LOCATION BEAVERTON MT+WYEstablished Series
TAXONOMIC CLASS: Loamy-skeletal over sandy or sandy-skeletal, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Beaverton gravelly loam, in native grassland. (Colors are for dry soil unless otherwise noted)
A--0 to 2 inches; grayish brown (10YR 5/2) gravelly loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and nonplastic; many very fine and medium roots; many fine and medium pores; 20 percent pebbles; neutral (pH 6.8); clear irregular boundary. (2 to 5 inches thick)
Bt1--2 to 9 inches; dark brown (10YR 4/3) very gravelly clay loam, dark brown (10YR 3/3) moist; moderate medium prismatic structure parting to strong fine and very fine blocky; hard, friable, sticky and plastic; common very fine and medium roots; many fine and very fine tubular pores and few medium tubular pores; continuous faint dark grayish brown (10YR 4/2) clay films on faces of peds and on pebbles; 35 percent pebbles; neutral (pH 6.8); clear smooth boundary.
Bt2--9 to 14 inches; dark grayish brown (10YR 4/2) extremely gravelly clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many fine tubular pores; common faint dark grayish brown (10YR 4/2) clay films on faces of peds and on pebbles; 45 percent pebbles and 15 percent cobbles; neutral (pH 7.3); clear irregular boundary. (Combined Bt horizons 8 to 20 inches thick)
2Bk1--14 to 20 inches; grayish brown (2.5Y 5/2) extremely gravelly loamy sand, dark grayish brown (2.5Y 4/2) moist; single grain; loose; many fine continuous roots; faint lime casts and coating on sides and undersides of pebbles; 65 percent pebbles; disseminated lime; strongly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (4 to 35 inches thick)
2Bk2--20 to 60 inches; grayish brown (2.5Y 5/2) extremely gravelly sand, dark grayish brown (2.5Y 4/2) moist; single grain; loose; few fine roots; common faint lime coating and casts on undersides of pebbles in upper part; 65 percent pebbles and 5 percent cobbles; disseminated lime; strongly effervescent; moderately alkaline (pH 8.0). (0 to 45 inches thick)
TYPE LOCATION: Glacier County, Montana; 1,000 feet north and 200 feet east of the SW corner of sec. 31, T. 33 N., R. 10 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 47 degrees F.
Mollic epipedon thickness - 7 to 14 inches (may include all or only part of the Bt horizons).
Control section - 25 to 35 percent clay.
Depth to Bk or 2Bk horizon - 10 to 20 inches.
Bk and 2C horizon - horizons are allowed.
A horizon - Hue: 2.5Y, 10YR, or 7.5YR
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; chroma of 1 allowed in A horizons 3 inches or less in thickness.
Texture: loam, clay loam, sandy clay loam, or sandy loam
Clay content: 10 to 30 percent
Rock fragments: 5 to 60 percent--0 to 5 percent stones, 0 to 25 percent cobbles, 5 to 40 percent pebbles
Reaction: pH 6.6 to 7.8
Bt horizons - Hue: 2.5Y, 10YR, or 7.5YR
Value: 4 or 5 dry; 2, 3, or 4 moist
Chroma: 2 or 3
Texture: loam, clay loam or sandy clay loam
Clay content: 25 to 35 percent
Rock fragments: 35 to 60 percent--0 to 5 percent stones, 0 to 30 percent cobbles, 15 to 45 percent pebbles
Reaction: pH 6.6 to 7.8
2Bk1 horizon - Hue: 2.5Y, 10YR, or 7.5YR
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: loamy sand, loamy coarse sand or sand
Clay content: 0 to 10 percent
Rock fragments: 35 to 80 percent--0 to 10 percent stones, 0 to 35 percent cobbles, 15 to 60 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
2Bk2 horizon - Hue: 2.5Y, 10YR, or 7.5YR
Value- 5 or 6 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: loamy sand, loamy coarse sand or sand
Clay content: 0 to 10 percent
Rock fragments: 35 to 80 percent--0 to 5 percent stones, 0 to 35 percent cobbles, 15 to 65 percent pebbles
Calcium carbonate equivalent: 3 to 12 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Harol (UT) - do not have a Bk or 2Bk horizon or carbonates within depths of 40 inches.
Shirttail (SD) - do not have a Bk or 2Bk horizon or carbonates within depths of 40 inches.
Silvercity (MT) - is 20 to 40 inches deep to the sandy-skeletal discontinuity; has an ustic moisture regime that borders on udic.
GEOGRAPHIC SETTING:
Landform - alluvial fans; stream terraces; hills; outwash plains.
Elevation - 2,400 to 6,000 feet.
Slope- 0 to 25 percent.
Parent material - gravelly alluvium or glacial outwash materials derived from a mixture of rock sources.
Climate - cool, with long, cold winters; moist springs; and warm summers.
Mean annual precipitation - 13 to 19 inches.
Mean air annual temperature - 39 to 45 degrees F.
Frost-free season - 85 to 130 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability in the solum and rapid permeability in the 2C horizon.
USE AND VEGETATION: Used mainly as rangeland, grain, and hay crops. The potential native vegetation is mainly bluebunch wheatgrass, western wheatgrass, prairie sandreed, needleandthread, little bluestem, plains muhly, sand dropseed, shrubs, and forbs.
DISTRIBUTION AND EXTENT: Throughout the northern Great Plains and Rock Mountain regions. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Milk River Area, Montana, 1928. (Benchmark soil)
REMARKS: Soil interpretation record: MT0002, MT0473, MT0673, MT1121.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the soil surface of the soil to a depth of 14 inches (A, Bt1, Bt2 horizons); argillic horizon - the zone from 2 to 14 inches (Bt1, Bt2 horizons); particle-size control section - the zone from 2 to 14 inches (Bt1, Bt2 horizons); horizon of sandy-skeletal materials - the zone from 14 to 60 inches (2Bk1, 2Bk2 horizons). secondary carbonate accumulation - the zone from 14 to 60 inches (2Bk1, 2Bk2 horizons). Beaverton soils have a frigid temperature regime and an ustic moisture regime.
The family classification was changed from Loamy-skeletal to Loamy-skeletal over sandy or sandy-skeletal in 1993.
ADDITIONAL DATA: Laboratory sample S90MT-097-001.