LOCATION ILLIANO MTEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy Lithic Haplocryepts
TYPICAL PEDON: Illiano very flaggy ashy sandy loam, in non-stocked forest (colors are for dry soil unless otherwise noted).
A--0 to 4 inches; grayish brown (10YR 5/2) very flaggy ashy sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, very friable, nonsticky and nonplastic; many very fine and fine roots; 25 percent flagstones, 30 percent gravel; slightly acid (pH 6.4); clear wavy boundary. (1 to 6 inches thick)
Bw--4 to 11 inches; light brownish gray (10YR 6/2) very flaggy ashy sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots; 25 percent flagstones, 30 percent gravel; neutral (pH 6.8); abrupt smooth boundary. (5 to 14 inches thick)
R--11 inches; light gray (5Y 7/1) fractured hard welded tuff bedrock.
TYPE LOCATION: Deer Lodge County, Montana; 100 feet east and 2350 feet north of the SW corner of sec. 14, T. 3 N., R. 11 W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 32 to 40 degrees F.
Mean summer soil temperature - 40 to 46 degrees F.
Moisture control section - between 8 inches and the lithic contact.
Volcanic glass - 30 to 50 percent in the coarse silt and sand fraction.
Acid oxalate Al + 1/2 Fe - .12 to .20 percent.
Depth to R horizon - 10 to 20 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 1 or 2
Clay content: 10 to 20 percent
Rock fragments: 35 to 60 percent--15 to 25 percent flagstones, 20 to 35 percent gravel
Reaction: pH 5.6 to 6.5
Bw horizon - Hue: 10YR, 2.5Y or 5Y
Value: 5, 6 or 7 dry, 4, 5 or 6 moist
Chroma: 1, 2 or 3
Texture: ashy loam, ashy sandy loam, or ashy coarse sandy loam
Clay content: 5 to 18 percent
Rock fragments: 35 to 60 percent--15 to 25 percent flagstones, 20 to 35 percent gravel
Reaction: pH 5.6 to 7.3
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform- hills; mountains.
Elevation - 5,000 to 8,000 feet.
Slope - 8 to 70 percent.
Parent material - residuum from welded tuff or rhyolite bedrock.
Climate - long, cold winters; cool, moist springs; cool, hort summers.
Mean annual precipitation - 18 to 30 inches.
Mean annual air temperature - 30 to 38 degrees F.
Frost-free period - 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bendoh, Coslaw, Karloff, and Pax soils. Bendoh soils are deep to a lithic contact. Coslaw and Karloff soils are moderately deep to a lithic contact. Pax soils are moderately deep to a paralithic contact. These soils are on similar landform positions.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Illiano soils are mainly used for woodland, watershed, and as wildlife habitat. The potential overstory vegetation is mainly subalpine fir, lodgepole pine, and Douglas-fir (at lower elevations). Englemann spruce and whitebark pine are at higher elevations. Understory vegetation is mainly elk sedge, pinegrass, lupine, Oregongrape and common juniper.
DISTRIBUTION AND EXTENT: Illiano soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Deer Lodge County, Montana, 1999.
REMARKS: Soil interpretive record: MT1742. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the surface to 7 inches mxied (A and part of the Bw horizon); a cambic horizon from 4 to 11 inches (Bw horizon); welded tuff bedrock at 11 inches (R horizon). Illiano soils have a cryic temperature regime and an ustic moisture regime bordering on udic.
The 3/2008 description reflects a change in classification from Ashy-skeletal, glassy Lithic Eutrocryepts to Ashy-skeletal, glassy Lithic 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.