LOCATION TRIPOD ID

Established Series
Rev. DJT/ALH/RWL
06/2011

TRIPOD SERIES

The Tripod series consists of very deep, excessively drained soils formed in colluvium from granitic rocks mixed with volcanic ash in the upper part. Slopes are 4 to 90 percent in mountains and canyons. The mean annual precipitation is about 31 inches and the mean annual temperature is about 41 degrees F.

TAXONOMIC CLASS: Sandy-skeletal, isotic, frigid Vitrandic Humixerepts

TYPICAL PEDON: Tripod fine gravelly ashy coarse sandy loam, forested -- on a north-facing slope of 77 percent at 4,700 feet elevation. When described on July 7, 1998, the soil was moist throughout. (Colors are for air-dry soil unless otherwise noted.)

Oi--0 to 1 inch; slightly decomposed forest litter.

Al--1 to 6 inches; dark grayish brown (10YR 4/2) fine gravelly ashy coarse sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and slightly plastic; many very fine and fine, common medium and coarse roots; many very fine, fine, medium and coarse irregular pores; 20 percent fine gravel; neutral (pH 6.6); gradual smooth boundary.

A2--6 to 13 inches; brown (10YR 5/3) fine gravelly ashy coarse sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine and fine, common medium and coarse roots; many very fine, fine, medium and coarse irregular pores; 25 percent fine gravel, 5 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (combined A horizon - 10 to 20 inches thick)

2AC--13 to 23 inches; light brownish gray (10YR 6/2) very cobbly loamy coarse sand, dark grayish brown (2.5Y 4/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, common medium and coarse roots; many very fine, fine, medium and coarse irregular pores; 25 percent gravel, 30 percent cobbles; slightly acid (pH 6.2); gradual wavy boundary. (0 to 24 inches thick)

2Cl--23 to 50 inches; light gray (10YR 7/2) very gravelly coarse sand, grayish brown (2.5Y 5/2) moist; single grain; loose, nonsticky and nonplastic; few very fine, fine, medium and coarse roots; common very fine, fine, medium and-coarse irregular pores; 40 percent gravel, 10 percent cobbles; moderately acid (pH 5.9); clear smooth boundary. (0 to 30 inches thick)

2C2--50 to 60 inches; white (10YR 8/1) very cobbly coarse sand, gray (2.5Y 6/1) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine, fine, medium, and coarse roots; common very fine, fine, medium and coarse irregular pores; 30 percent gravel, 20 percent cobbles; moderately acid (pH 5.9).

TYPE LOCATION: Boise County, Idaho; about 2.5 miles northwest of Crouch; 1,350 feet south and 400 feet west of the northeast corner of section 6, T.9 N., R.4 E.; USGS Packer John Mountain Quadrangle; Latitude - 44 degrees, 08 minutes, 41 seconds N. and Longitude - 116 degrees, 01 minute, 09 seconds W.; NAD 83.

RANGE IN CHARACTERISTICS:
Umbric and vitrandic feature thickness - 10 to 20 inches
Depth to bedrock - 60 inches or more
Particle-size control section - 2 to 7 percent clay; 35 to 75 percent rock fragments
Moisture control section - dry 45 to 75 consecutive days following the summer solstice
Average annual soil temperature - 41 to 46 degrees F.

A horizon
Hue - 10YR or 2.5Y
Value - 3 through 5 dry, 2 or 3 moist
Chroma - 1 through 3 dry or moist
Texture - ASHY-SL or ASHY-COSL
Rock fragments - 15 to 35 percent fine gravel, 0 to 5 percent cobbles and 15 to 35 percent total
Reaction - slightly acid or neutral
Volcanic glass content - 5 to 20 percent
Acid oxalate extract Al+1/2 Fe - 0.4 to 1.0 percent

2C horizon
Hue - 10YR or 2.5Y
Value - 5 through 8 dry, 4 through 6 moist
Chroma - 1 through 4 dry or moist
Texture - LS, LCOS, S or COS
Clay content - 0 to 4 percent
Rock fragments - 0 to 25 percent stones, 5 to 30 percent cobbles, 15 to 50 percent gravel and 35 to 75 percent total
Reaction - moderately acid or slightly acid

COMPETING SERIES: This is the Pajo series. Pajo soils are 20 to 40 inches deep to bedrock.

GEOGRAPHIC SETTING: Tripod soils are on mountain slopes and canyon walls at elevations of 3,200 to 7,000 feet. These soils formed in colluvium from granitic rocks mixed with volcanic ash in the upper part. Slopes range from 4 to 90 percent. The average annual precipitation is 26 to 36 inches. The average annual temperature is 39 to 44 degrees F. The frost-free period is 60 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kosh, Packerjohn, Shirts and competing Pajo soils. Kosh soils are shallow. Packerjohn soils are sandy. Shirts soils are coarse-loamy and moderately deep. Kosh and Shirts soils are on convex summits and shoulders. Packerjohn and Pajo soils are on similar geomorphic positions.

DRAINAGE AND PERMEABILITY: Excessively drained; slow to rapid runoff; rapid permeability.

USE AND VEGETATION: Tripod soils are used mainly for timber production and wildlife habitat. Native vegetation is grand fir, Douglas-fir, thinleaf (blue) huckleberry, mountain maple, mallow ninebark and white spirea.

DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 43B. Tripod 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:
Umbric epipedon and vitrandic feature - zone from the mineral soil surface to 13 inches (Al and A2 horizons)
Particle-size control section - zone from 11 to 41 inches
Soil moisture regime - xeric

All depths related to diagnostic horizons and features listed in the range of characteristics are from the top of the first mineral horizon.

National Cooperative Soil Survey
U.S.A.