LOCATION IBEX MTEstablished Series
TAXONOMIC CLASS: Coarse-loamy over sandy or sandy-skeletal, mixed, superactive, acid, frigid Typic Endoaquepts
TYPICAL PEDON: Ibex silt loam, forested (colors are for moist soil unless otherwise noted).
A--0 to 1 inches; very dark grayish brown (10YR 3/2) silt loam, light brownish gray (10YR 6/2) dry; weak fine and medium granular structure; hard, very friable, nonsticky and nonplastic; many very fine and fine roots; strongly acid (pH 5.2); abrupt smooth boundary. (1 to 2 inches thick)
E--1 to 4 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; weak fine and medium granular structure; hard, very friable, nonsticky and nonplastic; many very fine and common fine roots; strongly acid (pH 5.2); abrupt wavy boundary. (1 to 3 inches thick)
Bw1--4 to 9 inches; brown (10YR 5/3) silt loam, very pale brown (10YR 7/3) dry; weak very coarse prismatic structure parting to weak medium subangular blocky; slightly hard, very friable, nonsticky and nonplastic; common very fine and fine roots; few distinct strong brown (7.5YR 5/6) redox concentrations; strongly acid (pH 5.2); clear wavy boundary.
Bw2--9 to 25 inches; grayish brown (10YR 5/2) silt loam, light gray (10YR 7/2) dry; weak very coarse prismatic structure parting to weak medium subangular blocky; slightly hard, very friable, nonsticky and nonplastic; common very fine and fine roots; few distinct strong brown (7.5YR 5/6) redox concentrations; strongly acid (pH 5.4); gradual wavy boundary. (Combined thickness of Bw horizons is 11 to 25 inches)
C1--25 to 29 inches; variegated colors consisting of about 80 percent grayish brown (10YR 5/2) and 20 percent gray (10YR 5/1) fine sandy loam, light gray (10YR 7/2 and 10YR 7/1) dry; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine roots; common distinct strong brown (7.5YR 4/6) redox concentrations; strongly acid (pH 5.4); clear wavy boundary. (2 to 4 inches thick)
2C2--29 to 52 inches; gray (10YR 5/1) extremely gravelly coarse sand, light gray (10YR 7/1) dry; single grain; loose, nonsticky and nonplastic; few very fine roots; 10 percent cobbles, 55 percent pebbles; strongly acid (pH 5.4); clear wavy boundary. (16 to 28 inches thick)
2C3--52 to 60 inches; dark brown (7.5YR 4/4) extremely gravelly coarse sand, brown (7.5YR 5/4) dry; single grain; loose, nonsticky and nonplastic; few very fine roots; 10 percent cobbles, 55 percent pebbles; strongly acid (pH 5.4).
TYPE LOCATION: Sanders County, Montana; 600 feet west and 200 feet south of the northeast corner of section 16, T. 28 N., R. 33 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 45 degrees F.
Depth to 2C horizon - 25 to 35 inches.
Depth to seasonal high water table - 12 to 24 inches (April to June).
A horizon - Value: 4, 5 or 6 dry, 2 or 3 moist
Chroma: 2 or 3
Clay content: 4 to 12 percent; less than 15 percent fine sand or coarser
Reaction: pH 4.5 to 5.5
E horizon - Clay content: 4 to 12 percent; less than 15 percent fine sand or coarser
Reaction: 4.5 to 5.5
Bw1 horizon - Clay content: 4 to 12 percent; less than 15 percent fine sand or coarser
Reaction: pH 4.5 to 5.5
Bw2 horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4 or 5 moist
Texture: silt loam or very fine sandy loam
Clay content: 4 to 12 percent; less than 15 percent fine sand or coarser
Reaction: pH 4.5 to 5.5
C1 horizon - Hue: 10YR, 2.5Y or 5Y
Value: 5, 6 or 7 dry; 3, 4 or 5 moist
Chroma: 0, 1 or 2
Texture: fine sandy loam or sandy loam
Clay content: 0 to 5 percent
Reaction: pH 4.5 to 5.5
2C2 horizon - Value: 6 or 7 dry; 4 or 5 moist
Texture: coarse sand, sand, loamy coarse sand, or loamy sand
Clay content - 0 to 5 percent
Coarse fragments: 60 to 80 percent--10 to 20 percent cobbles, 50 to 60 percent pebbles
Reaction: pH 4.5 to 5.5
2C3 horizon - Value: 5 or 6 dry; 4 or 5 moist
Chroma: 4 or 6
Texture: coarse sand, sand, loamy coarse sand, or loamy sand
Clay content - 0 to 5 percent
Coarse fragments: 60 to 80 percent--10 to 20 percent cobbles, 50 to 60 percent pebbles
Reaction: pH 4.5 to 5.5
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - low stream terraces and flood plains.
Elevation - 2,200 to 2,800 feet.
Slope- 0 to 2 percent.
Parent material - alluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 28 to 34 inches.
Mean annual temperature - 42 to 45 degrees F.
Frost-free period - 70 to 90 days.
DRAINAGE AND PERMEABILITY: Poorly drained, moderate over rapid permeability.
USE AND VEGETATION: Ibex soils are used for timber production and wildlife habitat. Potential native vegetation is mainly western hemlock, western redcedar, grand fir, and Engelmann spruce, with an understory of queencup beadlily, wild sarsparilla, horsetail, lady-fern, violet, and twisted stalk.
DISTRIBUTION AND EXTENT: Ibex soils are of small extent in the valleys of northwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sanders County, Montana 1997.
REMARKS: Soils Interpretation Record: MT1513. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (A, E, and Bw1 horizons); a cambic horizon from 4 to 25 inches (Bw1 and Bw2 horizons); a particle-size control section from 10 to 40 inches (Bw2, C1, 2C2 horizons). Ibex soils have an aquic moisture regime and a frigid temperature regime.
ADDITIONAL DATA: Lab data S93MT-089-005.