LOCATION FOURMILE CO MT WY
Established Series
Rev. GB/LC/TWH
03/2011
FOURMILE SERIES
The Fourmile series consists of very deep, well drained soils that formed in alluvium, outwash, and slope alluvium derived mainly from granite. Fourmile soils are on remnant pediments, stream terraces, alluvial fans, outwash plains, and eskers. These soils have slopes of 2 to 25 percent. The mean annual precipitation is about 15 inches and the mean annual temperature is about 38 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Ustic Argicryolls
TYPICAL PEDON: Fourmile gravelly coarse sandy loam, in grassland. (Colors are for dry soil unless otherwise noted).
A1--0 to 5 inches; dark grayish brown (10YR 4/2) gravelly coarse sandy loam, very dark brown (10YR 2/2) moist; strong fine granular structure; soft, very friable, nonsticky, nonplastic; 15 percent fine and very fine angular gravel; neutral (pH 6.6); clear smooth boundary.
A2--5 to 9 inches; dark grayish brown (10YR 4/2) very gravelly coarse sandy loam, very dark brown (10YR 2/2) moist; weak coarse subangular blocky structure parting to medium granular; slightly hard, very friable, nonsticky, nonplastic; 59 percent fine and very fine angular gravel; neutral (pH 6.6); clear smooth boundary. (combined thickness of the A horizons: 7 to 10 inches thick)
Bt1--9 to 20 inches; brown (7.5YR 5/3) very gravelly sandy clay loam, brown (7.5YR 4/3) moist; moderate coarse prismatic structure parting to coarse subangular blocky; slightly hard, very friable, slightly sticky, slightly plastic; many faint clay films on faces of peds and lining pores; 59 percent fine and very fine angular gravel; neutral (pH 6.6); clear smooth boundary.
Bt2--20 to 24 inches; brown (7.5YR 5/3) very gravelly coarse sandy loam, brown (7.5YR 4/3) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; few faint clay films on faces of peds and lining pores; 59 percent fine and very fine angular gravel; neutral (pH 6.8); gradual wavy boundary. (combined thickness of the Bt horizons: 10 to 30 inches thick)
2C--24 to 60 inches; brown (7.5YR 5/3) very gravelly coarse sand, brown (7.5YR 4/3) moist; single grain; soft, loose, nonsticky, nonplastic; ; 55 percent gravel; neutral (pH 6.8).
TYPE LOCATION: Teller County, Colorado; approximately 2.5 miles south of the village of Florissant; about 2,200 feet north and 2,000 feet west of the southeast corner of sec. 24, T. 13 S., R. 71 W.; Lake George USGS quad; lat. 38 degrees 54 minutes 19 seconds N. and long. 105 degrees 16 minutes 52 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is usually moist in some part during late spring and early fall, and intermittently dry in late fall. Typic Ustic moisture regime.
Mean annual soil temperature: 36 to 44 degrees F.
Mean summer soil temperature: 50 to 58 degrees F.
Thickness of the mollic epipedon: 7 to 10 inches
Depth to argillic horizon: 7 to 10 inches
Depth to lithologic discontinuity: 13 to 45 inches
Depth to the base of the argillic horizon: 15 to 50 inches
Particle-size control section (weighted averages):
Clay content: 20 to 35 percent
Rock fragment content: 35 to 60 percent
A horizons:
Hue: 2.5Y through 7.5YR
Value: 3 through 5 dry , 2 or 3 moist
Chroma: 1 through 3
Texture: very gravelly coarse sandy loam, gravelly coarse sandy loam, gravelly loam, cobbly loam, very cobbly loam
Clay content: 7 to 18 percent
Rock fragment content: 15 to 75 percent
Reaction: moderately acid through slightly alkaline
Bt horizons:
Hue: 2.5Y through 7.5YR
Value: 5 or 6 dry, 4 through 6 moist
Chroma: 2 through 6
Texture: very gravelly sandy clay loam, very gravelly sandy loam, very gravelly coarse sandy loam
Clay content: 18 to 35 percent
Silt: 5 to 40 percent
Sand: 40 to 75 percent with more than 35 percent being fine or coarser sand, a high proportion of medium and coarse sand
Rock fragment content: 35 to 60 percent
Reaction: moderately acid through slightly alkaline
Some pedons have a BC horizon.
2C horizon (includes a 2BC in some pedons):
Hue: 10YR, 7.5YR
Value: 5 or 6 dry, 4 through 6 moist
Chroma: 2 through 6
Texture: extremely gravelly coarse sand, extremely gravelly loamy coarse sand, very gravelly coarse sand, very gravelly loamy coarse sand
Clay content: 3 to 10 percent
Rock fragment content: 35 to 90 percent, (mainly fine and medium gravel with up to 10 percent cobble)
Reaction: slightly acid to neutral
COMPETING SERIES: These are the
Bassel,
Blaine,
Bowen,
Fingerrock,
Fornor,
Geertsen,
Hoodle,
Hungryhill,
Lagarita,
Lambe,
Libeg,
Nathale,
Nathrop,
Norriston,
Quander,
Ratiopeak,
Silverheels,
Spanpeak, and
Woodhall series.
Bassel and
Geertsen soils are deep to a lithic contact.
Blaine,
Bowen,
Hungryhill,
Nathale,
Nathrop, and
Woodhall soils are moderately deep to a lithic contact.
Fingerrock,
Libeg,
Quander,
Silverheels, and
Spanpeak soils do not have a lithologic discontinuity.
Fornor,
Hoodle,
Lagarita,
Lambe, and
Ratiopeak soils have secondary carbonates.
Norriston soils have less than 18 percent clay in the argillic horzon.
GEOGRAPHIC SETTING:
Parent material: moderately thin, noncalcareous, moderately coarse to moderately fine textured alluvium, outwash, and slope alluvium derived principally from granite
Landform: stream terraces, alluvial fans, outwash plains, eskers, and remnant pediments
Slopes: 2 to 25 percent
Elevation: 8,000 to 8,800 feet; in Montana is 6,200 to 7,000 feet
Mean annual temperature: 37 to 40 degrees F.; mean summer temperature is about 57 degrees F.
Mean annual precipitation: 14 to 18 inches
Precipitation pattern: peak periods of precipitation in the spring and early summer
Frost-free period: 50 to 80 days; in Montana 30 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Florissant and
Lymaning soils. Florissant soils are shallow to bedrock. Lymaning soils are moderately deep to bedrock.
DRAINAGE AND PERMEABILITY: Well to somewhat excessively drained; moderately slow through moderate permeability
USE AND VEGETATION: These soils are used for livestock grazing. Native vegetation consists mainly of Arizona fescue, Parry's oatgrass, mountain muhly, slimstem muhly, blue grama, western wheatgrass, and prairie junegrass.
DISTRIBUTION AND EXTENT: Central Colorado, Montana, and Wyoming; LRR E, MLRA 48A, 43B; small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Bighorn National Forest, Wyoming, 1982. The type location is in the Teller-Park soil survey, Teller County, Colorado, where this series was proposed in 1943. The name is from a creek.
REMARKS:
Diagnostic horizons and freatures recongnized in this pedon are:
Series control section: The zone from 0 to 60 inches.
Particle-size control section: The zone from 9 to 24 inches. (Bt1, Bt2 horizons)
Mollic epipedon: The zone from 0 to 9 inches. (A1, A2 horizons)
Argillic horizon: The zone from 9 to 24 inches. (Bt1, Bt2 horizons)
Lithologic discontinuity: The zone from 24 to 60 inches. (2C horizon)
Cryic temperature regime.
National Cooperative Soil Survey
U.S.A.