LOCATION FLOODWOOD IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, isotic, frigid Andic Hapludalfs
TYPICAL PEDON: Floodwood ashy silt loam, forest, on a north-facing slope of 55 percent at 3,300 feet elevation. When described on July 10, 1984, the soil was moist throughout. (Colors are for dry soil unless otherwise stated.)
Oi--0 to 1 inch; slightly decomposed needles, leaves and twigs.
Oe--1 to 2 inches; decomposed organic matter. (O horizons 1 to 2 inches thick)
A--2 to 7 inches; brown (10YR 5/3) ashy silt loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure parting to weak fine granular; soft, very friable, nonsticky and slightly plastic; many very fine and fine roots; many very fine and fine tubular pores; common fine, rounded iron and manganese concretions; neutral (pH 6.8); clear wavy boundary. (2 to 6 inches thick)
Bw--7 to 14 inches; light yellowish brown (10YR 6/4) ashy silt loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; common very fine, fine, medium and few coarse roots; common very fine and fine tubular pores; common fine, rounded iron and manganese concretions; neutral (pH 6.8); clear wavy boundary. (5 to 10 inches thick)
2Bt1--14 to 31 inches; very pale brown (10YR 7/4) loam, yellowish brown (10YR 5/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine and medium roots; common very fine and fine tubular pores; common faint clay films on faces of peds and lining pores; 5 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (12 to 17 inches thick)
2Bt2--31 to 40 inches; very pale brown (10YR 7/4) loam, yellowish brown (10YR 5/4) moist; moderate medium and coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular and irregular pores; common faint clay films on faces of peds and few distinct clay films lining pores; wavy clayey band 1 cm thick in lower part of horizon; common medium iron stains; 10 percent gravel; moderately acid (pH 5.6); clear wavy boundary. (7 to 9 inches thick)
2BC--40 to 44 inches; pale yellow (2.5Y 7/4) fine sandy loam, light olive brown (2.5Y 5/4) moist; weak coarse subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; few very fine roots; many very fine and fine irregular pores; few faint clay films lining pores; 10 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (0 to 12 inches thick)
2C1--44 to 56 inches; light yellowish brown (2.5Y 6/4) gravelly loamy fine sand, olive brown (2.5Y 4/4) moist; massive; slightly hard, friable, nonsticky and nonplastic; few very fine roots; many very fine and fine irregular pores; three discontinuous yellow (10YR 7/6) clayey bands 1 to 3 cm thick in lower part of horizon; 10 percent gravel, 5 percent cobbles; slightly acid (pH 6.5); clear wavy boundary. (11 to 13 inches thick)
2C2--56 to 62 inches; very pale brown (10YR 8/4) gravelly fine sandy loam, yellow (10YR 7/6) moist; massive; slightly hard, friable, nonsticky and nonplastic; few very fine roots; many very fine irregular pores; 10 percent gravel, 5 percent cobbles; moderately acid (pH 6.0).
TYPE LOCATION: Shoshone County, Idaho; about 17 miles east of Clarkia, about 600 feet east and 2200 feet north of the southwest corner of Section 25, T. 42 N., R. 4 E.
RANGE IN CHARACTERISTICS:
Soil moisture - usually dry for 10 to 20 consecutive days in mid-August to September, moist in the fall through mid-summer. Udic moisture regime.
Average annual soil temperature - 39 to 46 degrees F.
Average summer soil temperature - 48 to 50 degrees F. with an 0 horizon. Frigid temperature regime.
Depth to bedrock - greater than 60 inches
Solum thickness - 40 to 50 inches
Volcanic ash mantle - 9 to 14 inches
Volcanic glass content in the 0.02 to 2.0 mm fraction - 5 to 65 percent
Acid-oxalate extractable Al plus 1/2 Fe - 1.0 to 3.0 percent
A horizon
Hue - 7.5YR or 10YR
Value - 4 to 6 dry, 2 to 4 moist
Chroma - 2 to 4 dry or moist
Textures - ASHY-SIL, ASHY-L
Clay content - 3 to 10 percent
Rock fragments - 0 to 15 percent gravel
Bulk density - 0.65 to 0.95 g/cc
Reaction - strongly acid to neutral
Bw horizon
Hue - 7.5YR or 10YR
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Textures - ASHY-SIL, ASHY-L
Clay content - 3 to 10 percent
Rock fragments - 0 to 15 percent gravel
Bulk density - 0.65 to 1.20 g/cc
Reaction - very strongly acid to neutral
2Bt horizon
Hue - 7.5YR or 10YR
Value - 5 to 8 dry, 3 to 6 moist
Chroma - 3 to 6 dry or moist
Texture - FSL, VFSL, L, GR-L, SIL, GR-SIL, CB-SIL, CB-L, GR-CL
Clay content - 15 to 28 percent (weighted average greater than 18 percent)
Rock fragments - 0 to 30 percent gravel, 0 to 15 percent cobbles, 0 to 30 percent total rock fragment content
Base saturation - 35 to 50 percent
Reaction - very strongly acid to slightly acid
2BC horizon
Hue - 7.5YR to 2.5Y
Value - 6 or 7 dry, 4 to 6 moist
Chroma - 4 or 6 dry or moist
Textures - L, SL, FSL
Clay content - 12 to 20 percent
Rock fragments - 0 to 10 percent gravel
Reaction - very strongly acid to moderately acid
2C Horizon
Hue - 7.5YR to 2.5Y
Value - 5 to 8 dry, 4 to 7 moist
Chroma - 3 to 8 dry or moist
Texture - LS, GR-LFS, LFS, FSL, GR-FSL, VFSL, GR-VFSL, COSL, L
Clay content - 0 to 19 percent
Rock fragments - 2 to 34 percent gravel, 0 to 10 percent cobbles, 0 to 34 percent total rock fragments
Reaction - very strongly acid to slightly acid
COMPETING SERIES: This is the Lakestarr series. Lakestarr soils have a densic contact at 40 to 60 inches.
GEOGRAPHIC SETTING: Floodwood soils are on north, east, and west facing aspects of mountain slopes, ridges and foothills. These soils formed in material weathered from anorthosite, schist, and gneiss, with a mantle of volcanic ash. Slopes are 10 to 65 percent. Elevations are 1,600 to 4,800 feet. The climate is cool, humid with warm, moist summers and cool, wet winters. The average annual precipitation is 30 to 65 inches and the average annual air temperature is 38 to 45 degrees F. The frost-free season is 50 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Garveson, Keeler (T), and Odonnell (T) soils. Garveson soils are on canyon slopes and are ashy over sandy or sandy-skeletal. Keeler soils are on south-facing convex slopes and have a low content of volcanic ash. Odonnell soils are on concave toe slopes, and have E horizons and are moderately well drained.
DRAINAGE AND PERMEABILITY: Well drained, rapid to very rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for timber production, recreation, wildlife habitat, and watershed. Potential natural vegetation is mainly western redcedar, western white pine, grand fir, Douglas-fir, and western larch, with an understory of oakfern, queencup beadlily, goldthread, bunchberry dogwood, American maidenhair fern, common prince's pine, Oregon fairybells, starry-false-Solomon's-seal, wild ginger, and arrowleaf groundsel.
DISTRIBUTION AND EXTENT: Northern Idaho. This soil is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Shoshone County, Idaho, 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 2 to 7 inches (A horizon).
Argillic horizon - the zone from 14 to 40 inches (2Bt1, 2Bt2 horizons).
Volcanic ash mantle - the zone from 2 to 14 inches (A and Bw horizons).
Particle-size control section - the zone from 14 to 34 inches (2Bt1 horizon and part of the 2Bt2 horizon).