LOCATION TIBS MTEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, frigid Typic Haplustepts
TYPICAL PEDON: Tibs cobbly clay loam, in forestland (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; forest litter of undecomposed and decomposed needles, twigs, and cones. (1 to 3 inches thick)
A1--1 to 3 inches; reddish brown (5YR 4/3) cobbly clay loam, dark reddish brown (5YR 3/3) moist; strong fine granular structure; soft, very friable, moderately sticky, moderately plastic; many fine, medium, and coarse roots; 20 percent angular cobbles; 10 percent angular gravel; slightly effervescent; slightly alkaline (pH 7.8); abrupt wavy boundary. (1 to 3 inches thick)
A2--3 to 7 inches; reddish brown (2.5YR 4/4) cobbly clay loam, dark reddish brown (2.5YR 3/4) moist; weak fine subangular blocky structure; slightly hard, friable, moderately sticky, moderately plastic; many fine, medium, and coarse roots; common medium and many fine pores; 25 percent angular cobbles; 10 percent angular gravel; slightly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (2 to 6 inches thick)
Bk--7 to 13 inches; reddish brown (5YR 4/4) very cobbly clay loam, dark reddish brown (5YR 3/4) moist; strong fine subangular blocky structure; slightly hard, friable, moderately sticky, moderately plastic; many fine, medium, and coarse roots; common medium and many fine pores; 25 percent angular cobbles; 15 percent angular gravel; common fine soft masses of lime; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (5 to 10 inches thick)
C1--13 to 31 inches; reddish brown (2.5YR 5/4) very cobbly clay, reddish brown (2.5YR 4/4) moist; strong fine angular blocky structure; hard, friable, moderately sticky, moderately plastic; many fine, medium, and coarse roots in the upper part; common fine, medium, and coarse roots in the lower part; many fine and medium pores; 30 percent angular cobbles; 20 percent angular gravel; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (8 to 18 inches thick)
C2--31 to 60 inches; red (2.5YR 5/6) very cobbly clay, red (2.5YR 4/6) moist; moderate fine subangular blocky structure; hard, friable, very sticky, very plastic; common fine, medium, and coarse roots; common fine and medium pores; 35 percent angular cobbles; 20 percent angular gravel; strongly effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Fergus County, Montana; 1,320 feet west and 1,850 feet north of the southeast corner of sec. 7, T. 12 N., R. 21 E.
RANGE IN CHARACTERISTICS:
Soil temperature: 41 to 45 degrees F
Moisture control section: Between 4 and 12 inches
Control section: 35 to 55 percent clay and 35 to 60 percent Content of rock fragments
Depth to the Bk horizon: 5 to 9 inches
A1 horizon
Hue: 2.5YR, 5YR, 7.5YR, or 10YR
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 2 or 3
Clay content: 30 to 40 percent
Content of rock fragments: 5 to 35 percent--0 to 25 percent angular cobbles; 5 to 10 percent angular gravel
Reaction: pH 6.1 to 8.4
A2 horizon
Hue: 2.5YR, 5YR, 7.5YR, or 10YR
Value: 4 or 5 dry; 3 or 4 moist
Clay content: 30 to 40 percent
Content of rock fragments: 5 to 35 percent--0 to 25 percent angular cobbles; 5 to 10 percent angular gravel
Reaction: pH 6.1 to 8.4
Bk horizon
Hue: 2.5YR, 5YR, 7.5YR, or 10YR
Value: 4 to 6 dry; 3 or 4 moist
Texture: Clay loam or clay
Clay content: 35 to 55 percent
Content of rock fragments: 35 to 60 percent--25 to 40 percent angular cobbles; 10 to 20 percent angular gravel
Calcium carbonate equivalent: 5 to 10 percent
Reaction: pH 6.6 to 8.4
C1 horizon
Hue: 2.5YR, 5YR, 7.5YR, or 10YR
Value: 4 to 6 dry; 3 or 4 moist
Texture: Clay loam or clay
Clay content: 35 to 55 percent
Content of rock fragments: 35 to 60 percent--25 to 40 percent angular cobbles; 10 to 20 percent angular gravel
Reaction: pH 7.9 to 8.4
C2 horizon
Hue: 2.5YR, 5YR, 7.5YR, or 10YR
Value: 5 to 7 dry; 4 or 5 moist
Chroma: 3, 4, or 6
Texture: Clay loam or clay
Clay content: 35 to 55 percent
Content of rock fragments: 40 to 60 percent--30 to 45 percent angular cobbles; 10 to 15 percent angular gravel
Reaction: pH 7.9 to 8.4
COMPETING SERIES: None
GEOGRAPHIC SETTING:
Landform: Hills and mountains
Elevation: 4,000 to 6,200 feet
Slope: 2 to 60 percent
Parent material: Colluvium derived from reddish-colored shales interbedded with calcareous sandstone
Climate: Cool with long, cold winters, moist springs, and warm summers
Mean annual precipitation: 15 to 24 inches
Mean annual temperature: 39 to 43 degrees F
Frost-free period: 80 to 110 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Maiden (MT) occurs on similar landforms; has a calcic horizon.
Whitecow (MT) occurs on similar landforms; has a calcic horizon.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability
USE AND VEGETATION: Tibs soils are used mainly for forest products, rangeland, watershed, and recreation. The potential native vegetation is mainly ponderosa pine and Douglas-fir with an understory of common snowberry, white spiraea, Woods rose, Oregongrape, kinnikinnick, meadowrue, Richardsons needlegrass, western yarrow, timothy, pinegrass, common juniper, and russet buffaloberry.
DISTRIBUTION AND EXTENT: Tibs soils are of limited extent in the mountains of central Montana; MLRA 43B, 44, and 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Fergus County, Montana, 1979
REMARKS:
Soil interpretation record: MT0316
11/06: Classification updated from Clayey-skeletal, mixed, superactive, calcareous, frigid, Typic Ustorthents. Ck horizon from 7 to 13 inches changed to Bk horizon.