LOCATION CLASOIL MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Clasoil gravelly loam, bouldery in rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 5 inches; very dark grayish brown (10YR 3/2) gravelly loam, black (10YR 2/1) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and few fine and medium roots; many very fine and fine interstitial pores; 5 percent cobbles, 10 percent pebbles; slightly acid (pH 6.2); clear smooth boundary.
A2--5 to 13 inches; dark grayish brown (10YR 4/2) gravelly loam, very dark gray (10YR 3/1) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; many very fine and few fine and medium roots; many very fine and common fine pores; 5 percent cobbles; 25 percent pebbles; slightly acid (pH 6.2); clear smooth boundary. (Combined thickness of A horizons is 4 to 15 inches)
Bt1--13 to 24 inches; light yellowish brown (10YR 6/4) gravelly sandy clay loam, yellowish brown (10YR 5/4) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, moderately sticky and moderately plastic; common very fine and few fine and medium roots; common very fine and fine pores; common thin clay films on the faces of peds and bridging between sand grains; 5 percent cobbles, 15 percent pebbles; neutral (pH 6.7); clear smooth boundary.
Bt2--24 to 34 inches; light yellowish brown (2.5Y 6/4) cobbly sandy clay loam, yellowish brown (10YR 5/4) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine and few fine and medium roots; common very fine and few fine pores; common thin clay films on faces of peds and bridging between sand grains; 20 percent cobbles, 10 percent pebbles; neutral (pH 6.7); clear smooth boundary. (Combined thickness of Bt horizons is 8 to 24 inches)
BC--34 to 60 inches; light yellowish brown (10YR 6/4) very cobbly loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; 25 percent cobbles, 15 percent pebbles; neutral (pH 6.6).
TYPE LOCATION: Jefferson County, Montana; 500 feet north and 1,000 feet east of the SW corner of sec. 13, T. 9 N., R. 2 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 38 to 46 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 15 inches.
Depth to argillic horizon - 4 to 22 inches.
A horizons - Hue: 10YR or 2.5Y
Value: 2, 3, or 4 dry, 2 or 3 moist
Chroma: 2 or 3
Texture: loam or sandy loam
Clay content: 12 to 20 percent
Rock fragments: 0 to 35 percent--0 to 5 percent stones, 0 to 10 percent cobbles, 0 to 25 percent pebbles
Reaction: pH 5.1 to 7.3
Bt horizons - Hue: 10YR or 2.5Y
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 1, 2, 3, or 4
Texture: sandy clay loam, loam, or clay loam
Clay content: 18 to 30 percent
Rock fragments: 5 to 35 percent--0 to 20 percent stones and cobbles, 5 to 35 percent pebbles
Reaction: pH 5.6 to 7.3
BC horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2, 3, 4, or 6
Texture: sandy loam, loam, or coarse sandy loam
Clay content: 12 to 20 percent
Rock fragments: 15 to 40 percent--0 to 25 percent stones and cobbles, 15 to 35 percent pebbles
Reaction: pH 6.1 to 7.8
COMPETING SERIES:
Absarook (MT) - has a lithic contact at 20 to 40 inches.
Archmesa (CO) has a lithic contact at 20 to 40 inches.
Beartooth (MT) - has calcium carbonate present.
Beeno (WY) - has a paralithic contact between depths of 20 to 40 inches.
Bielenberg (MT) - has a paralithic contact between depths of 40 to 60 inches.
Bookcliff (UT) - has calcium carbonate present.
Burtoner (MT) - has a paralithic contact at 20 to 38 inches.
Clancy (MT) - has a lithic contact above a depth of 60 inches.
Dooley (MT) - has calcium carbonate present.
Doughty (MT) has horizons of secondary carbonate accumulation.
Empedrado (CO) - has calcium carbonate present.
Fairfield (MT) - has calcium carbonate present.
Farnuf (MT) - has calcium carbonate present.
Farside (MT) ustic bordering on udic moisture regime.
Felor (SD) - has calcium carbonate present.
Greenway (SD) - has calcium carbonate present.
Gurney (SD) - has a lithic contact between depths of 20 to 40 inches.
Hangdo (UT) - has hues redder than 10YR throughout the profile; has pHs that are mildly to moderately alkaline.
Hoppers (MT) - has a lithic contact at 20 to 40 inches.
Hyalite (MT) - has a lithologic discontinuity in the lower part of the argillic horizon; has a lithologic discontinuity of sandy-skeletal material below the argillic horizon.
Jeffcity (MT) - has a paralithic contact of grus at depths of 20 to 38 inches; has a lithic contact of granite at depths of 23 to 40 inches.
Kokoruda (MT) - has an O horizon.
Livona (ND) - has calcium carbonate present.
Martinsdale (MT) - has calcium carbonate present.
Maudlin (CO) - has a lithic contact between depths of 20 to 40 inches.
Meagher (MT) - have a calcic horizon that is also a lithologic discontinuity.
Moen (CO) - has a lithic contact between depths of 20 to 40 inches.
Moento (CO) has a lithic contact at 20 to 40 inches.
Pianohill (MT) - has a lithic contact of volcanic mudflow breccia at depths of 20 to 40 inches.
Placerton (MT) - has a lithic contact above a depth of 60 inches.
Reeder (ND) - has a paralithic contact between depths of 20 to 40 inches.
Reedwest (MT) - has a paralithic contact at 20 to 40 inches.
Sipple (MT) has horizons of secondary carbonate accumulation.
Snakejohn (UT) - has a lithic contact at 40 to 60 inches.
Sponseller (AZ) - has hues redder than 10YR throughout the profile; has less than 45 percent sand in the argillic horizon.
Trag (CO) has hues as red as 7.5YR.
Tragmon (CO) - has C horizons; formed in material from shale and sandstone at elevations above 7100 feet.
Trazuni (NM) - has redox concentrations at 35 to 50 inches.
Trujillo (CO) has horizons of secondary carbonate accumulation.
Ulrant (WY) - has calcium carbonate present.
Vida (MT) - has horizons of secondary carbonate accumulation.
Watne (MT) - has horizons of secondary carbonate accumulation.
Watrous (ND) - has a lithic contact between depths of 20 to 40 inches.
Williams (ND) - has calcium carbonate present.
Yegen (MT) - has calcium carbonate present.
GEOGRAPHIC SETTING:
Landform - mountains; foothills; alluvial fans; terraces.
Elevation - 3,500 to 6,600 feet.
Slope - 0 to 60 percent.
Parent material - alluvium derived mainly from granite and other coarse grained igneous rocks.
Climate - long, cold winters; moist springs; warm, dry summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual air temperature - 36 to 45 degrees F.
Frost free period - 70 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Sawbuck and Sawicki soils. These soils are loamy-skeletal and are on similar landform positions.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability in the argillic horizon and moderately rapid below.
USE AND VEGETATION: Clasoil soils are primarily used for rangeland and wildlife habitat. The potential native vegetation is Idaho fescue, bluebunch wheatgrass, rough fescue, Sandberg bluegrass, mountain big sagebrush, and rubber rabbitbrush.
DISTRIBUTION AND EXTENT: Clasoil soils are of limited extent in southwestern Montana.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Powell County, Montana, 1995. Series proposed: Jefferson County, Montana, 1993.
REMARKS: Soil interpretation record: MT1531, MT3011. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 13 inches (A1, A2 horizons); an argillic horizon from 13 to 33 inches (Bt1, Bt2 horizons); a particle-size control section from 13 to 34 inches (Bt1, Bt2 horizon). Clasoil soils have a frigid temperature regime and an ustic moisture regime.