LOCATION SWIFTCREEK WY
Tentative Series
Rev. JGM-RJS
10/2013
SWIFTCREEK SERIES
The Swiftcreek series consists of very deep, well drained soils that formed in colluvium, slope alluvium or slide deposits derived from limestone. These soils occur on hills and rotational slides. Slopes are 10 to 50 percent. Mean annual precipitation is about 530 mm and mean annual air temperature is about 5.6 degrees C.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Haplustepts
TYPICAL PEDON: Swiftcreek gravelly loam, in rangeland (colors are for dry soil unless otherwise stated).
A--0 to 9 cm; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine, and few medium roots; few fine and common very fine pores; 15 percent subangular limestone gravel; finely disseminated calcium carbonate; strongly effervescent; moderately alkaline (pH 8.0); gradual smooth boundary. (5 to 15 cm thick)
Bw1--9 to 30 cm; brown (10YR 5/3) gravelly loam, dark yellowish brown (10YR 3/4) moist; moderate medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine and few fine roots; few fine and common very fine dendritic tubular pores; 15 percent subangular limestone gravel; finely disseminated calcium carbonate; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary.
Bw2--30 to 68 cm; pale brown (10YR 6/3) gravelly sandy clay loam, brown (10YR 4/3) moist; moderate coarse subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine and few fine roots; few fine and very fine dendritic tubular pores; 20 percent subangular limestone gravel, 5 percent limestone flagstones; finely disseminated calcium carbonate; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (combined thickness of Bw1 and Bw2 horizons - 40 to 70 cm)
C--68 to 200 cm; very pale brown (10YR 7/3) very gravelly sandy clay loam, brown (10YR 5/3) moist; massive; soft, friable, moderately sticky and slightly plastic; few very fine roots; few very fine dendritic tubular pores; 25 percent subangular limestone gravel, 15 percent subangular limestone flagstones; finely disseminated calcium carbonate; violently effervescent; strongly alkaline (pH 8.6).
TYPE LOCATION: Lincoln County, Wyoming; 41 degrees 52 minutes 24.80 seconds north latitude and 110 degrees 46 minutes 45.50 seconds west longitude; NAD83; UTM 518314 meters E, 4635757 meters N, zone 12.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5.6 to 7.8 degrees C.
Depth to top of cambic horizon - 5 to 15 cm
Thickness of cambic horizon - 40 to 70 cm
Note: This soil does not have secondary calcium carbonate accumulations.
A horizon
Hue: 7.5YR or 10YR; dry or moist
Value: 4 or 5 dry; 3 or 4
Chroma: 2 or 3; dry or moist
Clay content: 20 to 25 percent
Rock fragments: 15 to 25 percent limestone gravel
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.9 to 8.5
Bw1, Bw2 horizons
Hue: 7.5YR or 10YR; dry or moist
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 3 or 4; dry or moist
Texture: loam, sandy clay loam
Clay content: 20 to 27 percent
Rock fragments: 15 to 30 percent--15 to 30 percent limestone gravel, 0 to 10 percent limestone flagstones
Calcium carbonate equivalent: 25 to 35 percent
Sodium adsorption ration: 3 to 8 percent
Reaction: pH 8.2 to 8.8
C horizon
Hue: 7.5YR or 10YR; dry or moist
Value: 5 to 7 dry; 4 to 6 moist
Chroma: 2 or 3; dry or moist
Texture: loam, sandy clay loam
Clay content: 20 to 27 percent
Rock fragments: 35 to 50 percent--20 to 35 percent limestone gravel, 10 to 25 percent limestone flagstones
Calcium carbonate equivalent: 35 to 45 percent
Sodium adsorption ration: 3 to 8 percent
Reaction: pH 8.2 to 8.8
COMPETING SERIES:
Arikara (ND) - is noncalcareous at the surface
Broadus (MT) - is noncalcareous at the surface
Doney (MT) - is moderately deep to a paralithic contact
Helper (MT) - is moderately deep to a paralithic contact
Macar (MT) - has a calcium carbonate equivalent of less than 15 percent throughout
Mara (NM) - has a calcium carbonate equivalent of less than 15 percent throughout
Slategoat (MT) - has a calcium carbonate equivalent of less than 15 percent throughout
GEOGRAPHIC SETTING:
Landform - hills and rotational slides
Elevation - 2,070 to 2,380 meters
Slope - 10 to 50 percent
Parent material - colluvium, slope alluvium or slide deposits derived from limestone
Climate - long, cold winters; short, cool summers; peak precipitation occurs from March to June
Mean annual precipitation - 450 to 610 mm
Mean annual air temperature - 4.4 to 6.7 degrees C
Frost-free period - 60 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Swiftcreek soils are primarily used as rangeland and wildlife habitat. The potential native vegetation may include mountain big sagebrush, snowberry, antelope bitterbrush, and thickspike wheatgrass.
DISTRIBUTION AND EXTENT: Swiftcreek soils are of small extent in southwestern Wyoming. MLRA - 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Lincoln County Area, Wyoming, Southern Part in 2013.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 9 cm (A horizon)
Cambic horizon - 9 to 68 cm (Bw1, Bw2 horizons)
Particle size control section - 25 to 100 cm (part of Bw1, Bw2, part of C horizons)
Swiftcreek soils have a frigid temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.