LOCATION FLATSTONE IDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, active Vitrandic Palecryalfs
TYPICAL PEDON: Flatstone silt loam, on a 12 percent convex sideslope in an area of lodgepole pine/pinegrass community type at an elevation of 6,370 feet. (Colors are for dry soil unless otherwise stated.)
0i--0 to 1 inch; forest litter; slightly decomposed needles, twigs and cones. (0 to 2 inches thick)
A--1 to 6 inches; grayish brown (10YR 5/2) ashy silt loam, dark brown (10YR 3/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots; many fine irregular pores; 10 percent pebbles; moderately acid (pH 5.6); clear smooth boundary. (3 to 6 inches thick)
E1--6 to 14 inches; pale brown (10YR 6/3) gravelly ashy silt loam, dark grayish brown (10YR 4/2) moist; moderate fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine and fine and few medium roots; common very fine irregular and few fine tubular pores; 20 percent pebbles, 5 percent cobbles; moderately acid (pH 5.6); clear wavy boundary.
E2--14 to 35 inches; light gray (10YR 7/2) extremely stony ashy silt loam, grayish brown (10YR 5/2) moist; weak fine subangular blocky structure; soft, friable, nonsticky and nonplastic; common very fine and fine and few medium roots; few very fine irregular and few fine tubular pores; 10 percent pebbles, 30 percent cobbles, 40 percent stones; moderately acid (pH 5.6); gradual wavy boundary. (combined thickness of E horizons is 20 to 30 inches)
E/B--35 to 45 inches; 60 percent light gray (10YR 7/2) extremely cobbly ashy loam, dark grayish brown (10YR 4/2) moist E material; 40 percent light brownish gray (10YR 6/2), dark yellowish brown (10YR 4/4) moist B material; weak coarse subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine tubular pores; 30 percent pebbles, 40 percent cobbles, 10 percent stones; moderately acid (pH 5.6); clear wavy boundary. (10 to 15 inches thick)
2Bt/E--45 to 55 inches; 70 percent pale brown (10YR 6/3) cobbly ashy loam, dark yellowish brown (10YR 4/4) moist B material; 30 percent light gray (10YR 7/1), dark grayish brown (10YR 4/2) moist E material; moderate coarse prismatic structure parting to moderate medium subangular blocky; slightly hard, firm, sticky and plastic; few fine roots; common fine tubular pores; common fine dark yellowish brown (10YR 4/6) moist clay films on faces of peds and bridging sand grains; 10 percent pebbles, 10 percent cobbles, 5 percent stones; moderately acid (pH 5.8); clear wavy boundary. (5 to 20 inches thick)
2Bt--55 to 67 inches; pale brown (10YR 6/3) cobbly ashy clay loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, firm, sticky and plastic; few fine roots; common fine tubular pores; common fine dark yellowish brown (10YR4/4) moist clay films on faces of peds and bridging sand grains; 10 percent pebbles, 10 percent cobbles, 5 percent stones; slightly acid (pH 6.4).
TYPE LOCATION: Fremont County, Idaho; approximately 28 miles north of Ashton; 500 feet south and 2000 feet east of the northwest corner of sec. 9, T.13N., R.43E. Latitude - 44 degrees, 28 minutes, 10 seconds North; Longitude -111 degrees, 23 minutes, 10 seconds West.
RANGE IN CHARACTERISTICS:
Depth to argillic horizon - 40 to 50 inches.
Mean annual soil temperature - 39 to 42 degrees F.
Mean summer soil temperature - 42 to 46 degrees F.
Moisture control section - between 4 and 12 inches. Dry throughout the moisture control section for 30 to 45 consecutive days during the four months following the summer solstice.
Particle-size control section rock fragments - averages 35 to 80 percent.
Volcanic glass content - 5 to 30 percent in the 0.02 to 2.0 mm fraction.
Ammonium oxalate extractable Al plus 1/2 Fe - 0.1 to 1.0 percent.
Phosphate retention - 20 to 50 percent.
A horizon - Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Clay content: 10 to 14 percent
Rock fragment content: 0 to 10 percent pebbles
Base saturation by ammonium acetate: 30 to 50 percent
Reaction: moderately acid (pH 5.6 to 6.0)
E1 horizon - Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3 dry or moist
Clay content: 10 to 14 percent
Rock fragment content: 15 to 35 percent
Pebbles: 10 to 20 percent
Cobbles: 5 to 15 percent
Stones: 0 to 5 percent
Base saturation by ammonium acetate: 30 to 80 percent
Reaction: moderately acid (pH 5.6 to 6.0)
E2 horizon - Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3 dry or moist
Texture: silt loam or loam
Clay content: 10 to 14 percent
Rock fragment content: 35 to 80 percent
Pebbles: 5 to 30 percent
Cobbles: 15 to 40 percent
Stones: 10 to 40 percent
Base saturation by ammonium acetate: 30 to 80 percent
Reaction: moderately acid (pH 5.6 to 6.0)
E/B horizon - Value: E part 6 or 7 dry, 4 to 6 moist
B part 5 or 6 dry, 4 or 5 moist
Chroma: E part 1 through 3 dry or moist
B part 2 through 4 dry or moist
Texture: silt loam or loam
Clay content: 10 to 14 percent
Rock fragment content: 35 to 80 percent
Pebbles: 5 to 30 percent
Cobbles: 15 to 40 percent
Stones: 10 to 40 percent
Base saturation by ammonium acetate: 30 to 80 percent
Reaction: moderately acid (pH 5.6 to 6.0)
Other: 50 to 85 percent E material and 15 to 50 percent B material
2Bt/E horizon - Value: B part 5 or 6 dry, 4 or 5 moist
E part: 6 or 7 dry, 5 or 6 moist
Chroma: B part 2 through 4 dry or moist
E part: 1 through 3 dry or moist
Texture: loam or clay loam
Clay content: 14 to 30 percent
Rock fragment content: 15 to 35 percent
Pebbles: 0 to 15 percent
Cobbles: 10 to 20 percent
Stones: 0 to 10 percent
Base saturation by ammonium acetate: 60 to 100 percent
Reaction: moderately acid or slightly acid (pH 5.6 to 6.5)
Other: 50 to 85 percent B material and 15 to 50 percent E material
2Bt horizon - Value: 5 or 6 dry and 4 or 5 moist
Chroma: 2 through 4 dry or moist
Texture: loam or clay loam
Clay content: 14 to 30 percent
Rock fragment content: 15 to 35 percent
Pebbles: 0 to 15 percent
Cobbles: 10 to 20 percent
Stones: 0 to 10 percent
Base saturation by ammonium acetate: 60 to 100 percent
Reaction: moderately acid or slightly acid (pH 5.6 to 6.5)
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Flatstone soils occur on disected tablelands and caldera floors. Slopes range from 4 to 15 percent. Elevation ranges from 5,900 to 7,000 feet. These soils formed in local alluvium and residuum derived from loess, volcanic ash and rhyolite tuff. The mean annual precipitation is 25 to 35 inches. The mean annual air temperature is 37 to 40 degrees F. The frost-free season is less than 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Islandpark and Koffgo series. Koffgo soils are intermixed with the Flatstone soils. They lack argillic horizons. Islandpark soils are on nearby positions. They have less than 15 percent fine sand or coarser throughout the profile.
DRAINAGE AND PERMEABILITY: Well drained; runoff is slow to medium; permeability is moderate.
USE AND VEGETATION: Used for timber production, recreation, and wildlife habitat. Principal vegetation is lodgepole pine and pinegrass.
DISTRIBUTION AND EXTENT: Eastern Idaho in the Islandpark area. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Targhee National Forest, Fremont County, Idaho, 1997.
REMARKS: Location coordinates determined by Global Positioning System.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the soil surface to 35 inches (Oi, A, E1 and E2 horizons)
Albic horizon - the zone from 6 to 35 inches (E1 and E2 horizons)
Glossic horizon - the zone form 35 to 55 inches (E/B and 2Bt/E horizons)
Argillic horizon - the zone from 45 to 67 inches (2Bt/E and 2Bt horizons)
Particle-size control section - the zone from 11 to 41 inches (E1, E2 and part of the E/B horizons)
Vitrandic subgroup feature - the zone from 1 to 67 inches (A, E1, E2, E/B, 2Bt/E and 2Bt horizons)
Temperature regime - cryic
Moisture regime - udic