LOCATION SLAGAMELT               MT

Established Series
Rev: GFB-JJU-RJS
03/2012

SLAGAMELT SERIES

The Slagamelt series consists of very deep, somewhat poorly drained soils that formed in alluvium, outwash and slide deposits derived from mixed sources. These soils are on outwash plains, outwash fans, stream terraces, fan remnants, drainageways and landslides. Slopes are 0 to 15 percent. Mean annual precipitation is about 18 inches, and mean annual air temperature is about 37 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Aquic Haplocryolls

TYPICAL PEDON: Slagamelt cobbly silt loam, in aspen grove (colors are for dry soil unless otherwise noted).

Oi--0 to 1 inch; slightly decomposed matted roots, leaves and twigs; abrupt smooth boundary. (1 to 3 inches thick)

A--1 to 7 inches; very dark grayish brown (10YR 3/2) cobbly silt loam, very dark brown (10YR 2/2) moist; few prominent brownish yellow (10YR 6/6) dry relict mottles; weak coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; few very fine and fine dendritic tubular pores; 10 percent gravel and 15 percent cobbles; slightly acid (pH 6.2); clear smooth boundary. (5 to 12 inches thick)

Bw1--7 to 16 inches; brown (10YR 4/3) very cobbly loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; many very fine and fine dendritic tubular pores; 25 percent gravel and 25 percent cobbles; slightly acid (pH 6.4); clear smooth boundary.

Bw2--16 to 27 inches; pale brown (10YR 6/3) very gravelly loam, brown (10YR 5/3) moist; moderate fine subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; few very fine and fine dendritic tubular pores; 35 percent gravel and 10 percent cobbles; neutral (pH 7.0); clear smooth boundary. (combined thickness of Bw1, Bw2 horizons - 15 to 25 inches)

C--27 to 34 inches; light gray (10YR 7/2) very gravelly sandy loam, pale brown (10YR 6/3) moist; common prominent brownish yellow (10YR 6/6) dry redox concentrations; massive; soft, friable, nonsticky and nonplastic; 40 percent gravel and 15 percent cobbles; neutral (pH 7.2); gradual wavy boundary. (5 to 10 inches thick)

2C--34 to 60 inches; light gray (10YR 7/2) extremely gravelly sand, pale brown (10YR 6/3) moist; many prominent brownish yellow (10YR 6/6) dry redox concentrations; single grain; loose, nonsticky and nonplastic; 55 percent gravel and 15 percent cobbles; neutral (pH 7.2).

TYPE LOCATION: Beaverhead County, Montana; approximately 900 feet east and 2,300 feet north of the southwest corner of sec. 6, T. 4S, R. 16 W; Isaac Meadow topographic quadrangle; Latitude 45 degrees 30 minutes 46.3 seconds N. and Longitude 113 degrees 38 minutes 1.5 seconds W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 35 to 40 degrees F.
Soil moisture control section - dry in some or all parts for 90 or more cumulative days in normal years; not dry in all parts for more than half of the cumulative days
Mollic epipedon thickness - 7 to 15 inches
Depth to sandy-skeletal material - 20 to 40 inches
Depth to seasonal high water table - 24 to 42 inches

A horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 to 3; dry or moist
Clay content: 15 to 27 percent
Rock fragments: 15 to 35 percent--5 to 20 percent gravel, 5 to 20 percent cobbles
Reaction: pH 6.1 to 7.3

Bw1, Bw2 horizons
Hue: 10YR or 2.5Y; dry or moist
Value: 4 to 6 dry; 3 to 6 moist
Chroma: 2 or 3; dry or moist
Texture: sandy loam or loam
Clay content: 15 to 27 percent
Rock fragments: 35 to 60 percent--25 to 40 percent gravel, 10 to 25 percent cobbles
Reaction: pH 6.1 to 7.3

C horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 or 3; dry or moist
Clay content: 10 to 18 percent
Rock Fragments: 35 to 60 percent--30 to 45 percent gravel, 5 to 15 percent cobbles
Reaction: pH 6.6 to 7.3

2C horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 or 3; dry or moist
Texture: loamy sand, sand or coarse sand
Clay content: 0 to 10 percent
Rock Fragments: 35 to 70 percent--30 to 55 percent gravel, 5 to 15 percent cobbles
Reaction: pH 6.6 to 7.3

COMPETING SERIES:
Becks (CO) - are slightly or moderately alkaline throughout
Corralval (CA) - have a xeric soil moisture regime
Wishard (MT) - have an udic soil moisture regime

GEOGRAPHIC SETTING:
Landform - outwash plains, outwash fans, stream terraces, fan remnants, drainageways and landslides
Elevation - 6,000 to 8,000 feet
Slope - 0 to 15 percent
Parent material - alluvium, outwash and slide deposits derived from mixed sources
Climate - long, cold winters; cool, moist springs; short, cool summers
Mean annual precipitation - 14 to 20 inches
Mean annual air temperature - 34 to 39 degrees F.
Frost-free period - 30 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Shewag and Redfish soils. The Shewag soils are 10 to 20 inches deep to sand and gravel and are in more convex positions. The Redfish soils are very poorly drained and are in more concave positions.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderate permeability above the 2C horizon and rapid in the 2C horizon.

USE AND VEGETATION: Slagamelt soils are used for pasture and wildlife habitat. The vegetation is mainly quaking aspen, tufted hairgrass and forbs.

DISTRIBUTION AND EXTENT: Slagamelt soils are not extensive in southwestern Montana. MLRAs - 43B, 44B.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.

SERIES ESTABLISHED: Beaverhead County, Montana, Big Hole Valley Area, 2005.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 1 to 16 inches (A, Bw1 horizons)
Cambic horizon - from 16 to 27 inches (Bw2 horizon)
Redox concentrations - from 27 to 60 inches (C1, C2 horizons)
Particle-size control section - from 11 to 41 inches (part of Bw1, Bw2, C, part of 2C horizons)

Slagamelt soils have a cryic temperature regime, an ustic moisture regime, and an aquic moisture subclass.

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National Cooperative Soil Survey
U.S.A.