LOCATION TIMBERBUTTE IDEstablished Series
TAXONOMIC CLASS: Ashy-skeletal over loamy-skeletal, glassy over isotic, frigid Humic Vitrixerands
TYPICAL PEDON: Timberbutte very gravelly ashy silt loam, forested -- on a north-facing slope of 55 percent at 4,320 feet elevation. When described on July 21, 1992, the soil was dry throughout. (Colors are for air-dry soil unless otherwise noted.)
Oi--0 to 2 inches; undecomposed and partially decomposed forest litter.
A--2 to 12 inches; dark grayish brown (10YR 4/2) very gravelly ashy silt loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine and medium, few coarse roots; many very fine, fine and medium irregular and tubular pores; 40 percent gravel; slightly acid (pH 6.4); diffuse wavy boundary. (7 to 12 inches thick)
Bw1--12 to 21 inches; brown (10YR 5/3) very gravelly ashy silt loam, dark brown (10YR 3/3) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine and medium, few coarse roots; many very fine, fine and medium irregular and tubular pores; 45 percent gravel and 10 percent cobbles; slightly acid (pH 6.3); gradual wavy boundary. (5 to 15 inches thick)
Bw2--21 to 29 inches; brown (10YR 5/3) very gravelly ashy loam, dark brown (10YR 3/3) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine and medium, few coarse roots; many very fine, fine and medium irregular and tubular pores; 45 percent gravel and 10 percent cobbles; slightly acid (pH 6.3); gradual wavy boundary. (0 to 10 inches thick)
2Bw3--29 to 39 inches; brown (10YR 5/3) extremely gravelly sandy loam, brown (10YR 4/3) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine and medium, few coarse roots; many very fine, fine and medium irregular and tubular pores; 55 percent gravel and 10 percent cobbles; moderately acid (pH 6.0); gradual wavy boundary. (5 to 15 inches thick)
2C--39 to 60 inches; light brownish gray (10YR 6/2) extremely gravelly sandy loam, brown (10YR 5/3) moist; single grain; loose, nonsticky and slightly plastic; many very fine, fine and medium, few coarse roots; many very fine, fine and medium irregular and tubular pores; 65 percent gravel and 15 percent cobbles; moderately acid (pH 6.0).
TYPE LOCATION: Boise County, Idaho; about 9 miles north and 2 miles west of Horseshoe Bend; 600 feet north and 300 feet west of the southeast corner of section 5, T.8 N., R.2 E.; Latitude - 44 degrees, 03 minutes, 12 seconds N. and Longitude - 116 degrees, 14 minutes, 12 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 20 to 30 inches
Depth to bedrock - greater than 60 inches
Base saturation by sum of cations - 50 to 75 percent in the upper 30 inches
Particle-size control section - 7 to 12 percent clay; 60 to 80 percent rock fragments
Moisture control section - dry 45 to 75 consecutive days following the summer solstice
Average annual soil temperature - 45 to 47 degrees F.
Volcanic ash mantle
Thickness - 14 to 30 inches
Volcanic glass content - 30 to 50 percent
Acid oxalate extract Al+1/2Fe - 0.4 to 1.2 percent
15-bar water retention on air-dried samples - 10 to 12 percent
A horizon
Value - 3 or 4 dry, 2 or 3 moist
Chroma - 1 or 2 dry or moist
Rock fragments - 35 to 60 percent gravel
Bw horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture - ASHY-L or ASHY-SIL
Clay content - 7 to 12 percent
Rock fragments - 5 to 10 percent cobbles, 30 to 50 percent gravel and 35 to 60 percent total
2Bw horizon
Value - 4 or 5 dry, 3 or 4 moist
Chroma - 2 or 3 dry or moist
Texture - L or SL
Clay content - 7 to 12 percent
Rock fragments - 5 to 15 percent cobbles, 50 to 65 percent gravel and 60 to 75 percent total
Reaction - moderately acid or slightly acid
2C horizon
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 2 or 3 dry or moist
Texture - L or SL
Clay content - 5 to 10 percent
Rock fragments - 5 to 15 percent cobbles, 55 to 70 percent gravel and 60 to 85 percent total
Reaction - moderately acid or slightly acid
COMPETING SERIES: These are the Fryrear, McCumber (T), Pipp, Silentcone, and Yapoah series. Fryrear soils are 40 to 60 inches deep to lithic bedrock and are dry for more than 90 consecutive days. McCumber soils have an umbric epipedon 10 to 14 inches thick and andic properties throughout. Pipp soils are 40 to 60 inches deep to a lithic contact. Silentcone soils are 20 to 30 inches deep to a lithic contact and are dry for 90 to 100 consecutive days. Yapoah soils have a mollic epipedon 10 to 15 inches thick, do not have a B horizon and have 5 to 8 percent field estimated clay with ashy loamy sand texture throughout the particle-size control section.
GEOGRAPHIC SETTING: Timberbutte soils are on north and east-facing volcanic cone slopes at 4,100 to 5,050 feet. These soils formed in colluvium weathered from welded tuff mixed with volcanic ash in the upper part. Slopes range from 35 to 65 percent. The average annual precipitation is 26 to 30 inches. The average annual temperature is 43 to 45 degrees F. The frost-free period is 75 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hovelton and McDaniel soils. Hovelton and McDaniel soils are on south and west-facing volcanic cone slopes and have argillic horizons.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; rapid to very rapid runoff; moderate permeability.
USE AND VEGETATION: Timberbutte soils are used mainly for timber production. Native vegetation is Douglas-fir, ponderosa pine and mallow ninebark.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 43b. Timberbutte soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise County Area, Idaho, Parts of Ada and Boise Counties, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon - zone from 2 to 29 inches (A, Bw1 and Bw2 horizons)
Andic soil properties - zone from 2 to 29 inches (A, Bw1 and Bw2 horizons)
Cambic horizon - zone from 29 to 39 inches (Bw3 horizon)
Particle-size control section - zone from 2 to 42 inches; 2 to 29 inches ashy-skeletal and 29 to 42 inches loamy-skeletal
Soil moisture regime - xeric
All depths to diagnostic horizons and features within the range of characteristics are measured from the top of the first mineral horizon.
ADDITIONAL DATA: Reference Sample No. S92ID-015-001 (NSSL Sample No. 93P506).