LOCATION SWAN FLAT IDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Xeric Calcicryolls
TYPICAL PEDON: Swan Flat silt loam--rangeland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 5 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; soft, very friable, non-sticky and non-plastic; many very fine and fine roots; many fine irregular pores; slightly effervescent; 5 percent channers; slightly alkaline (pH 7.4); gradual wavy boundary. (5 to 10 inches thick)
A2--5 to 9 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, fine and few medium roots; many fine irregular pores; slightly effervescent; 5 percent channers; slightly alkaline (pH 7.6); clear wavy boundary. (0 to 5 inches thick)
Bk1--9 to 15 inches; brown (10YR 5/3) channery silt loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; soft, very friable, non-sticky and non-plastic; many very fine, fine and few medium roots; many fine tubular pores; few fine carbonate nodules in the matrix; strongly effervescent; 25 percent channers; slightly alkaline (pH 7.8); gradual wavy boundary. (5 to 15 inches thick)
Bk2--15 to 30 inches; pale brown (10YR 6/3) very channery silt loam, dark grayish brown (10YR 4/2) moist; moderate fine subangular blocky structure; soft, very friable, non-sticky and non-plastic; common very fine and few fine roots; common fine tubular pores; few fine carbonate nodules in the matrix; strongly effervescent; 30 percent channers and 5 percent flagstones; slightly alkaline (pH 7.8); gradual wavy boundary. (10 to 20 inches thick)
Bk3--30 to 56 inches; pale brown (10YR 6/3) very channery silt loam, brown (10YR 5/3) moist; weak fine subangular blocky structure; soft, very friable, non-sticky and non-plastic; common very fine and few fine roots; few fine tubular pores; common fine carbonate nodules in the matrix; violently effervescent; 45 percent channers and 5 percent flagstones; moderately alkaline (pH 8.2); gradual wavy boundary. (10 to 30 inches thick)
Bk4--56 to 60 inches; very pale brown (10YR 8/3) very channery silt loam, pale brown (10YR 6/3) moist; weak coarse prismatic structure; soft, very friable, non-sticky and non-plastic; few very fine roots; few fine irregular pores; few fine carbonate masses in the matrix; violently effervescent; 30 percent channers and 15 percent flagstones; moderately alkaline (pH 8.2); gradual wavy boundary.
TYPE LOCATION: Bear Lake County, Idaho; approximately 1 miles west of Paris; about 2,400 feet north and 100 feet east of the southwest corner of section 10, T. 14 S., R. 43 E.; USGS Paris 7.5 minute topographic quadrangle; 42 degrees 13 minutes 10 seconds north latitude and 111 degrees 25 minutes 27 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.
Thickness of mollic epipedon - 7 to 15 inches (may extend into the Bk horizon)
Depth to calcic horizon - 5 to 15 inches (calcareous to the surface when mixed to 7 inches)
Mean annual soil temperature - 39 to 42 degrees F.
Mean summer soil temperature - less then 59 degrees F. Cryic soil temperature regime.
Particle-size control section
Clay content - 10 to 17 percent
Rock fragments - 35 to 55 percent (30 to 45 percent gravel or channers, 5 to 10 percent cobbles or flagstones)
A horizons
Hue - 7.5YR or 10YR
Value - 3 to 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture - silt loam
Clay content - 18 to 24 percent
Rock fragments - 5 to 15 percent (5 to 10 percent gravel or channers, 0 to 5 percent cobbles or flagstones)
Calcium carbonate equivalent - 2 to 10 percent
Reaction - slightly alkaline or moderately alkaline (pH 7.4 to 8.2)
Bk horizons
Hue - 7.5YR, 10YR, 2.5Y
Value - 5 to 8 dry, 3 to 6 moist
Chroma - 2 or 3 dry or moist
Textures - gravelly sandy loam, gravelly loam, gravelly silt loam, or their very gravelly, channery, very channery, very cobbly or very flaggy analogues
Clay content - 10 to 17 percent
Rock fragments - 20 to 55 percent (25 to 45 percent gravel or channers, 0 to 20 percent cobbles or flagstones)
Calcium carbonate equivalent - 15 to 35 percent
Reaction - slightly or moderately alkaline (pH 7.8 to 8.4)
COMPETING SERIES: This is the Vo (T) series. Vo soils have horizons with accumulations of secondary silica and occur in areas that average 11 to 14 inches of annual precipitation.
GEOGRAPHIC SETTING:
Landform: hillslopes, mountain slopes, and summits (dominantly north and east aspects)
Elevation: 5,900 to 7,500 feet
Slope: 10 to 50 percent
Parent material: mixed alluvium and/or slope alluvium derived from limestone or calcareous siltstone
Climate: long, cold winters; moist springs; warm, dry, summers.
Mean annual precipitation: 16 to 24 inches
Mean annual air temperature: 36 to 40 degrees F.
Frost-free season: 50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Danburn, Grunder (T), and Richollow (T) series. Danburn and Grunder soils are fine-loamy, have argillic horizons and have forest overstory of Douglas fir and aspen. Richollow soils are shallow over limestone bedrock and are on ridges and summits near areas of rock outcrop.
DRAINAGE AND PERMEABILITY: Well drained; low to medium surface runoff; moderately rapid permeability.
USE AND VEGETATION: Swan Flat soils are used for rangeland and wildlife habitat. The present vegetation is mainly mountain big sagebrush, bluebunch wheatgrass, Idaho fescue, snowberry, serviceberry, arrowleaf balsamroot and twisted leaf.
DISTRIBUTION AND EXTENT: Southeastern Idaho. These soils are of small extent. MLRA 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Bear Lake County, Idaho, 2008. The name comes from nearby Swan Flat.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 15 inches (A1, A2 and Bk1 horizons).
Calcic horizon - The zone from 9 to 60 inches (Bk1, Bk2, Bk3 and Bk4 horizons).