LOCATION TIBSON                  MT+WY

Established Series
Rev. SGV-JJU-RJS
03/2012

TIBSON SERIES


The Tibson series consists of very deep, well drained soils that formed in alpine till, alluvium, colluvium or slide deposits derived mainly from limestone, dolomite, sandstone and argillite rock. These soils are on moraines, stream terraces, alluvial fans, fan remnants, escarpments, mountains, hills, ridges and landslides. Slopes are 0 to 70 percent. Mean annual precipitation is about 22 inches, and mean annual air temperature is about 39 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Ustic Calcicryolls

TYPICAL PEDON: Tibson cobbly loam, in native vegetation (colors are for dry soil unless otherwise noted).

A--0 to 4 inches; very dark grayish brown (10YR 3/2) cobbly loam, black (10YR 2/1) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots, and common medium roots; common very fine irregular pores; 10 percent gravel and 10 percent cobbles; slightly alkaline (pH 7.6); clear wavy boundary. (3 to 7 inches thick)

Bw--4 to 8 inches; dark brown (10YR 3/3) cobbly loam, very dark brown (10YR 2/2) moist; moderate fine prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; common very fine irregular pores; 10 percent gravel and 10 percent cobbles; slightly effervescent; slightly alkaline (pH 7.8); gradual wavy boundary. (0 to 6 inches thick)

Bk1--8 to 14 inches; pale brown (10YR 6/3) very cobbly clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, firm, slightly sticky and moderately plastic; common very fine and fine roots; common fine tubular pores; 20 percent gravel and 15 percent cobbles; calcium carbonate coats in pores, and many medium masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (5 to 12 inches thick)

Bk2--14 to 60 inches; pale brown (10YR 6/3) very gravelly clay loam, brown (10YR 5/3) moist; weak coarse prismatic structure; very hard, firm, slightly sticky and moderately plastic; common very fine roots to 42 inches, and few very fine roots below this depth; 30 percent gravel and 20 percent cobbles; common medium masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.2).

TYPE LOCATION: Teton County, Montana; 2,500 feet south and 800 feet east of the northwest corner of sec. 4, T. 24N, R. 8W.

RANGE IN CHARACTERISTICS:
Soil temperature - 36 to 45 degrees F.
Mollic epipedon thickness - 7 to 15 inches
Clay content of control section - 18 to 35 percent
Rock fragments in control section - 35 to 60 percent
Depth to calcic horizon - 6 to 15 inches

A horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2; dry or moist
Texture: loam or sandy loam
Clay content: 15 to 27 percent
Rock fragments: 5 to 60 percent--10 to 45 percent gravel, 0 to 40 percent cobbles and stones
Calcium carbonate equivalent: 0 to 5 percent
Reaction: pH 7.0 to 8.4

Bw horizon
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: loam or clay loam
Clay content: 18 to 30 percent
Rock fragments: 5 to 65 percent--5 to 45 percent gravel, 0 to 20 percent cobbles and stones
Calcium carbonate equivalent: 0 to 5 percent
Reaction: pH 7.8 to 8.4

Bk1 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 6; dry or moist
Texture: loam, clay loam or sandy clay loam
Clay content: 18 to 35 percent
Rock fragments: 35 to 60 percent--20 to 50 percent gravel, 0 to 25 percent cobbles and stones
Calcium carbonate equivalent: 5 to 35 percent
Reaction: pH 7.9 to 8.4

Bk2 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 6; dry or moist
Texture: loam, clay loam or sandy clay loam
Clay content: 18 to 35 percent
Rock fragments: 35 to 60 percent--20 to 50 percent gravel, 0 to 25 percent cobbles and stones
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 7.9 to 8.4

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Landform - moraines, stream terraces, alluvial fans, fan remnants, escarpments, mountains, hills, ridges and landslides
Elevation - 4,490 to 9,300 feet
Slope - 0 to 70 percent
Parent material - alpine till, alluvium, colluvium or slide deposits derived mainly from limestone, dolomite, sandstone and argillite rock
Climate - long, cold winters; cool, moist springs; short summers
Mean annual precipitation - 14 to 25 inches
Mean annual air temperature - 34 to 43 degrees F.
Frost-free period - 30 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed.

DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.

USE AND VEGETATION: Tibson soils are used mainly as rangeland. Potential native vegetation is bluebunch wheatgrass, rough fescue, Idaho fescue, Columbia needlegrass, shrubby cinquefoil, creeping juniper, and forbs. These soils also support low-density stands of limber pine, Rocky Mountain juniper, and Douglas-fir.

DISTRIBUTION AND EXTENT: These soils are of moderate extent. MLRAs - 43B, 44B, 46.

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

SERIES ESTABLISHED: Choteau-Conrad Area Soil Survey, Teton County, Montana, 1991; proposed in Teton County, Montana, 1984.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 8 inches (A, Bw horizons)
Calcic horizons - from 8 to 60 inches (Bk1, Bk2 horizon)
Particle-size control section - from 10 to 40 inches (part of Bk1, part of Bk2 horizons)

Tibson soils have a cryic temperature regime and an ustic moisture regime.

ADDITIONAL DATA: Soil interpretation record - MT0883.

Note: Based on the profile description, the classification changed from a Calcic Haplocryolls to an Ustic Calcicryolls (07/2008).


National Cooperative Soil Survey
U.S.A.