LOCATION LACREEK WY
Tentative Series
Rev. DMM-RJS
05/2011
LACREEK SERIES
The Lacreek series consists of very deep, well drained soils that formed in slope alluvium or colluvium derived siltstone. These soils are on mountain slopes and scarp slopes. Slopes are 20 to 75 percent. Mean annual precipitation is about 430 mm, and mean annual air temperature is about 1 degree C.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Pachic Calcicryolls
TYPICAL PEDON: Lacreek channery silt loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 10 cm; dark gray (10YR 4/1) channery silt loam, very dark gray (10YR 3/1) moist; moderate very fine granular structure; soft, very friable, nonsticky and nonplastic; many fine roots; many fine interstitial pores; 15 percent channers; finely disseminated calcium carbonate; strongly effervescent; moderately alkaline (pH 8.1); clear smooth boundary. (10 to 25 cm thick)
ABk--10 to 33 cm; dark grayish brown (10YR 4/2) channery silt loam, very dark grayish brown (10YR 3/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many fine roots; many fine interstitial pores; 15 percent channers; 20 percent prominent calcium carbonate coats on bottom surfaces of rock fragments and finely disseminated calcium carbonate; violently effervescent; slightly alkaline (pH 7.8); clear smooth boundary. (0 to 25 cm thick)
Bk1--33 to 66 cm; brown (10YR 4/3) channery silt loam, dark brown (10YR 3/3) moist; moderate very fine granular structure; soft, very friable, slightly sticky, slightly plastic; many fine roots; many fine interstitial pores; 15 percent channers; 20 percent prominent calcium carbonate coats on bottom surfaces of rock fragments, 10 percent calcium carbonate masses in matrix, and finely disseminated calcium carbonate; violently effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (15 to 40 cm thick)
Bk2--66 to 130 cm; grayish brown (10YR 5/2) channery silt loam, dark grayish brown (10YR 4/2) moist; moderate very fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many fine roots; many fine interstitial pores; 15 percent channers; 20 percent prominent calcium carbonate coats on bottom surfaces of rock fragments, 15 percent calcium carbonate masses in matrix, and finely disseminated calcium carbonate; violently effervescent; moderately alkaline (pH 8.1); clear smooth boundary. (50 to 70 cm thick)
BCk--130 to 200 cm; light brownish gray (10YR 6/2) very channery clay loam, grayish brown (10YR 5/2) moist; weak very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine interstitial pores; 40 percent channers; 40 percent prominent calcium carbonate coats on bottom surfaces of rock fragments and finely disseminated calcium carbonate; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Sublette County, Wyoming: Located approximately 17 miles NW of LaBarge, WY.; Located approximately 1,790 feet south and 930 feet east of the northwest corner of section 4, T. 27N, R. 115W; USGS Coal Creek, Wyoming topographic quadrangle; 42 degrees 21 minutes 35.00 seconds north latitude and 110 degrees 30 minutes 0.00 seconds west longitude
RANGE IN CHARACTERISTICS:
Soil temperature - 1.5 to 3.5 degrees C.
Mollic epipedon - greater than or equal to 50 cm
Depth to calcic horizon - 50 to 70 cm
A horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2; dry or moist
Clay content: 18 to 24 percent
Rock fragments: 15 to 30 percent--10 to 30 percent channers, 0 to 10 percent flagstones
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.8 to 8.4
ABk horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: loam, silt loam
Clay content: 20 to 27 percent
Rock fragments: 15 to 30 percent--10 to 30 percent channers, 0 to 10 percent flagstones
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.8 to 8.4
Bk1 horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: loam, silt loam
Clay content: 20 to 27 percent
Rock fragments: 15 to 30 percent--10 to 30 percent channers, 0 to 10 percent flagstones
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.4
Bk2 horizon
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3; dry or moist
Texture: loam, silt loam
Clay content: 20 to 27 percent
Rock fragments: 15 to 30 percent--10 to 30 percent channers, 0 to 10 percent flagstones
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.9 to 8.4
BCk horizon
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3; dry or moist
Texture: clay loam, loam, silt loam
Clay content: 20 to 35 percent
Rock fragments: 35 to 50 percent--30 to 50 percent channers, 0 to 10 percent flagstones
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - mountain slopes, scarp slopes
Elevation - 2,320 to 2,740 meters
Slope - 20 to 75 percent
Parent Material - slope alluvium or colluvium derived from siltstone
Climate - long, cold winters; cool, moist springs; short, cool summers
Mean annual precipitation - 380 to 485 mm with peak periods of precipitation occurring during the spring
Mean annual air temperature - 0.5 to 2.0 degrees C.
Frost-free period - 25 to 45 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Lacreek soils are primarily used for rangeland. The potential native vegetation is mainly mountain big sagebrush, Letterman's needlegrass, Columbia needlegrass, snowberry and Idaho fescue.
DISTRIBUTION AND EXTENT: Lacreek soils are of minor extent in southwestern Wyoming. MLRA - 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES PROPOSED: Sublette County, Wyoming, 2011. The series is derived from a local landmark.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 66 cm (A, ABk, Bk1 horizons)
Calcic horizon - from 66 to 200 cm (Bk2, BCk horizons)
Particle-size control section - from 25 to 100 cm (part of ABk, Bk1, part of Bk2 horizons)
Lacreek soils have a cryic temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.