LOCATION ZAN IDEstablished Series
TAXONOMIC CLASS: Sandy, isotic Vitrixerandic Humicryepts
TYPICAL PEDON: Zan fine gravelly ashy coarse sandy loam, forested -- on a northwest-facing slope of 50 percent at 6,400 feet elevation. When described on July 15, 1997, the soil moist throughout. (Colors are for air-dry soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed forest litter.
A1--1 to 3 inches; very dark grayish brown (10YR 3/2) fine gravelly ashy coarse sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, few medium and coarse roots; many very fine, fine and medium irregular pores; 15 percent fine gravel; moderately acid (pH 6.0); clear smooth boundary.
A2--3 to 14 inches; very dark grayish brown (10YR 3/2) fine gravelly ashy coarse sandy loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, few medium and coarse roots; many very fine, fine and medium irregular pores; 20 percent fine gravel; moderately acid (pH 5.8); gradual smooth boundary. (combined A horizon - 7 to 24 inches thick)
AB--14 to 24 inches; brown (10YR 4/3) fine gravelly ashy loamy coarse sand, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, few medium and coarse roots; many very fine, fine and medium irregular pores; 25 percent fine gravel; moderately acid (pH 5.8); clear smooth boundary. (4 to 20 inches thick)
Bw--24 to 35 inches; brown (10YR 5/3) fine gravelly ashy loamy coarse sand, dark olive brown (2.5Y 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, few medium and coarse roots; many very fine, fine and medium irregular pores; 20 percent fine gravel; moderately acid (pH 5.7); gradual wavy boundary. (6 to 16 inches thick)
2C--35 to 60 inches; light yellowish brown (2.5Y 6/3) very gravelly loamy coarse sand, olive brown (2.5Y 4/4) moist; single grain; loose, nonsticky and nonplastic; common very fine and fine roots; many very fine, fine and medium irregular pores; 35 percent gravel, 10 percent cobbles; moderately acid (pH 5.9).
TYPE LOCATION: Boise County, Idaho; about 7 miles east of Horseshoe Bend; 1,600 feet south and 2,500 feet east of the northwest corner of section 26, T.7 N., R.3 E.; USGS Harris Creek Summit Quadrangle; Latitude - 43 degrees, 55 minutes, 06 seconds N. and Longitude - 116 degrees, 04 minutes, 08 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Umbric epipedon thickness - 14 to 30 inches
Vitrandic properties thickness - 17 to 35 inches
Depth to bedrock - greater than 60 inches
Reaction - moderately acid or slightly acid
Particle-size control section - 2 to 8 percent clay; 15 to 35 percent rock fragments
Moisture control section - dry 45 to 60 consecutive days in the four months following the summer solstice
Average annual soil temperature - 37 to 40 degrees F.
Average summer soil temperature - 44 to 46 degrees F.
A horizon
Value - 3 through 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Rock fragments - 15 to 35 percent fine gravel
Base saturation (NH4OAc) - 30 to 50 percent
Volcanic glass content - 5 to 10 percent
Acid oxalate extract Al + 1/2 Fe - 0.4 to 1.0 percent
AB horizon
Hue - 10YR or 2.5Y
Value - 4 or 5 dry
Chroma - 2 or 3 dry or moist
Texture - ASHY-LCOS or ASHY-COSL
Clay content - 4 to 10 percent
Rock fragments - 15 to 35 percent fine gravel
Base saturation (NH40Ac) - 30 to 50 percent
Volcanic glass content - 5 to 10 percent
Acid oxalate extract Al + 1/2 Fe - 0.4 to 1.0 percent
Bw horizon
Hue - 10YR or 2.5Y
Value - 4 through 6 dry, 3 through 5 moist
Chroma - 3 or 4 dry or moist
Clay content - 2 to 8 percent
Rock fragments - 15 to 35 percent fine gravel
2C horizon
Hue - 10YR or 2.5Y
Value - 5 through 7 dry, 4 through 6 moist
Chroma - 3 through 6 dry or moist
Texture - LCOS or COS
Clay content - 2 to 5 percent
Rock fragments - 0 to 15 percent cobbles, 20 to 50 percent gravel and 20 to 60 percent total
COMPETING SERIES: There are no other series in this family. The Belsh and Montchief series in a closely related family are sandy-skeletal.
GEOGRAPHIC SETTING: Zan soils are on mountain slopes, ridges and canyon walls at elevations of 4,700 to 7,350 feet. These soils formed in colluvium from granitic rocks and volcanic ash. Slopes range from 4 to 90 percent. The average annual precipitation is 28 to 40 inches. The average annual temperature is 36 to 39 degrees F. The frost-free period is 30 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Belsh and Montchief soils. Belsh and Montchief soils are sandy-skeletal and on similar geomorphic positions.
DRAINAGE AND PERMEABILITY: Excessively drained; medium to rapid runoff; rapid permeability.
USE AND VEGETATION: Zan soils are used mainly for timber production, woodland grazing and wildlife habitat. Native vegetation is subalpine fir, Douglas-fir, mountain maple and thinleaf (blue) huckleberry.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 43b. Zan 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 - zone from the mineral soil surface to 24 inches (A1, A2 and AB horizons)
Vitrandic feature - zone from the mineral soil surface to 35 inches (Al, A2 AB, and Bw horizons)
Cambic horizon ( < 1.0 percent O.M.) - zone from 24 to 35 inches (Bw horizon)
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 measured from the top of the first mineral horizon.