LOCATION EVARO MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Lamellic Haplocryepts
TYPICAL PEDON: Evaro gravelly loam, forested (colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches; slightly decomposed forest litter.
A--2 to 8 inches; light yellowish brown (10YR 6/4) gravelly ashy loam, dark yellowish brown (10YR 4/4) moist; weak medium granular structure; soft, very friable, nonsticky and slightly plastic; many fine and medium roots; many fine pores; 25 percent gravel; ash influenced with about 50 percent glass and a bulk density of less than .95 g/cc; slightly acid (pH 6.4); clear smooth boundary. (3 to 6 inches thick)
2E1--8 to 17 inches; light brownish gray (10YR 6/2) very gravelly loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many fine and medium roots; common fine pores; 40 percent gravel, 10 percent cobbles; slightly acid (pH 6.2); clear wavy boundary.
2E2--17 to 25 inches; light gray (10YR 7/2) very gravelly sandy loam, grayish brown (10YR 5/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots; common fine pores; 45 percent gravel, 10 percent cobbles; slightly acid (pH 6.4); gradual wavy boundary. (The combined thickness of the E horizons is 12 to 24 inches.)
2E and Bt--25 to 60 inches; E part (75 percent) is very pale brown (10YR 7/3) extremely gravelly sandy loam, brown (10YR 5/3) moist; B part (25 percent) is few discontinuous pale brown (10YR 6/3) extremely gravelly fine sandy loam lamellae 1/16- to 1/4-inch thick, brown (10YR 5/3) moist; texture mixed is extremely gravelly sandy loam; massive; slightly hard, very friable, nonsticky and nonplastic; few fine roots; common fine pores; 60 percent gravel, 15 percent cobbles; neutral (pH 6.6).
TYPE LOCATION: Granite County, Montana; 900 feet east and 400 feet north of the S 1/4 corner of sec. 2, T. 12 N., R. 14 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 39 to 45 degrees F.
Moisture control section - between 8 and 24 inches.
Moist bulk density is less than 0.95 g/cc to a depth of 6 inches or less and does not meet the thickness requirement for the vitrandic or andic intergrade.
A C horizon is allowed.
A horizon - Hue: 10YR or 7.5YR
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3, 4, or 5
Texture: ashy loam or ashy silt loam
Glass: 35 to 60 percent
Clay content: 5 to 15 percent
Rock fragments: 15 to 70 percent--0 to 20 percent stones, 0 to 25 percent cobbles, 15 to 25 percent gravel
Reaction: pH 5.6 to 6.5
2E horizons - Hue: 10YR or 7.5YR
Value: 6, 7, or 8 dry; 5, 6, or 7 moist
Chroma: 2 or 3
Texture: loam or sandy loam
Clay content: 5 to 15 percent
Rock fragments: 40 to 80 percent--5 to 30 percent cobbles; 35 to 50 percent gravel
Reaction: pH 5.6 to 7.3
2E and Bt horizon - Hue: 10YR or 7.5YR
Value: E part 6 or 7 dry, 4, 5 or 6 moist; B part 5 or 6 dry, 4 or 5 moist
Chroma: E part 2 or 3; B part 3 or 4
Texture: loam or sandy loam
Clay content: 5 to 18 percent--lamellae has less than 3 percent clay increase
Rock fragments: 60 to 80 percent--5 to 15 percent cobbles; 55 to 65 percent gravel
Reaction: pH 5.6 to 7.3
COMPETING SERIES:
Blackleed (MT) - does not have a albic horizon; has lamellae with an increase of 3 percent or more clay; has a lithic contact at depths of 40 to 60 inches.
GEOGRAPHIC SETTING:
Landform- mountains; hills.
Elevation - 4,500 to 9,100 feet.
Slope - 4 to 65 percent.
Parent material - colluvium derived from argillite and quartzite bedrock.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 20 to 40 inches, much of which falls as snow and as spring rain.
Mean annual air temperature - 36 to 43 degrees F.
Frost-free period - 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Garlet, Whitore, Winkler, and Worock soils. These soils lack the thin layer of volcanic ash influence.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; moderately rapid permeability.
USE AND VEGETATION: Evaro soils are used for timber production, watershed, wildlife habitat, and recreation. The native vegetation is Douglas fir, lodgepole pine, subalpine fir, and western larch with an understory of grouse whortleberry, blue huckleberry, pinegrass, rusty menziesia, twinflower, and common beargrass.
DISTRIBUTION AND EXTENT: Evaro soils are of moderate extent in western Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Granite County (Philipsburg-Drummond area), Montana, 1972.
REMARKS: Soil interpretation record: MT0572. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (Oi, A horizons); an albic horizon from 8 to 25 inches; a cambic horizon from 25 to 60 inches (2E/Bw horizon); a particle-size control section from 12 to 42 inches (2E1, 2E2, 2E/Bw horizons). Evaro soils have a cryic temperature regime and a udic moisture regime.
The 3/2008 description reflects a change in classification from Loamy-skeletal, mixed, superactive Lamellic Eutrocryepts to Loamy-skeletal, mixed, superactive Lamellic Haplocryepts due to revision of the cryepts great groups and subgroups. The competing series section was not updated and should be reviewed after all the cryepts have been re-classified.