LOCATION CULDESAC IDEstablished Series
TAXONOMIC CLASS: Ashy over loamy, mixed, superactive, frigid Alfic Vitrixerands
TYPICAL PEDON: Culdesac ashy silt loam - on a 12 percent north-facing slope at an elevation of 4,675 feet in forest. (Colors are for dry soil unless otherwise noted. When described on October 23, 1980, the soil was moist throughout.)
Oi--0 to 1 inch; undecomposed needles and twigs.
Oe--1 to 2 inches; decomposing needles and twigs.
A--2 to 5 inches; yellowish brown (10YR 5/4) ashy silt loam, dark brown (7.5YR 3/4) moist; weak medium and coarse platy structure parting to weak fine and medium subangular blocky; soft, very friable, nonsticky and slightly plastic; many very fine and fine roots; many very fine and fine irregular pores; slightly acid (pH 6.4); clear wavy boundary. (1 to 4 inches thick)
Bw1--5 to 12 inches; light yellowish brown (10YR 6/4) ashy silt loam, brown (7.5YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine and medium, and common coarse roots; many very fine and common fine irregular pores; slightly acid (pH 6.2); gradual wavy boundary.
Bw2--12 to 20 inches; light yellowish brown (10YR 6/4) ashy silt loam, strong brown (7.5YR 4/6) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine and medium, and common coarse roots; many very fine, and common fine irregular pores; slightly acid (pH 6.2); abrupt wavy boundary. (combined thickness of the Bw1 and Bw2 horizons is 12 to 18 inches)
2Btb1--20 to 27 inches; light yellowish brown (10YR 6/4) silty clay loam, brown (7.5YR 4/4) moist; weak fine prismatic structure parting to moderate fine subangular blocky; hard, firm, sticky and plastic; many medium and coarse, and common very fine and fine roots; many very fine and fine, and common medium irregular and many very fine tubular pores; common faint, and few distinct clay films lining pores and on faces of peds; few light yellowish brown (10YR 6/4) skeletans on faces of peds; 5 percent gravel; neutral (pH 6.6); clear smooth boundary.
2Btb2--27 to 43 inches; brown (7.5YR 5/4) silty clay loam, brown (7.5YR 4/4) moist; moderate fine and medium prismatic structure parting to moderate fine subangular blocky; hard, firm, sticky and plastic; common fine and medium roots; many very fine and fine, and common medium irregular and common very fine and fine tubular pores; many distinct clay films lining pores and on faces of peds; 5 percent gravel; common light yellowish brown (10YR 6/4) skeletans on faces of peds; slightly acid (pH 6.5); clear wavy boundary.
2Btb3--43 to 56 inches; brown (7.5YR 5/4) silty clay loam, brown (7.5YR 4/4) moist; moderate fine prismatic structure parting to common fine subangular blocky; very hard, firm, sticky, and plastic; few very fine and common fine and medium roots; many very fine and fine and common medium irregular, and common very fine and fine tubular pores; common faint and few distinct clay films lining pores and on faces of peds; 5 percent gravel; few light yellowish brown (10YR 6/4) skeletans on faces of peds; neutral (pH 6.6); clear wavy boundary. (combined thickness of the 2Btb1, 2Btb2, and 2Btb3 horizons is 24 to 42 inches)
2Btb4--56 to 60 inches; brown (7.5YR 5/4) clay loam, strong brown (7.5YR 4/6) moist; weak fine and medium prismatic structure parting to moderate fine and medium subangular blocky; very hard, firm, sticky and plastic; few very fine, fine, and medium roots; many very fine and fine, and common medium irregular pores; few distinct and common faint clay films lining pores and on faces of peds; 10 percent gravel; neutral (pH 6.6).
TYPE LOCATION: Lewis County, Idaho; about 3 miles east of Soldiers Meadow Reservoir, about 150 feet north and 2,200 feet east of the southwest corner of section 34, T. 33 N., R. 3 W.; USGS Winchester West quadrangle; Latitude - 46 degrees, 09 minutes, 07 seconds N. and Longitude - 116 degrees, 41 minutes, 34 seconds W.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 42 to 45 degrees F
Volcanic ash mantle
Thickness - 14 to 20 inches
Volcanic glass content in the 0.02 to 2.0 mm fraction - 20 to 45 percent
Acid-oxalate extractable Al plus 1/2 Fe - 0.5 to 2.0 percent
Bulk density - .75 to .95 g/cc
15-bar water retention on air dried samples - 8 to 12 percent
Particle-size control section, lower part (weighted averages)
Clay content - 28 to 35 percent
Gravel content - 0 to 5 percent
A horizon
Hue - 7.5YR or 10YR
Value - 4 or 5 dry, 2 through 4 moist
Chroma - 2 through 4, dry or moist
Reaction - moderately acid through neutral
Bw horizon
Hue - 7.5YR or 10YR moist
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 4 through 6, dry or moist
Fine gravel content - 0 to 10 percent
Reaction - moderately acid or slightly acid
2Btb horizon, upper part
Hue - 7.5YR or 10YR
Value - 4 through 6 dry, 3 or 4 moist
Chroma - 4 through 6, dry or moist
Gravel content - 0 to 10 percent
Clay content - 28 to 38 percent
Base saturation - 55 to 70 percent
Reaction - moderately acid through neutral
2Btb horizon, lower part
Hue - 7.5YR or 10YR
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 4 through 6, dry or moist
Textures - CL, SICL, GR-CL, CB-CL
Coarse fragment content - 0 to 25 percent
Clay content - 28 to 38 percent
Reaction - moderately acid through neutral
Present in some pedons:
3Btb horizon
Textures - GRX-CL, GRV-CL
Clay content - 30 to 38 percent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Culdesac soils are on hills on high basalt plateaus. Elevations are 4,100 to 5,000 feet. Slopes are 10 to 20 percent. The soils formed in a mantle of volcanic ash over loess and material weathered from basalt. The average annual precipitation is 26 to 28 inches. The frost free period is 60 to 85 days. The average annual temperature is 41 to 43 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Webbridge, Cramont, and Seddow soils. Webbridge soils are on steep canyon slopes and are loamy-skeletal below the ash mantle. Cramont soils are on hill summits, do not have a thick ash mantle, and have a clayey argillic horizon. Seddow soils are on south- and west-facing slopes, do not have a thick ash mantle, and are deep to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff under natural vegetation, medium to rapid runoff when disturbed; moderately slow permeability.
USE AND VEGETATION: Used mainly for woodland, woodland grazing, recreation and wildlife habitat. The natural vegetation is mainly grand fir, Douglas-fir, western larch, common snowberry, longtube twinflower, goldthread, and western rattlesnake plantain.
DISTRIBUTION AND EXTENT: North central Idaho. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Nez Perce County, Idaho, 1972.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from the surface to 20 inches (O, Bw, and A horizons).
Andic materials - from 2 to 20 inches (the A, Bw1, and Bw2 horizons).
Argillic horizon - from 20 to 60 inches (the 2Btb horizons).
Particle-size control section - the zone from 2 to 42 inches (the A, Bw1, Bw2, 2Btb1, and most of the 2Btb2 horizons).
ADDITIONAL DATA: A different pedon of this series has been sampled by NSSL. Laboratory sample number 91P1093; soil survey sample number S91ID-069-035.