LOCATION GRADE WY
Tentative Series
IRD DJP/CBR
03/2018
GRADE SERIES
The Grade series consists of very deep, well drained soils that formed in colluvium derived from sandstone and quartzite. These soils are on hillslopes and mountain slopes. Slopes are 8 to 65 percent. Mean annual precipitation is about 550 mm, and mean annual air temperature is about 0.8 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Typic Argicryolls
TYPICAL PEDON: Grade gravelly silt loam, in forestland (colors are for dry soil unless otherwise noted).
A--0 to 13 cm; dark grayish brown (10YR 4/2) gravelly silt loam, black (10YR 2/1) moist; strong coarse granular structure; moderately hard, firm, moderately sticky, moderately plastic; many fine, very fine and common coarse and very coarse roots throughout; many fine and very fine irregular pores; 20 percent gravels; neutral (pH 6.6); clear wavy boundary. (6 to 15 cm thick)
Bt1--13 to 36 cm; grayish brown (10YR 5/2) very gravelly silt loam, very dark grayish brown (10YR 3/2) moist; strong fine subangular blocky structure; moderately hard, firm, moderately sticky, moderately plastic; many fine, very fine and common coarse roots throughout; many fine and very fine dendritic tubular pores; 35 percent gravel and 5 percent cobbles; 15 percent distinct clay films on all faces of peds; neutral (pH 6.6); abrupt wavy boundary. (19 to 25 cm thick)
Bt2--36 to 52 cm; pale brown (10YR 6/3) very gravelly clay loam, brown (10YR 4/3) moist; strong fine subangular blocky structure; moderately hard, firm, very sticky, very plastic; many fine, very fine and common coarse roots throughout; many fine and very fine dendritic tubular pores; 35 percent gravel and 20 cobbles; 20 percent distinct clay films on all faces of peds; slightly acid (pH 6.4); abrupt wavy boundary.
Bt3-- 52 to 114 cm; pale brown (10YR 6/3) very gravelly clay, brown (10YR 4/3) moist; strong medium angular blocky structure; moderately hard, firm, very sticky, very plastic; many very fine and common fine roots throughout; many fine and very fine dendritic tubular pores; 40 percent gravel and 5 percent cobbles; 30 percent distinct clay films on all faces of peds; neutral (pH 7.2); abrupt wavy boundary. (combined thickness of Bt2 and Bt3 is 74 to 80 cm)
C-- 114 to 150 cm; pale brown (10YR 6/3) very gravelly clay, brown (10YR 4/3) moist; massive; moderately hard, firm, very sticky, very plastic; many fine dendritic tubular pores; 40 percent gravel and 5 percent cobbles; neutral (pH 7.2).
TYPE LOCATION: Lincoln County, Wyoming; USGS South Fork Mountain, Wyoming, topographic quadrangle; 42 degrees 3 minutes 0.25 seconds north latitude and 110 degrees 32 minutes 47.20 seconds west longitude, datum WGS84.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature -- 1.0 to 3.1 degrees C.
Mollic epipedon thickness -- 26 to 38 cm
Particle-size control section (weighted averages)
Clay content -- 26 to 34 percent
Total rock fragments -- 35 to 50 percent
A horizon
Hue: 7.5YR or 10YR, dry or moist
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1 or 2, dry or moist
Texture (less than 2 mm fraction): loam, silt loam
Clay content: 16 to 25 percent
Rock fragments: 2 to 25 percent gravel
Reaction: pH 6.4 to 7.0
Bt1 horizon
Hue: 5YR to 10YR, dry or moist
Value: 4 or 5 dry; 2.5 or 3 moist
Chroma: 2 or 3, dry or moist
Texture (less than 2 mm fraction): loam, silt loam, clay loam
Clay content: 24 to 34 percent
Rock fragments: 35 to 45 percent gravel and 5 to 10 percent cobbles
Reaction: pH 6.1 to 7.0
Bt2 and Bt3 horizons
Hue: 5YR to 10YR, dry or moist
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture (less than 2 mm fraction): clay loam, clay
Clay content: 30 to 47 percent
Rock fragments: 25 to 45 percent gravel and 0 to 25 percent cobbles
Reaction: pH 6.6 to 7.3
C horizon
Hue: 5YR to 10YR, dry or moist
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture (less than 2 mm fraction): clay loam, clay
Clay content: 38 to 48 percent
Rock fragments: 35 to 45 percent gravel and 0 to 10 percent cobbles
Reaction: pH 6.6 to 7.3
COMPETING SERIES:
Elkpeak (MT) -- soils have less than 30 percent clay in the lower part of the subsoil
Elwood (UT) -- soils are moderately deep to lithic contact
Ezbin (ID) -- soils have less than 30 percent clay in the lower part of the subsoil
Lakemountain (WY) -- soils have secondary carbonates
Pohlod (MT) -- soils are moderately deep to lithic contact
Quazar (CO) -- soils have a lithologic discontinuity
Tahquats (ID) -- soils have pH values of less than 6.1 in the Bt horizons
Wander (CO) -- soils receive most of its precipitation in July and August
GEOGRAPHIC SETTING:
Landform -- hillslopes and mountain slopes
Elevation -- 2,220 to 2,700 meters
Slope -- 8 to 65 percent
Parent material -- colluvium derived from sandstone and quartzite
Climate -- long, cold winters; cool, moist springs; short, cool summers
Relative effective annual precipitation -- 610 to 890 mm with peak periods of precipitation occurring during the spring
Mean annual air temperature -- 0.0 to 2.1 degrees C.
Frost-free period -- 10 to 40 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained, 0.5 to 15.0 um/sec
USE AND VEGETATION: Grade soils are primarily used for forestland. The potential native vegetation is subalpine fir, aspen, pinegrass, snowberry and mountain big sagebrush.
DISTRIBUTION AND EXTENT: Grade soils are of small extent in southwestern Wyoming. MLRA 43B and 46.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Lincoln County, Wyoming, 2018. The name is derived from a local landmark.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon -- 0 to 36 cm (A and Bt1 horizons)
Argillic horizon -- 13 to 114 cm (Bt1, Bt2 and Bt3 horizons)
Particle-size control section -- 13 to 63 cm (Bt1, Bt2 and part of the Bt3 horizons)
Grade soils have a cryic temperature regime and an udic moisture regime.
Taxonomic version: Twelfth edition, 2014
National Cooperative Soil Survey
U.S.A.