LOCATION PERMA MT+CO UT WY
Established Series
Rev. BDD-DES-RJS
11/2012
PERMA SERIES
The Perma series consists of very deep, somewhat excessively drained soils that formed in alluvium, colluvium and outwash. These soils are on stream terraces, outwash terraces, outwash plains, inset fans, alluvial fans, fan remnants, eroded fan remnants, escarpments, moraines, hills and mountains. Slopes are 0 to 80 percent. Mean annual precipitation is about 430 mm, and mean annual air temperature is about 6.0 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Haplustolls
TYPICAL PEDON: Perma gravelly loam, in grassland (colors are for dry soil unless otherwise noted).
A1--0 to 15 cm; dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; common very fine and fine pores; 20 percent gravel; neutral (pH 7.0); clear wavy boundary.
A2--15 to 30 cm; dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; common very fine and fine pores; 30 percent gravel; neutral (pH 7.2); clear wavy boundary. (combined thickness of A horizons - 18 to 38 cm)
Bw1--30 to 55 cm; brown (10YR 5/3) very gravelly loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and fine roots; common very fine pores; 35 percent gravel and 15 percent cobbles; neutral (pH 7.2); gradual wavy boundary.
Bw2--55 to 91 cm; pale brown (10YR 6/3) very gravelly sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; common very fine pores; 40 percent gravel and 15 percent cobbles; slightly alkaline (pH 7.4); gradual wavy boundary. (combined thickness of Bw horizons - 16 to 90 cm)
BC--91 to 152 cm; very pale brown (10YR 7/3) extremely gravelly loamy sand, grayish brown (10YR 5/2) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; 50 percent gravel and 20 percent cobbles; slightly alkaline (pH 7.4).
TYPE LOCATION: Missoula County, Montana; 460 meters east and 90 meters north of the SW corner of sec. 19, T. 14N, R.15W.
RANGE IN CHARACTERISTICS:
Soil temperature - 3.5 to 8.0 degrees C.
Mollic epipedon thickness - 25 to 38 cm
Depth to extremely gravelly material - 75 to 96 cm
Note: Below a depth of 100 cm the rock fragments may have calcium carbonate casts on their undersides.
A horizons
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: loam or sandy loam
Clay content: 7 to 27 percent
Rock fragments: 5 to 60 percent--5 to 50 percent gravel, 0 to 30 percent cobbles, stones and boulders
Reaction: pH 6.1 to 7.4
Bw horizons
Hue: 2.5Y, 10YR or 7.5YR; dry or moist
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 4; dry or moist
Texture: loam or sandy loam
Clay content: 7 to 27 percent
Rock fragments: 35 to 85 percent--25 to 65 percent gravel, 0 to 50 percent cobbles and stones
Reaction: pH 6.1 to 7.8
BC horizon
Hue: 2.5Y, 10YR, 7.5YR or 5YR; dry or moist
Value: 4 to 7 dry; 3 to 5 moist
Chroma: 2 to 4; dry or moist
Texture: loam, coarse sandy loam or sandy loam, loamy sand or sand
Clay content: 0 to 20 percent
Rock fragments: 60 to 85 percent--25 to 65 percent gravel, 10 to 50 percent cobbles and stones
Calcium carbonate equivalent: 0 to 10 percent
Reaction: pH 6.6 to 8.4
COMPETING SERIES:
Aguja (NM) - are moderately deep to a lithic contact
Finleypoint (MT) - have less than 60 percent coarse fragments below 30 inches
Flott (MT) - have a calcic horizon
Kutler (CO) - are moderately deep to a paralithic contact
Labre (MT) - have a calcic horizon
Peso (NM) - are moderately deep to a lithic contact
Pesowyo (WY) - are moderately deep to a lithic contact
Renegade (UT) - are deep to a paralithic contact
Sandia (NM) - are moderately deep to a lithic contact
Slimbutte (SD) - have calcium carbonate accumulation within 100 cm of the surface
Subwell (MT) - have a calcic horizon
Towave (UT) - have calcium carbonate accumulation within 100 cm of the surface
Veatch (CO) - are moderately deep to a lithic contact
Vigilante (MT) - are deep to a lithic contact
Walstead (MT) - have a calcic horizon
Wanagan (ND) - have calcium carbonate accumulation within 100 cm of the surface
Wimper (MT) - have a calcic horizon
GEOGRAPHIC SETTING:
Landform - stream terraces, outwash terraces, outwash plains, inset fans, alluvial fans, fan remnants, eroded fan remnants, escarpments, moraines, hills and mountains
Elevation - 1,025 to 2,400 meters
Slope - 0 to 80 percent
Parent material - alluvium, colluvium and outwash
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 360 to 560 cm
Mean annual air temperature - 2.0 to 7.5 degrees C.
Frost-free period - 70 to 135 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; moderate permeability.
USE AND VEGETATION: Perma soils are used mainly as rangeland. The potential native vegetation is rough fescue, Idaho fescue, bluebunch wheatgrass, prairie junegrass, and native forbs.
DISTRIBUTION AND EXTENT: Perma soils are of moderate extent in western and central Montana. MLRAs - 43A, 43B, 44A, 44B, 46 and 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Mineral County, Montana, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 30 cm (A1, A2 horizons)
Cambic horizon - 30 to 91 cm (Bw1, Bw2 horizons)
Depth to extremely gravelly material - at 91 cm (BC horizon)
Particle-size control section - 25 to 100 cm (part of A2, Bw1, Bw2, part of BC horizons).
Perma soils have a frigid temperature regime and an ustic moisture regime.
ADDITIONAL DATA: Soil interpretation records - MT0117, MT0211 and MT0148.
National Cooperative Soil Survey
U.S.A.