LOCATION MOOSEFLAT MT+ID
Established Series
Rev. TJK-CBR
10/2026
MOOSEFLAT SERIES
The Mooseflat series consists of very deep, very poorly drained soils that formed in alluvium. These soils are on flood plains, stream terraces, drainageways, depressions and mountain bases. Slopes are 0 to 8 percent. Mean annual precipitation is about 430 mm, and mean annual air temperature is about 3.3 degrees C.
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive Typic Cryaquolls
TYPICAL PEDON: Mooseflat loam, in pasture (colors are for moist soil unless otherwise noted).
Oe--0 to 5 cm; black (10YR 2/1) moderately decomposed plant material, very dark grayish brown (10YR 3/2) dry; neutral (pH 6.8); clear smooth boundary.
A--5 to 25 cm; black (10YR 2/1) loam, gray (10YR 5/1) dry; many fine prominent yellowish brown (10YR 5/6) redox concentrations; moderate medium granular structure; slightly hard, friable, slightly sticky and moderately plastic; many very fine and fine roots; many very fine and fine pores; neutral (pH 7.2); clear smooth boundary.
Bg--25 to 46 cm; very dark gray (10YR 3/1) silt loam, gray (10YR 5/1) dry; common fine prominent dark yellowish brown (10YR 4/6) redox concentrations; weak thin platy structure; hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; common very fine pores; neutral (pH 6.8); abrupt smooth boundary.
2BCg--46 to 56 cm; dark gray (10YR 4/1) loamy fine sand, light gray (10YR 7/1) dry; common fine distinct yellowish brown (10YR 5/4) redox concentrations; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; few fine roots; 5 percent gravel; neutral (pH 6.8); abrupt smooth boundary.
2Cg--56 to 150 cm; gray (10YR 5/1) extremely cobbly loamy sand, gray (10YR 6/1) dry; single grain; loose, nonsticky and nonplastic; 25 percent gravel and 35 percent cobbles; neutral (pH 7.2).
TYPE LOCATION: Jefferson County, Montana; 1,600 feet east and 1,700 feet south of the NW corner of sec. 22, T. 6N, R. 6W. [RC-NIFI1.1]
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--1.7 to 5.6 degrees C.
Thickness of mollic epipedon--25 to 48 cm
Depth to redoximorphic features--5 to 30 cm
Depth to seasonal high water table--0 to 30 cm during the months of April to June
Depth to lithologic discontinuity--36 to 66 cm
Particle-size control section (weighted averages)
Clay content--18 to 27 percent in the upper part, 2 to 10 percent in the lower part
Total rock fragments--5 to 15 percent in the upper part, 50 to 65 percent in the lower part
Note--some pedons may have a Bw, 2Bw and/or Cg horizon
Oe horizon (when present)
Thickness--0 to 10 cm
A horizon
Hue--10YR to 5Y dry or moist
Value--4 or 5 dry, 2 or 3 moist
Chroma--1 or 2 dry or moist
Texture (less than 2 mm fraction)--loam, silty clay loam, silt loam
Clay content--15 to 35 percent
Rock fragments--0 to 10 percent--0 to 12 percent gravel, 0 to 5 percent cobbles
Reaction--pH 5.6 to 7.3
Thickness--15 to 38 cm
Bg horizon
Hue--10YR to 5Y dry or moist
Value--4 to 6 dry, 2 to 5 moist
Chroma--1 or 2 dry or moist
Texture (less than 2 mm fraction)--sandy loam, loam, silt loam or silty clay loam
Clay content--15 to 35 percent
Rock fragments--0 to 20 percent--0 to 15 percent gravel, 0 to 5 percent cobbles
Reaction--pH 6.1 to 7.8
Thickness--0 to 30 cm
2BCg horizon (when present)
Hue--10YR, 2.5Y or 5Y; dry or moist
Value--6 or 7 dry; 4 or 5 moist
Chroma--1 or 2; dry or moist
Texture (less than 2 mm fraction)--sandy loam, fine sandy loam or loamy fine sand
Clay content--10 to 18 percent
Rock fragments--5 to 20 percent--5 to 15 percent gravel, 0 to 5 percent cobbles
Reaction--pH 6.1 to 7.8
Thickness--0 to 15 cm
2Cg horizon
Hue--10YR or 2.5Y; dry or moist
Value--5 to 7 dry; 4 to 6 moist
Chroma--1 to 3; dry or moist
Texture--sand, loamy sand, coarse sand or loamy coarse sand
Clay content--0 to 12 percent
Rock fragments--35 to 70 percent--20 to 35 percent gravel, 10 to 50 percent cobbles and stones
Reaction--pH 5.6 to 7.8
COMPETING SERIES:
Foxcreek (ID)--soils have secondary calcium carbonate accumulation
Walden (CO)-- soils have a calcic horizon
GEOGRAPHIC SETTING:
Landform--flood plains, stream terraces, drainageways, depressions, and mountain bases
Elevation--1,585 to 2,550 meters
Slope--0 to 8 percent. (Slopes are as high as 50 percent in seeped areas of mountains.)
Parent material--alluvium
Climate--long, cold winters; cool moist springs; short, cool summers
Mean annual precipitation--380 to 1,130 [RC-NIFI2.1]mm
Mean annual air temperature--0.6 to 4.4 degrees C.
Frost-free period--30 to 70 days
Flooding--none to frequent
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Very poorly drained; 5 to 25 um/sec in the upper part and 50 to 200 um/sec in the lower part.
USE AND VEGETATION: Mooseflat soils are primarily used for grazing and wildlife habitat. The potential native vegetation is mainly northern reedgrass, bluejoint reedgrass, American mannagrass, tufted hairgrass, mountain alder, tall sedges and willows.
DISTRIBUTION AND EXTENT: Mooseflat soils are of small extent in southwestern Montana and southeastern Idaho; MLRAs 43B, 44B, 47.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Gallatin County, Montana, 1997; proposed Jefferson County, Montana, 1994.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon--5 to 46 cm (A, Bg horizons)
Lithologic discontinuity--46 cm (2BCg horizon)
Strongly contrasting particle-size class--between the fine-loamy Bg horizon and the sandy 2BCg horizon
Redoximorphic concentrations--5 to 56 cm (A, Bg, 2BCg horizons)
Depleted matrix--25 to 150 cm (Bg, 2BCg, 2Cg horizons)
Particle-size control section--30 to 107 cm (part of Bg, BCg, part of 2Cg horizons)
Mooseflat soils have a cryic temperature regime and an aquic moisture regime.
Taxonomic version: Twelfth Edition, 2014
National Cooperative Soil Survey
U.S.A.