Soil Survey of Sweet Grass County Area, Montana - Soil Data Mart

142 Soil Survey
Tibson Series
Depth class: Very deep (greater than 60 inches)
Drainage class: Well drained
Permeability: Moderate (0.6 to 2.0 inches/hour)
Landform: Landslide, moraine, and mountain
Parent material: Gravelly till
Slope range: 4 to 70 percent
Elevation range: 6,000 to 7,500 feet
Mean annual precipitation: 20 to 25 inches
Mean annual air temperature: 36 to 38 degrees F
Frost-free period: 50 to 70 days
Taxonomic Class: Loamy-skeletal, mixed,
superactive Calcic Haplocryolls
Typical Pedon
Tibson gravelly loam, in an area of Tibson, extremely
bouldery-Bridger, extremely bouldery-Adel complex,
8 to 35 percent slopes, extremely bouldery, in an area
of rangeland, 100 feet north and 1,600 feet east of
the southwest corner of sec. 13, T. 3 S., R. 13 E.;
USGS Squaw Peak topographic quadrangle (lat.
45 o 34'06" N.; long. 110 o 04'03" W.)
A—0 to 7 inches; dark grayish brown (10YR 4/2)
gravelly loam, very dark gray (10YR 3/1) moist;
weak fine granular structure; soft, very friable,
slightly sticky, slightly plastic; many very fine and
fine roots; common very fine and fine pores;
15 percent gravel; 5 percent cobbles; slightly
alkaline (pH 7.6); abrupt wavy boundary.
Bk1—7 to 19 inches; pale brown (10YR 6/3) very
gravelly loam, dark grayish brown (10YR 4/2)
moist; weak fine subangular blocky structure; soft,
friable, slightly sticky, slightly plastic; common fine
and many very fine roots; common very fine and
fine pores; few fine and medium soft masses of
lime; 25 percent gravel; 10 percent cobbles;
violently effervescent; moderately alkaline
(pH 8.0); clear wavy boundary.
Bk2—19 to 31 inches; very pale brown (10YR 7/3)
very gravelly loam, brown (10YR 4/3) moist; weak
medium subangular blocky structure; soft, friable,
slightly sticky, slightly plastic; common very fine
and fine roots; few very fine and fine pores;
common fine and medium masses of lime;
25 percent gravel; 15 percent cobbles; violently
effervescent; moderately alkaline (pH 8.2); clear
wavy boundary.
Bk3—31 to 60 inches; very pale brown (10YR 8/3)
very gravelly loam, pale brown (10YR 6/3) moist;
weak coarse prismatic structure; soft, friable,
slightly sticky, slightly plastic; few very fine and
fine roots; few very fine and fine pores; many fine
and medium masses of lime; 30 percent gravel;
15 percent cobbles; violently effervescent;
moderately alkaline (pH 8.4).
Range in Characteristics
Soil temperature: 37 to 45 degrees F
Moisture control section: Between 4 and 12 inches
Thickness of the mollic epipedon: 7 to 12 inches
Depth to the Bk horizon: 6 to 12 inches
Note: Some pedons have a Bw horizon.
A horizon
Hue: 10YR
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2
Texture (less than 2 mm): Loam
Clay content: 18 to 27 percent
Content of rock fragments: 15 to 60 percent—0 to
15 percent stones and cobbles; 15 to
45 percent gravel or channers
Reaction: pH 7.4 to 7.8
Bk1 horizon
Hue: 10YR or 2.5Y
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 4 or 6
Texture (less than 2 mm): Loam, clay loam, or
sandy clay loam
Clay content: 18 to 30 percent
Content of rock fragments: 35 to 60 percent—0 to
25 percent stones and cobbles; 20 to
50 percent gravel or channers
Calcium carbonate equivalent: 20 to 35 percent
Reaction: pH 7.9 to 8.4
Bk2 and Bk3 horizons
Hue: 10YR or 2.5Y
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 4
Texture (less than 2 mm): Loam, clay loam, or
sandy clay loam
Clay content: 18 to 30 percent
Content of rock fragments: 35 to 60 percent—0 to
25 percent stones and cobbles; 20 to
50 percent gravel or channers
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 7.9 to 8.4
Ticell Series
Depth class: Shallow (10 to 20 inches)
Drainage class: Well drained
Permeability: Moderate (0.6 to 2.0 inches/hour)
Landform: Hill and knoll on plain