LOCATION CHALLIS IDEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Calcic Argixerolls
TYPICAL PEDON: Challis gravelly clay loam, on a 38 percent northeast-facing slope at 6,350 feet elevation in rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; brown (10YR4/3) gravelly clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine, common fine and few medium roots; many very fine irregular and few very fine tubular pores; 25 percent gravel and 5 percent cobbles; neutral (pH 7.0); clear wavy boundary. ( 3 to 4 inches thick)
Bt1--4 to 12 inches; brown (10YR 5/3) very gravelly clay, dark brown (10YR 3/3) moist; strong very fine and fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many very fine and few fine and medium roots; common very fine and fine tubular and few very fine irregular pores; many distinct clay films on faces of peds and in pores; 40 percent gravel; neutral (pH 7.2); clear wavy boundary. (7 to 11 inches thick)
Bt2--12 to 23 inches; brown (10YR 5/3) very gravelly clay, dark grayish brown (10YR 4/2) moist; strong very fine and fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; common very fine and fine tubular and few very fine irregular pores; many distinct clay films on faces of peds and in pores; 40 percent gravel and 5 percent cobbles; neutral (pH 7.2); gradual wavy boundary. (5 to 21 inches thick)
Bkq1--23 to 38 inches; light brownish gray (10YR 6/2) very gravelly loam, grayish brown (10YR 5/2) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; common very fine and fine tubular and few very fine irregular pores; 45 percent gravel and 5 percent cobbles; lime and silica layers 1 to 2mm in thickness on undersides of rock fragments; 15 percent soft secondary lime in veins along root channels; strongly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (10 to 15 inches thick)
Bkq2--38 to 60 inches; light brownish gray (10YR 6/2) extremely gravelly loam, grayish brown (10YR 5/2) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; common very fine irregular pores; 50 percent gravel and 10 percent cobbles; lime and silica layers 1 to 2mm in thickness on undersides of rock fragments; 10 percent soft secondary lime in veins along root channels; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Custer County, Idaho; about 8 miles northwest of Challis, Idaho; about 1,280 feet west and 2,500 feet south from the northeast corner of section 24, T. 15 N., R. 18 E. (Latitude 44 degrees, 36 minutes, 56 seconds North, Longitude 114 degrees, 16 minutes, 41 seconds West)
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 39 to 44 degrees F.
Average summer soil temperature - 59 to 67 degrees F.
Particle-size control section (Bt horizon):
Percent clay - 40 to 50 percent
Rock fragments - 35 to 60 percent
Mollic epipedon thickness - 10 to 15 inches
Depth to secondary carbonates - 15 to 36 inches
A horizon
Value - 3 to 5 dry, 2 or 3 moist
Chroma - 1 through 3 dry or moist
Reaction - neutral or slightly alkaline
Bt horizons
Value - 4 to 6 dry, 2 to 5 moist
Chroma - 2 to 4 dry or moist
Reaction - neutral to moderately alkaline
Bkq horizons
Value - 5 to 8 dry, 4 to 6 moist
Chroma - 2 or 3 dry or moist
Textures - very gravelly loam or extremely gravelly loam
COMPETING SERIES: These are the Acord and Datwyler series. Datwyler soils have hue of 7.5YR to 2.5YR in the subsoil. Acord soils lack the lime and silica concentrations in the lower part of the subsoil.
GEOGRAPHIC SETTING: Challis soils are on mountains and have slopes of 20 to 50 percent. Elevations range from 4,800 to 6,500 feet. The soils formed in slope alluvium from mixed sources. The average annual temperature is 37 to 42 degrees F. and the average annual precipitation is about 12 to 16 inches. The frost-fee period is 60 to 95 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cronks and Venum series. Cronks soils are on foothills and mountains and have an aridic moisture regime. Venum soils are on mountains, ridges and foothills, lack a mollic epipedon and have an aridic moisture regime.
DRAINAGE AND PERMEABILITY: Well drained; very rapid runoff; slow permeability.
USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. Native vegetation is threetip sagebrush, Idaho fescue, bluebunch wheatgrass, Sandberg bluegrass and Nevada bluegrass.
DISTRIBUTION AND EXTENT: South central Idaho; MLRA 12. They are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Custer County, Idaho, 1999.
REMARKS: Diagnostic features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 12 inches (A and Bt1 horizon)
Argillic horizon - The zone from 4 to 23 inches (Bt1 and Bt2 horizons)
Calcic features - The zone from 23 to 60 inches (Bkq horizons)
Particle-size control section - The zone from 4 to 23 inches (Bt horizons)
Xeric Moisture regime