LOCATION BEAVWAN MT
Established Series
Rev. GAR-GFB-RJS
03/2012
BEAVWAN SERIES
The Beavwan series consists of very deep, well drained soils that formed in alluvium and outwash. These soils are on stream terraces, alluvial fans or outwash fans. Slopes are 0 to 8 percent. The mean annual precipitation is about 13 inches, and the mean annual air temperature is about 42 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Calcidic Argiustolls
TYPICAL PEDON: Beavwan loam in pasture (colors are for dry soil unless otherwise noted).
A--0 to 5 inches; brown (10YR 5/3) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots, and few medium roots; 5 percent gravel; neutral (pH 7.2); clear smooth boundary. (2 to 6 inches thick)
Bt1--5 to 7 inches; brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, friable, moderately sticky and slightly plastic; common very fine and fine roots, and few medium roots; common faint clay films on faces of peds; 5 percent gravel; neutral (pH 7.2); clear wavy boundary.
Bt2--7 to 15 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; very hard, firm, moderately sticky and moderately plastic; common very fine and fine roots, and few medium roots; common faint clay films on faces of peds; 5 percent gravel; slightly alkaline (pH 7.4); clear wavy boundary. (combined thickness of Bt1 and Bt2 horizons -- 6 to 15 inches).
2Btk--15 to 22 inches; brown (10YR 5/3) very cobbly sandy clay loam, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots, and few medium roots; few faint clay films bridging sand grains; 30 percent gravel and 25 percent cobbles; calcium carbonate coats on undersides of rock fragments; slightly alkaline (pH 7.6); gradual wavy boundary. (0 to 8 inches thick)
2Bk--22 to 28 inches; pale brown (10YR 6/3) extremely gravelly sandy loam; grayish brown (10YR 5/2) moist; granular structure; soft, loose, nonsticky and nonplastic; few very fine and fine roots; 40 percent gravel and 25 percent cobbles; calcium carbonate coats on rock fragments, finely disseminated calcium carbonate; violently effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (6 to 15 inches thick)
2BCk--28 to 60 inches; variegated extremely gravelly loamy coarse sand; single grain; loose, nonsticky and nonplastic; few very fine roots; 45 percent gravel and 30 percent cobbles; calcium carbonate coats on rock fragments in upper part, finely disseminated calcium carbonate; violently effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Gallatin County, Montana; 2,450 feet south and 100 feet west of the northeast corner sec. 35, T. 1N, R. 4E.
RANGE IN CHARACTERISTICS:
Soil temperature - 40 to 47 degrees F.
Mollic epipedon thickness - 7 to 12 inches
Depth to sandy-skeletal material - 14 to 35 inches
Soil phases - moderately wet
A horizon
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: loam or sandy loam
Clay content: 12 to 27 percent
Rock fragments: 0 to 35 percent--0 to 20 percent gravel, 0 to 15 percent cobbles
Reaction: 6.6 to 7.3
Bt horizon
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 or 3; dry or moist
Texture: clay loam or sandy clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 35 percent--0 to 25 percent gravel, 0 to 10 percent cobbles
Reaction: 6.6 to 7.8
2Btk horizon
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 to 4; dry or moist
Texture: sandy clay loam, sandy loam or coarse sandy loam
Clay content: 15 to 25 percent
Rock fragments: 35 to 75 percent--20 to 35 percent gravel, 15 to 40 percent cobbles
Reaction: 7.4 to 8.4
2Bk horizon
Value: 4 to 6 dry; 4 or 5 moist
Chroma: 2 to 4; dry or moist
Texture: sandy loam or loam
Clay content: 10 to 18 percent
Calcium carbonate equivalent: 5 to 10 percent
Rock fragments: 35 to 80 percent--20 to 65 percent gravel, 10 to 40 percent cobbles
Reaction: 7.4 to 8.4
2BCk horizon
Texture: loamy sand, sand, coarse sand or loamy coarse sand
Clay content: 0 to 10 percent
Calcium carbonate equivalent: 5 to 10 percent
Rock fragments: 35 to 80 percent--30 to 65 percent gravel, 5 to 30 percent cobbles
Reaction: 7.4 to 8.4
COMPETING SERIES:
Cortyzack (CO) - Bk horizons have less than 35 percent rock fragments
Eldgin (UT) - Bk horizons have greater than 15 percent calcium carbonate
Emlin (CO) - Bk horizons have greater than 15 percent calcium carbonate
Fortlogan (MT) - deep to a paralithic contact
Hysoop (MT) - Bk horizons have greater than 15 percent calcium carbonate
Morval (NM) - Bk horizons have greater than 35 percent calcium carbonate
Notter (UT) - peak precipitation occurs in the late summer and fall
Nuley (MT) - deep to a lithic contact
Thunderhead (MT) - moderately deep to a paralithic or lithic contact
Varney (MT) - Bk horizons have greater than 35 percent calcium carbonate
Villa Grove (CO) - have an exchangeable sodium percent of 5 to 20 in the argillic horizon
GEOGRAPHIC SETTING:
Landform - stream terraces, alluvial fans, outwash fans
Elevation - 4,000 to 6,500 feet
Slope - 0 to 8 percent
Parent material - alluvium or outwash
Climate - cool with long, cold winters; moist springs; and warm summers
Mean annual precipitation - 10 to 14 inches, most of which falls as snow and spring rains
Mean annual temperature - 38 to 45 degrees F.
Frost-free period - 70 to 115 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; permeability is moderately slow above the argillic horizon and rapid below.
USE AND VEGETATION: These soils are used mainly for irrigated and nonirrigated cropland, and pasture. Native vegetation is mainly Bluebunch wheatgrass, green needlegrass, and needleandthread.
DISTRIBUTION AND EXTENT: Beavwan soils are of small extent in intermountain valleys of southwestern Montana. MLRA - 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Gallatin County, Montana, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 7 inches (A, Bt1 horizons);
Argillic horizon - from 5 to 22 inches (Bt1, Bt2, 2Btk horizons);
Calcic horizon - from 22 to 60 inches (2Bk, 2BCk horizons).
Beavwan soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
ADDITIONAL DATA: Soil interpretations records - MT1343, MT1344.
Additional information: Based on the profile description and the Range in Characteristics, the classification was revised from Aridic Argiustolls to Calcidic Argiustolls.
National Cooperative Soil Survey
U.S.A.