LOCATION FRENCHCREEK MT+CO
Established Series
Rev. LCB-DRS-EMM
11/2012
FRENCHCREEK SERIES
The Frenchcreek series consists of very deep, well drained soils that formed in gravelly alluvium. These soils are on alluvial fans and stream terraces. Slopes are 2 to 20 percent. The mean annual precipitation is about 12 inches, and the mean annual temperature is about 43 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Aridic Haplustolls
TYPICAL PEDON: Frenchcreek very gravelly loam, in grassland (colors are for dry soil unless otherwise noted).
A--0 to 5 inches; grayish brown (10YR 5/2) very gravelly loam, very dark grayish brown (10YR 3/3) moist; moderate very thin platy structure parting to moderate very fine granular; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; 55 percent angular gravel; slightly acid (pH 6.1); clear smooth boundary. (4 to 15 inches thick).
Bw1--5 to 12 inches; brown (10YR 5/3) very gravelly loam, dark brown (10YR 4/3) moist; weak medium and fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular and interstitial pores; 60 percent angular gravel; slightly acid (pH 6.2); gradual smooth boundary. (5 to 15 inches thick).
Bw2--12 to 26 inches; pale brown (10YR 6/3) extremely gravelly sandy loam, dark brown (10YR 4/3) moist; weak very fine granular structure; soft, very friable, slightly sticky and nonplastic; common very fine roots; 70 percent angular gravel; slightly acid (pH 6.4); gradual smooth boundary. (10 to 20 inches thick)
C1--26 to 36 inches; pale brown (10YR 6/3) extremely gravelly loamy sand, dark brown (10YR 4/3) moist; single grain; loose; slightly sticky and nonplastic; few very fine roots; 80 percent angular gravel; neutral (pH 6.6); gradual smooth boundary. (0 to 12 inches thick)
C2--36 to 60 inches; very pale brown (10YR 7/4) extremely gravelly loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, friable, sticky and slightly plastic; 70 percent angular gravel; neutral (pH 6.8).
TYPE LOCATION: Lewis and Clark County, Montana; 800 feet east and 2,000 feet north of SE corner of sec. 29, T. 13 N., R. 3 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 8 to 24 inches.
Mollic epipedon thickness - 7 to 15 inches, may or may not include part of the Bw horizon.
A horizon
Hue: 5YR, 7.5R, or 10YR
Value: 4 or 5 dry, 3 moist
Chroma: 2 or 3, dry or moist
Texture: loam or sandy loam
Clay content: 15 to 25 percent
Rock fragments: 15 to 70 percent total--0 to 15 percent stones and cobbles; 15 to 55 percent angular gravel
Reaction: pH 6.1 to 7.8
Bw1 horizon
Hue: 5YR, 7.5YR, or 10YR
Value: 4, 5, or 6 dry; 3 or 4 moist
Chroma: 3 or 4, dry or moist
Texture: loam or sandy loam
Clay content: 15 to 25 percent
Rock fragments: 30 to 80 percent total--0 to 15 percent stones and cobbles, 30 to 65 percent angular gravel
Reaction: pH 6.1 to 7.8
Bw2 horizon
Hue: 5YR, 7.5YR, or 10YR
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: sandy loam or loam
Clay content: 10 to 20 percent
Rock fragments: 35 to 75 percent total--0 to 5 percent cobbles, 35 to 70 percent angular gravel
Reaction: pH 6.1 to 7.8
C1 horizon
Hue: 5YR, 7.5Y, or 10YR
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: loamy sand or sandy loam
Clay content: 5 to 15 percent
Rock fragments: 50 to 80 percent total--0 to 5 percent cobbles, 50 to 75 percent angular gravel
Reaction: pH 6.1 to 7.8
C2 horizon
Hue: 5YR, 7.5YR, or 10YR
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2, 3, or 4
Texture: loam or sandy loam
Clay content: 10 to 20 percent
Rock fragments: 60 to 80 percent total--0 to 5 percent angular cobbles, 60 to 75 percent angular gravel
Reaction: pH 6.6 to 7.8
COMPETING SERIES:
Bulltop (ND) - has a horizon of secondary carbonate accumulation.
Dolus (MT) - has a horizon of secondary carbonates and a paralithic contact of semiconsolidated sandstone at depths of 20 to 40 inches.
Owenfort (MT) - does not have a cambic horizon.
Sixbeacon (MT) - has horizons of secondary carbonates and a discontinuity at depths of 10 to 40 inches; has a calcic horizon.
GEOGRAPHIC SETTING:
Landform - stream terraces, alluvial fans.
Elevations - 3,800 to 5,000 feet. In Colorado elevations range as high as 8,800 feet.
Slopes - 2 to 20 percent.
Parent material - gravelly alluvium from mixed rock sources.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches. In Colorado precipitation is as high as 16 inches.
Mean annual temperature - 40 to 45 degrees F.
Frost-free period - 70 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability.
USE AND VEGETATION: Frenchcreek soils are used mainly for rangeland. Potential native vegetation is mainly bluebunch wheatgrass, needleandthread, Sandberg bluegrass, western wheatgrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: The series is not extensive in Southwestern Montana. MLRAs 44B, 46 and 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Colorado, 1984. Proposed in Lewis and Clark County, Montana, 1979.
REMARKS: Soil interpretation record: MT0376, MT0088, MT0503.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the soil surface to 7 inches (mixed)(A, Bw1 horizons)
Cambic horizon - the zone from 5 to 26 inches (Bw1, Bw2 horizons)
Particle-size control section - the zone from 10 to 40 inches (Bw1, Bw2, C1, C2 horizons)
Frenchcreek soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.
National Cooperative Soil Survey
U.S.A.