LOCATION LEFTFORK IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Argixerolls
TYPICAL PEDON: Leftfork loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 5 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate coarse subangular blocky structure parting to strong medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine tubular and interstitial pores; 1 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (4 to 8 inches thick)
Bt1--5 to 11 inches; brown (10YR 4/3) clay, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; very hard, very firm, very sticky and very plastic; many very fine and common fine, medium and coarse roots; many very fine and fine tubular and interstitial pores; common faint clay films on faces of peds and in pores; 1 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (5 to 10 inches thick)
Bt2--11 to 18 inches; brown (7.5YR 4/4) clay, dark brown (7.5YR 3/4) moist; strong coarse prismatic structure parting to weak fine subangular blocky; hard, very firm, very sticky and very plastic; common very fine and fine roots; common very fine and fine tubular and interstitial pores; common faint clay films on faces of peds and in pores; 5 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (5 to 15 inches thick)
Bt3--18 to 25 inches; strong brown (7.5YR 4/6) clay, brown (7.5YR 4/4) moist; strong medium prismatic structure parting to moderate medium subangular blocky; hard, very firm, very sticky and very plastic; common very fine and fine roots; common very fine and fine tubular and interstitial pores; common faint clay films on faces of peds and in pores; 10 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (5 to 20 inches thick)
2Bt4--25 to 43 inches; brown (7.5YR 5/4) extremely stony clay, brown (7.5YR 4/4) moist; weak coarse subangular blocky structure; hard, very firm, very sticky and very plastic; few very fine and fine roots; few very fine and fine tubular pores; common faint clay films on faces of peds and in pores; 45 percent gravel, 15 percent cobbles and 15 percent stones; strongly effervescent; neutral (pH 7.2); clear wavy boundary. (0 to 20 inches thick)
2Cr--43 to 45 inches; grayish brown (2.5Y 5/2) weathered limestone; violently effervescent. (0 to 5 inches thick)
2R--45 inches; limestone.
TYPE LOCATION: Bear Lake County, Idaho; about 2 miles southwest of Fish Haven; 600 feet south and 300 feet east of the northwest corner of section 21, T. 16 S., R. 43 E.; USGS St. Charles 7.5 minute topographic quadrangle; 42 degrees, 01 minutes, 44 seconds north latitude and 111 degrees, 26 minutes, 28 seconds west longitude, NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture control section - usually moist, dry in all parts for 45 consecutive days or more in the four months following the summer solstice. Xeric moisture regime.
Mollic epipedon thickness - 7 to 14 inches.
Depth to bedrock - 40 to 60 inches.
Average annual soil temperature - 42 to 46 degrees F. Frigid soil temperature regime.
A horizon
Hue - 10YR to 5YR
Value - 3 to 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture - loam
Clay content - 18 to 25 percent
Rock fragments - 0 to 10 percent gravel
Reaction - slightly acid
AB or BA horizons may be present in some pedons
Bt horizons
Hue - 10YR to 5YR
Value - 4 or 5 dry, 3 or 4 moist
Chroma - 3 to 6 dry, 3 or 4 moist
Texture - clay, silty clay, clay loam or silty clay loam
Clay content - 32 to 47 percent (averages greater than 35 percent)
Rock fragments - 1 to 14 percent gravel, and 0 to 2 percent cobbles or stones in lower part
Reaction - slightly acid
2Bt horizon (when present)
Hue - 10YR to 5YR
Value - 4 or 5 dry or moist
Chroma - 4 or 5 dry or moist
Texture - clay, silty clay, clay loam or silty clay loam
Clay content - 32 to 49 percent (averages greater than 35 percent)
Rock fragments - 25 to 60 percent gravel, 10 to 20 percent cobbles, 10 to 20 percent stones
Reaction - neutral or slightly alkaline
COMPETING SERIES: These are the Beefhollow, Booford, Harter, Manila, Marsden, Observation, Ostler, Rob Roy, Shagnasty and Tatouche series. Booford, Observation and Rob Roy soils are moderately deep to bedrock. Beefhollow, Harter, Manila, Ostler and Tatouche soils are greater than 60 inches to bedrock. Marsden soils have less than 30 day frost-free period and formed in lacustrine sediments. Shagnasty soils formed in rhyolite, andesite or quartzite.
GEOGRAPHIC SETTING:
Landform: mountain sideslopes and ridgetops
Elevation: 5,800 to 7,100 feet
Slope: 5 to 40 percent
Parent material: alluvium from sedimentary rocks
Climate: long, cold winters; moist springs; warm, dry summers
Average annual precipitation: 12 to 20 inches
Average annual temperature: 39 to 45 degrees F.
Frost-free season: 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cleavage, Shalcleav and Swanpeak soils. Cleavage and Shalcleav soils are shallow to bedrock and occur on similar landform positions. Swanpeak soils have clayey-skeletal particle-size control sections and occur on slightly lower landscape positions and on summit flats.
DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; slow permeability.
USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. The present vegetation is mainly mountain big sage, low sage, antelope bitterbrush, service berry, buckwheat, Kentucky bluegrass and bigtop bluegrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Bear Lake County, Idaho, 2008. The name is from a nearby spring and canyon.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface of the soil to a depth of 11 inches (A and Bt1 horizons).
Argillic horizon - the zone from 5 to 43 inches. (Bt1, Bt2, Bt3 and 2Bt4 horizons).