LOCATION STORYHILL MTEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Storyhill cobbly loam, in rangeland (colors
are for dry soil unless otherwise noted).
A--0 to 10 inches; very dark grayish brown (10YR 3/2) cobbly loam, black (10YR 2/1) moist; moderate fine subangular blocky structure parting to strong medium granular; soft, friable, moderately sticky and very plastic; many very fine roots, common fine and medium roots, few coarse roots; 10 percent pebbles, 10 percent cobbles; slightly acid (pH 6.2); clear smooth boundary. (8 to 15 inches thick)
Bt1--10 to 21 inches; yellowish brown (10YR 5/4) very cobbly clay, dark yellowish brown (10YR 3/4) moist; moderate medium prismatic structure; slightly hard, very firm, very sticky and very plastic; common distinct clay films on faces of peds and lining pores; common very fine and fine roots, few medium roots; 20 percent pebbles, 20 percent cobbles; neutral (pH 6.8); gradual wavy boundary.
Bt2--21 to 32 inches; yellowish brown (10YR 5/4) very cobbly clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, very firm, moderately sticky and very plastic; common distinct clay films on faces of peds and lining pores; common very fine and few fine roots; 25 percent pebbles, 20 percent cobbles; slightly alkaline (pH 7.6); clear wavy boundary. (Combined thickness of Bt horizons is 12 to 32 inches).
Bk--32 to 60 inches; pale brown (10YR 6/3) very cobbly sandy clay loam, brown (10YR 5/3) moist; weak medium subangular blocky structure; few very fine and fine roots; 30 percent pebbles, 30 percent cobbles; common fine threads of lime, common lime coatings on coarse fragments; violently effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Gallatin County, Montana; 600 feet north and 400 feet east of the southwest corner of sec. 33, T.1S., R.6E.
RANGE IN CHARACTERISTICS:
Soil temperature - 39 to 43 degrees F.
Moisture control section - between 4 and 12 inches; not dry in all parts for 45 consecutive days.
Mollic epipedon thickness - 10 to 15 inches.
Depth to the calcic horizon - 20 to 40 inches.
A horizon - Value: 3 or 4 dry; 2 or 3 moist
Clay content: 20 to 27 percent
Rock fragments: 15 to 45 percent-- 5 to 25 percent pebbles, 10 to 20 percent cobbles, 0 to 10 percent stones
Reaction: pH 6.1 to 7.3
Bt horizons - Value: 4 or 5 dry; 3 or 4 moist
Chroma: 3 or 4
Texture: clay, clay loam
Clay content: 35 to 50 percent
Rock fragments: 35 to 60 percent-- 15 to 30 percent pebbles,
15 to 30 percent cobbles, 0 to 5 percent stones
Reaction: pH 6.1 to 7.8
Bk horizon - Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: clay loam, sandy clay loam
Clay content: 30 to 40 percent
Rock fragments: 40 to 70 percent-- 20 to 30 percent pebbles,
20 to 40 percent cobbles, 0 to 5 percent stones
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Rionutria (NM) - has a lithic contact at 20 to 40 inches.
Roy (MT) - does not have a calcic horizon.
GEOGRAPHIC SETTING:
Landform - relict stream terraces and hills.
Elevation - 5,000 to 6,000 feet.
Slope - 4 to 45 percent.
Parent material - alluvium and colluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 18 to 22 inches.
Mean annual air temperature - 37 to 41 degrees F.
Frost-free period - 80 to 95 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Storyhill soils are used mainly for rangeland and wildlife habitat. Potential native vegetation may include subalpine needlegrasses, Idaho fescue, bluebunch wheatgrass, mountain brome, sedges, lupine, sticky geranium, sagebrush, common snowberry and rose as well as other grasses, forbs and woody shrubs.
DISTRIBUTION AND EXTENT: Storyhill soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Gallatin County, Montana, 1997.
REMARKS: Soil interpretation records: MT1452, MT1603. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 10 inches (A horizon); an argillic horizon from 10 to 32 inches (Bt1, Bt2 horizons); a calcic horizon from 32 to 60 inches (Bk horizon); a particle-size control section from 10 to 30 inches (Bt1, Bt2 horizons). Storyhill soils have a frigid temperature regime and an ustic moisture regime.