LOCATION HALFCIRCLE IDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive Calcic Pachic Argicryolls
TYPICAL PEDON: Halfcircle silt loam, forested, at 6,620 feet elevation. When described on September 7, 1995, the soil was dry throughout. (Colors are for air dry soil unless otherwise noted.)
Oa--0 to 1 inch; highly decomposed organic matter.
A1--1 to 3 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; moderate medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; common very fine irregular and tubular pores; 5 percent channers; slightly alkaline (pH 7.7); clear smooth boundary.
A2--3 to 7 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; moderate medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine, and medium, and few coarse roots; common very fine and few fine tubular pores; 5 percent channers; slightly alkaline (pH 7.8); clear smooth boundary. (Combined thickness of A horizons is 7 to 16 inches.)
Btk--7 to 16 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (2.5Y 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine, and medium, and few coarse roots; common very fine and few fine tubular pores; few patchy faint clay films in root channels and pores; strongly effervescent, few fine rounded carbonate concretions throughout (12 percent calcium carbonate equivalent); 5 percent channers; moderately alkaline (pH 7.9); clear smooth boundary. (9 to 14 inches thick)
Bk--16 to 22 inches; grayish brown (2.5Y 5/2) silt loam, dark grayish brown (2.5Y 4/2) moist; weak medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine, and medium, and few coarse roots; common very fine tubular pores; strongly effervescent, disseminated lime and few fine rounded carbonate concretions throughout (17 percent calcium carbonate equivalent); 5 percent channers; moderately alkaline (pH 8.2); gradual wavy boundary. (3 to 9 inches thick)
C--22 to 42 inches; light gray (2.5Y 7/2) silt loam, light olive brown (2.5Y 5/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; few very fine tubular pores; violently effervescent, disseminated lime (31 percent calcium carbonate equivalent); 5 percent channers; moderately alkaline (pH 8.4); gradual wavy boundary. (10 to 21 inches thick)
Cr--42 inches; calcareous siltstone.
TYPE LOCATION: Bear Lake County, Idaho; about 1 mile northeast of Geneva Summit; about 2,900 feet west and 1,400 feet south of the northeast corner of sec. 31, T.12S., R.46W. Latitude - 42 degrees, 20 minutes, 25 seconds north; Longitude - 111 degrees, 7 minutes, 25 seconds west.
RANGE IN CHARACTERISTICS:
Mollic epipeon thickness - 16 to 30 inches.
Depth to argillic horizon - 7 to 16 inches.
Depth to calcic horizon - 16 to 30 inches.
Depth to paralithic contact - 40 to 60 inches.
Average annual soil temperature - 37 to 42 degrees F.
Particle-size control section:
Clay content average - 24 to 32 percent (total clay).
Rock fragment content range - 0 to 10 percent.
Calcium carbonate equivalent - 5 to 15 percent (less than 2mm plus rock fragments less than 20mm).
A horizons:
Value - 3 through 5 dry, 2 or 3 moist
Chroma - 1 or 2 dry or moist
Reaction - neutral or slightly alkaline
Btk horizon:
Hue - 10YR or 2.5Y
Value - 4 or 5 dry
Chroma - 2 or 3 dry and moist
Texture - silt loam or silty clay loam
Calcium carbonate equivalent - 5 to 15 percent
Reaction - slightly or moderately alkaline
Bk horizon:
Value - 5 or 6 dry, 4 or 5 moist
Chroma - 2 or 3 dry or moist
Calcium carbonate equivalent - 15 to 30 percent
Reaction - moderately alkaline
C horizon:
Hue - 2.5Y or 5Y
Value - 6 or 7 dry, 5 or 6 moist
Chroma - 2 or 3 dry or moist
Calcium carbonate equivalent - 15 to 40 percent
Reaction - moderately alkaline
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Halfcircle soils are on mountains at elevations of 6,300 to 7,850 feet. They are generally on north facing slopes. They formed in loess influenced colluvium over residuum weathered from calcareous siltstone. Slopes are 20 to 70 percent. The average annual precipitation is 16 to 25 inches. The average annual air temperature is 36 to 41 degrees F. The frost free period is 50 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hagenbarth and Preussrange (T) soils. Hagenbarth soils have a fine-loamy particle-size control section and are very deep. They are on hills adjacent to Halfcircle soils. Preussrange soils are generally on south facing slopes and are 20 to 40 inches deep to a paralithic contact.
DRAINAGE AND PERMEABILITY: Well drained; medium to high runoff; moderately slow permeability.
USE AND VEGETATION: Halfcircle soils are used for rangeland and woodland. The potential natural vegetation is Douglas-Fir, with an understory of Mountain snowberry and Pine reedgrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho. This series is not extensive. MLRA 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Bear Lake County, Idaho 2008. The name is taken from a local ranch where the series is mapped.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the mineral soil surface to 16 inches (A1, A2, and Btk horizons)
Argillic horizon - the zone from 7 to 16 inches (Btk horizon)
Calcic horizon - the zone from 16 to 22 inches (Bk horizon)
Particle-size control section - the zone from 7 and 16 inches (Btk horizon)
Paralithic contact - calcareous siltstone at 42 inches (Cr horizon)
Note: Series classification updated from the 8th to the 10th edition. The classification changed from Loamy-skeletal, mixed, superactive Pachic Argicryolls to Loamy-skeletal, mixed, superactive Calcic Pachic Argicryolls.