LOCATION MOLLET MT
Established Series
Rev. ADI-BDD-EMM
05/2013
MOLLET SERIES
The Mollet series consists of very deep, well drained soils that formed in alluvium and colluvium derived from fine grained igneous rocks. These soils are on alluvial fans, stream terraces, hills, and mountains. Slopes are 2 to 60 percent. Mean annual precipitation is about 21 inches, and mean annual temperature is about 37 degrees F.
TAXONOMIC CLASS: Fine, mixed, superactive Ustic Argicryolls
TYPICAL PEDON: Mollet loam, 4 to 15 percent slopes, in rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 7 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak fine granular structure; slightly hard, very friable, nonsticky and nonplastic; many very fine, common fine, and few medium roots; many very fine and fine irregular pores; 5 percent gravel; moderately acid (pH 5.6); clear wavy boundary.
A2--7 to 12 inches; grayish brown (10YR 5/2) loam, very dark brown (10YR 2/2) moist; weak very fine subangular blocky structure; hard, friable, nonsticky and nonplastic; many very fine, common fine, and few medium roots; few very fine and fine tubular pores; 10 percent gravel; moderately acid (pH 5.8); abrupt wavy boundary. (Combined thickness of the A horizons is 7 to 16 inches.)
Bt1--12 to 16 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine, few fine and medium roots; common very fine and fine tubular pores; common distinct clay films on faces of peds; 10 percent gravel; moderately acid (pH 6.0); abrupt smooth boundary.
Bt2--16 to 29 inches; light yellowish brown (10YR 6/4) gravelly clay loam, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and moderately plastic; common very fine, few fine and medium roots; common very fine, few fine and medium tubular pores; common distinct clay films on faces of peds; 10 percent gravel and 5 percent cobbles; moderately acid (pH 6.0); abrupt wavy boundary. (Combined thickness of Bt horizons is 10 to 26 inches thick)
Bt3--29 to 60 inches; light yellowish brown (10YR 6/4) gravelly clay loam, dark yellowish brown (10YR 4/4) moist; strong medium subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; few very fine and fine roots; common very fine, few fine and medium tubular pores; few faint clay films on faces of peds; 10 percent gravel and 5 percent cobbles; moderately acid (pH 6.0); abrupt wavy boundary.
TYPE LOCATION: Powell County, Montana; 1,100 feet south and 800 feet east of the NW corner of sec. 11, T. 10 N., R. 6 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 36 to 41 degrees F.
Moisture control section - between 4 to 12 inches.
Mollic epipedon thickness - 10 to 16 inches.
Control section - 35 to 50 percent clay.
Rock fragments - 0 to 35 percent.
A horizons
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2, dry or moist
Clay content: 20 to 27 percent
Rock fragments: 0 to 35 percent--0 to 10 percent stones or boulders, 0 to 15 percent cobbles, 0 to 20 percent gravel
Reaction: pH 5.6 to 7.3
Bt1 horizon
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 2 or 3, dry or moist
Texture: clay loam, silty clay loam, or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent gravel
Reaction: pH 5.6 to 7.8
Bt2 horizon
Texture: clay loam, clay, or silty clay loam
Clay content: 35 to 50 percent
Rock fragments: 5 to 25 percent--0 to 5 percent cobbles, 5 to 10 percent gravel
Reaction: pH 5.6 to 7.8
Bt3 horizon
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 to 6, dry or moist
Texture: clay loam or clay
Clay content: 35 to 45 percent
Rock fragments: 15 to 35 percent--5 to 10 percent cobbles, 10 to 25 percent gravel
Reaction: pH 5.6 to 7.8
COMPETING SERIES:
Bangtail (MT) - has a paralithic contact at 20 to 40 inches.
Bridger (MT) - has a horizon of calcium carbonate accumulation.
Duckcreek (MT) - has horizon of secondary carbonate accumulation.
Echard (UT) - developed in volcanic ash materials of weakly cemented ash and soft tuff.
Melville (MT) - has horizon of secondary carbonate accumulation.
Rattler (MT) - has a horizon of calcium carbonate accumulation.
Sevier (UT) - has bedrock at depths of 20 to 40 inches.
GEOGRAPHIC SETTING:
Landform - alluvial fans; stream terraces; hills; mountains.
Elevation - 5,200 to 7,800 feet.
Slope - 2 to 60 percent.
Parent material - colluvium and alluvium derived from fine grained igneous rocks.
Climate - long, cold winters; moist springs; short summers.
Mean annual precipitation - 15 to 23 inches.
Mean annual air temperature - 34 to 39 degrees F.
Frost-free season - 30 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: none listed.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Mollet soils are used mainly for rangeland. Native vegetation is mainly rough fescue, needlegrass, mountain brome, Idaho fescue, and tufted hairgrass.
DISTRIBUTION AND EXTENT: Mollet soils are moderately extensive in southwestern Montana. MLRA 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Powell County, Montana, 1994.
REMARKS: Soil interpretation record: MT1299, MT1300.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from the surface to 12 inches (A1, A2 horizons)
Argillic horizon - from 12 to 60 inches (Bt1, Bt2, Bt3 horizons)
Mollet soils have a cryic temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.