LOCATION DERWELL IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Durinodic Xeric Haplocalcids
TYPICAL PEDON: Derwell gravelly very fine sandy loam--on a 1 percent smooth, south aspect at 6,560 feet elevation in rangeland. (Colors are for dry soil unless otherwise noted. When described on August 7, 1985, the soil was dry throughout.)
A--0 to 2 inches; pale brown (10YR 6/3) gravelly very fine sandy loam, brown (10YR 4/3) moist; moderate medium platy structure; soft, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots; many very fine and fine interstitial pores; 15 percent pebbles; strongly effervescent; slightly alkaline (pH 7.8); clear smooth boundary. (1 to 4 inches thick)
Bk1--2 to 9 inches; light yellowish brown (10YR 6/4) very fine sandy loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots; many very fine and fine interstitial pores; 10 percent pebbles; few lime coatings less than 1 mm thick on undersides of some coarse fragments; violently effervescent, moderately alkaline (pH 7.9); clear smooth boundary. (4 to 8 inches thick)
Bk2--9 to 15 inches; very pale brown (10YR 7/3) sandy loam, light yellowish brown (10YR 6/4) moist; moderate medium platy structure; hard, firm, nonsticky and nonplastic; common fine and few medium roots on structure plates; common very fine and fine interstitial pores; 10 percent pebbles; few lime coatings less than 1 mm thick on undersides of some coarse fragments; violently effervescent, slightly alkaline (pH 7.7); clear wavy boundary. (4 to 8 inches thick)
Bkq1--15 to 27 inches; very pale brown (10YR 7/3) very gravelly sandy loam, light yellowish brown (10YR 6/4) moist; moderate thick platy structure; hard, brittle or firm with 10 percent of horizon friable, nonsticky and nonplastic; few fine roots in fractures; common very fine and fine interstitial pores; 10 percent pebbles; 25 percent strongly cemented durinodes; krotovinas 4 to 6 inches in diameter filled with root mats and finer material; violently effervescent, slightly alkaline (pH 7.6); gradual wavy boundary. (5 to 15 inches thick)
Bkq2--27 to 38 inches; light gray (10YR 7/2) gravelly fine sandy loam, light yellowish brown (10YR 6/4) moist; massive; slightly hard, friable, nonsticky and nonplastic; common very fine and fine interstitial pores; 15 percent pebbles; few lime coatings less than 1 mm thick on undersides of some coarse fragments; 10 percent strongly cemented durinodes; violently effervescent; neutral (pH 7.3); gradual wavy boundary. (5 to 15 inches thick)
Bkq3--38 to 45 inches; very pale brown (10YR 7/3) gravelly fine sandy loam, light yellowish brown (10YR 6/4) moist; massive; slightly hard, friable, nonsticky and nonplastic; many very fine and fine interstitial pores; 30 percent pebbles; lime and minor silica coatings 1 mm thick on undersides of coarse fragments; violently effervescent; slightly alkaline (pH 7.4); gradual wavy boundary. (5 to 15 inches thick)
2Bkq4--45 to 60 inches; multicolored extremely gravelly sand; single grain; loose; many fine interstitial pores; 65 percent pebbles; lime and minor silica coatings 1 mm thick on undersides of coarse fragments; krotovinas 4 to 6 inches in diameter filled with root mats and finer material; strongly effervescent; slightly alkaline (pH 7.7).
TYPE LOCATION: Custer County, Idaho; approximately 2 miles west of Chilly Butte, about 1300 feet north and 1200 feet west from the southeast corner of section 34, T.9N., R.21E.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 39 to 45 degrees F
Control section -
Clay content - 8 to 15 percent
Coarse fragments: 10 to 30 percent
Depth to calcic horizon - 1 to 4 inches with 20 to 40 percent calcium carbonate
Depth to durinodes - 10 to 20 inches
Depth to sand and gravel (2Bkq horizon) - 40 to 60 inches
A horizon
Value - 3 or 4 moist
Bk horizon
Value - 6 or 7 dry, 4 through 6 moist
Chroma - 3 or 4 dry
Texture - VFSL, SL, GR-SL
Coarse fragments - 10 to 20 percent
Reaction - slightly or moderately alkaline
Bkq1 horizon
Value - 7 or 8 dry, 6 or 7 moist
Chroma - 2 through 4 dry or moist
Texture - very gravelly SL
Coarse fragments - 5 to 20 percent
Percent durinodes - 20 to 35
Bkq horizon
Value - 6 or 7 dry, 5 through 7 moist
Chroma - 2 or 3 dry, 3 or 4 moist
Texture - GR-FSL, GRV-SL
Coarse fragments - 15 to 50 percent
Bkq2 and Bkq3 horizon
Value - 6 or 7 dry, 4 to 6 moist
Chroma - 3 or 4 moist and dry
Coarse fragments - 60 to 80 percent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Derwell soils are on outwash fans and fan terraces. These soils formed in alluvium. Slopes are 1 to 6 percent. Elevations are 5,000 to 6,800 feet. The climate is cold and moist in winter and spring and dry in summer. Average annual precipitation is 8 to 11 inches. Average summer temperature is 60 to 62 degrees F. Average annual temperature is 37 to 44 degrees F. Frost-free period is 45 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Packmo and Zer soils. Packmo soils are on outwash fans and fan terraces and have loamy-skeletal control sections. Zer soils are on mountains and fan terraces and have loamy-skeletal control sections.
DRAINAGE AND PERMEABILITY: Well drained. Slow runoff; moderate over very rapid permeability.
USE AND VEGETATION: Rangeland. The natural vegetation is Wyoming big sagebrush and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: East-central Idaho. These soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Custer County, Idaho, 1999.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon
Durinodic - the zone from 15 to 27 inches (the Bkqm horizon) has over 20 percent strongly cemented durinodes in a brittle matrix.
Calcic horizon - The zone from 2 to 45 inches.