LOCATION NORTHFORK IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Pachic Ultic Haploxerolls
TYPICAL PEDON: Northfork fine gravelly sandy loam, forested -- on a west-facing slope of 70 percent at 4,900 feet elevation. When described on September 15, 1994, the soil was dry throughout. (Colors are for air-dry soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed forest litter.
A1--1 to 4 inches; very dark grayish brown (10YR 3/2) fine gravelly sandy loam, very dark brown (10YR 2/2) moist; weak medium platy structure parting to moderate fine granular; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, common medium and coarse, few very coarse roots; many very fine and fine irregular pores; 20 percent fine gravel; slightly acid (pH 6.4); clear smooth boundary. (2 to 10 inches thick)
A2--4 to 14 inches; very dark grayish brown (10YR 3/2) fine gravelly sandy loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure parting to moderate fine granular; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, common medium and coarse, few very coarse roots; many very fine and fine irregular pores; 25 percent fine gravel; slightly acid (pH 6.5); gradual wavy boundary. (0 to 20 inches thick)
Bw1--14 to 44 inches; dark grayish brown (10YR 4/2) fine gravelly sandy loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium, coarse and very coarse roots; many very fine and fine irregular pores; 30 percent fine gravel; slightly acid (pH 6.3); clear wavy boundary. (15 to 35 inches thick)
Bw2--44 to 56 inches; brown (10YR 4/3) fine gravelly sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; common very fine and fine, few medium roots; many very fine and fine irregular pores; 30 percent fine gravel; slightly acid (pH 6.2); clear wavy boundary. (10 to 35 inches thick)
Bw3--56 to 66 inches; dark yellowish brown (10YR 4/4) very gravelly sandy loam, dark yellowish brown (10YR 3/4) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; few very fine, fine and medium roots; many very fine and fine irregular pores; 30 percent fine gravel, 5 percent cobbles; slightly acid (pH 6.1).
TYPE LOCATION: Boise County, Idaho; about 6 miles east of Horseshoe Bend; 1,800 feet south and 2,300 feet east of the northwest corner of section 22, T.7 N., R.3 E.; USGS Harris Creek Summit Quadrangle; Latitude - 43 degrees, 55 minutes, 54 seconds N. and Longitude - 116 degrees, 05 minutes, 19 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 20 to 50 inches
Depth to bedrock - greater than 60 inches
Base saturation - 50 to 75 percent in some part between 10 and 30 inches
Particle-size control section - 8 to 15 percent clay; 5 to 35 percent rock fragments
Moisture control section - dry 45 to 75 consecutive days following the summer solstice
Average annual soil temperature - 42 to 47 degrees F.
A horizon
Value - 3 through 5 dry, 2 or 3 moist
Chroma - 1 through 3 dry or moist
Rock fragments - 10 to 35 percent gravel
Reaction - slightly acid or neutral
Bw1 horizon
Value - 4 or 5 dry, 3 or 4 moist
Chroma - 2 or 3 dry or moist
Texture - SL or COSL
Clay content - 8 to 15 percent
Rock fragments - 0 to 10 percent cobbles, 5 to 35 percent gravel and 5 to 35 percent total
Reaction - moderately acid or slightly acid
Bw2 and Bw3 horizons
Hue - 10YR or 2.5Y
Value - 4 through 7 dry, 3 through 5 moist
Chroma - 3 or 4 dry or moist
Texture - SL, COSL or LCOS
Clay content - 5 to 15 percent
Rock fragments - 0 to 10 percent cobbles, 15 to 55 percent gravel and 15 to 60 percent total
Reaction - moderately acid or slightly acid
C horizons occur in some pedons
COMPETING SERIES: These are the Moonstone and Riceton series. Moonstone soils are moderately deep to a paralithic contact. Riceton soils do not have an O horizon, are dry 75 to 90 consecutive days, and have stratified sand and gravel alluvium at 40 to 60 inches.
GEOGRAPHIC SETTING: Northfork soils are on mountain slopes and canyon walls at elevations of 2,750 to 6,900 feet. These soils formed in colluvium from granitic rocks. Slopes range from 15 to 90 percent. The average annual precipitation is 22 to 36 inches. The average annual temperature is 40 to 45 degrees F. The frost-free period is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Charters, Crumley, Shirts and Zimmer soils. Charters soils are not pachic. Crumley soils are loamy-skeletal. Shirts soils are moderately deep to a Cr horizon. Zimmer soils are shallow to bedrock. Charters and Crumley soils are on similar geomorphic positions. Shirts and Zimmer soils are on convex positions.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; medium to very rapid runoff; moderately rapid permeability.
USE AND VEGETATION: Northfork soils are used mainly for timber production, woodland grazing and wildlife habitat. Native vegetation is Douglas-fir, ponderosa pine, mallow ninebark, white spirea and mountain snowberry.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 43b. Northfork 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 1 to 44 inches (A1, A2, and Bw1 horizons)
Cambic horizon - zone from 56 to 66 inches (Bw3 horizon). Although the zone from 44 to 56 inches (Bw2 horizon) has <1% OM, it is not part of the cambic due to mollic colors.
Particle-size control section - zone from 10 to 40 inches
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.