10 percent gravel and 5 percent cobbles; strongly acid (pH 5.2); clear smooth boundary. (7 to 15 inches thick)

Bw1--12 to 18 inches; dark yellowish brown (10YR 3/4) very gravelly loam, yellowish brown (10YR 5/4) dry; common fine distinct yellowish brown (10YR 5/8), brownish yellow (10YR 6/8) dry redox concentrations; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine and fine roots; many very fine and fine discontinuous pores; 35 percent gravel and 5 percent cobbles; strongly acid (pH 5.4); clear smooth boundary. (6 to 12 inches thick)

Bw2--18 to 24 inches; dark brown (10YR 3/3) very gravelly sandy clay loam, brown (10YR 5/3) dry; common fine distinct yellowish brown (10YR 5/8), brownish yellow (10YR 6/8) dry redox concentrations; weak fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; many very fine and fine discontinuous pores; 40 percent gravel and 10 percent cobbles; moderately acid (pH 5.6); gradual wavy boundary. (0 to 9 inches thick)

C--24 to 60 inches; dark yellowish brown (10YR 4/4) very gravelly sandy clay loam, light yellowish brown (10YR 6/4) dry; many medium distinct yellowish brown (10YR 5/8), brownish yellow (10YR 6/8) dry redox concentrations; massive; hard, firm, slightly sticky and slightly plastic; few very fine and fine roots; many very fine and fine discontinuous pores; 40 percent gravel and 15 percent cobbles; moderately acid (ph 6.0).

TYPE LOCATION: Deer Lodge County, Montana; 1,500 feet north and 700 feet west of the SE corner of sec. 5, T. 2 N., R. 12 W.

RANGE IN CHARACTERISTICS:
Soil temperature - 35 to 41 degrees F.
Mollic epipedon thickness - 10 to 15 inches
Depth to seasonal high water table - ponded to 24 inches

Note: Some pedons may have a Cg horizon.

A horizon
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1 or 2; dry or moist
Texture: loam or silt loam
Clay content: 18 to 27 percent
Rock fragments: 0 to 35 percent--0 to 30 percent gravel, 0 to 5 percent cobbles
Reaction: pH 5.1 to 7.3

Bw1 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 to 8 dry; 3 to 7 moist
Chroma: 1 to 4; dry or moist
Texture: loam or sandy loam
Clay content: 15 to 27 percent
Rock fragments: 10 to 60 percent--10 to 45 percent gravel, 0 to 15 percent cobbles
Reaction: pH 5.1 to 7.3

Bw2 horizon
Hue: 10YR, 2.5Y or 5Y; dry or moist
Value: 5 to 8 dry; 3 to 6 moist
Chroma: 1 to 4; dry or moist
Texture: loam, sandy clay loam or sandy loam
Clay content: 18 to 27 percent
Rock fragments: 35 to 65 percent--25 to 50 percent gravel, 10 to 20 percent cobbles
Reaction: pH 5.6 to 7.3

C horizon
Hue: 10YR, 2.5Y or 5Y; dry or moist
Value: 5 to 8 dry; 3 to 6 moist
Chroma: 1 to 4; dry or moist
Texture: sandy clay loam or sandy loam
Clay content: 18 to 27 percent
Rock fragments: 35 to 75 percent--20 to 60 percent gravel, 10 to 25 percent cobbles
Calcium carbonate equivalent: 0 to 5 percent
Reaction: pH 5.6 to 7.3

COMPETING SERIES:
Bywell (NM) - have a lithologic discontinuity
Lemroi (ID) - have a lithologic discontinuity
Mahaffey (ID) - have a lithologic discontinuity
Melloe (OR) - have a lithologic discontinuity

GEOGRAPHIC SETTING:
Landform - flood plains, stream terraces, alluvial fans, outwash plains, drainageways, depressions and landslides
Elevation - 5,400 to 8,450 feet
Slope - 0 to 4 percent. (slope may range to 25 percent on mountain drainageways)
Parent material - alluvium derived from mixed sources
Climate - long, cold winters; cool, moist springs; short, cool summers
Mean annual precipitation - 14 to 35 inches
Mean annual air temperature - 34 to 39 degrees F.
Frost-free period - 30 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dunkleber, Foolhen, and Mooseflat soils. Dunkleber soils consist of histic materials. Foolhen soils are fine-loamy. Mooseflat soils are fine-loamy over sandy or sandy-skeletal. These soils are on similar landform positions.

DRAINAGE AND PERMEABILITY: Very poorly and poorly drained; moderately slow permeability.

USE AND VEGETATION: Finn soils are primarily used for rangeland. The potential native vegetation is mainly sedges, rushes, willows and shrubby cinquefoil

DISTRIBUTION AND EXTENT: Finn soils are of small extent in southwestern Montana. MLRAs - 43B, 44B.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.

SERIES ESTABLISHED: Granite County, Montana, 1997; Proposed: Deer Lodge County, Montana, 1994.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 2 to 12 inches (A horizon)
Cambic horizon - from 12 to 24 inches (Bw1 and Bw2 horizons)
Particle-size control section - from 12 to 42 inches (Bw1, Bw2, and part of C horizons)

Finn soils have a cryic temperature regime and an aquic moisture regime.

Additional Information: The 2Bw2 and 2C horizons were changed to Bw2 and C2 respectively. These horizons did not meet the definition of a discontinuity (4/11/2011).

ADDITIONAL DATA: Soil interpretation record - MT1478.

---

National Cooperative Soil Survey
U.S.A.