LOCATION CRASH ID+MTEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, frigid Lamellic Hapludalfs
TYPICAL PEDON: Crash silt loam, woodland; on a north-facing slope of 65 percent at 2,100 feet elevation. When described on August 23, 1972, the soil was dry throughout. The pedon was redescribed on September 26, 1994. (Colors are for dry soil unless otherwise stated.)
Oi--0 to 1 inch; needles, twigs and limbs. (1 to 2 inches thick)
Oe--1 to 2 inches; partly decomposed needles, twigs and limbs. (0.5 to 1 inch thick)
A1--2 to 3 inches; light gray (5Y 7/1) silt loam, gray (5Y 5/1) moist; moderate fine granular structure; soft, friable, nonsticky and nonplastic; many roots; many pores; slightly acid (pH 6.3); abrupt broken boundary. (0 to 1.5 inches thick)
A2--3 to 5 inches; light gray (5Y 7/1) silt loam, gray (5Y 5/1) moist; weak very thin platy structure parting to moderate very fine granular; soft, friable, slightly sticky and slightly plastic; many very fine, fine and medium roots; many very fine and few fine pores; many fine black concretions; neutral (pH 6.6); abrupt smooth boundary. (2 to 4 inches thick)
AB--5 to 9 inches; light olive gray (5Y 6/2) silt loam, olive gray (5Y 5/2) moist; moderate thin platy structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, medium and few coarse roots; common very fine and few fine pores; many fine black concretions; neutral (pH 6.7); clear wavy boundary. (3 to 6 inches thick)
Bt1--9 to 13 inches; light gray (5Y 7/2) silt loam, light olive gray (5Y 6/2) moist; weak fine and medium platy structure; slightly hard, firm, slightly sticky and slightly plastic; many very fine, fine and medium roots; common very fine and few fine pores; few faint clay films on faces of peds and lining pores; 50 to 70 percent of the horizon consists of dark yellowish brown lamellae 1/8 to 1/2 inch thick that have about 10 percent more clay than the matrix; few very fine black concretions; neutral (pH 6.8); clear wavy boundary. (3 to 7 inches thick)
Bt2--13 to 20 inches; light gray (5Y 7/2) silt loam, light brownish gray (2.5Y 6/2) moist; moderate medium and very coarse platy structure; slightly hard, firm, slightly sticky and slightly plastic; many very fine, fine and few medium roots; many very fine and few fine pores; few faint clay films on faces of peds and lining pores; 50 to 70 percent of the horizon consists of dark yellowish brown lamellae 1/8 to 1/2 inch thick that have about 10 percent more clay than the matrix; few very fine black concretions; slightly alkaline (pH 7.6); clear wavy boundary. (6 to 12 inches thick)
Bt3--20 to 29 inches; light olive gray (5Y 6/2) silt loam, grayish brown (2.5Y 5/2) moist; moderate coarse platy structure; slightly hard, firm, slightly sticky and slightly plastic; few very fine and fine roots; many very fine and fine pores; few faint clay films on faces of peds and lining pores; 5 to 20 percent of this horizon has dark yellowish brown lamellae 1/8 to 1/4 inch thick that have about 10 percent more clay than the matrix; few very fine black concretions; slightly alkaline (pH 7.8); gradual wavy boundary. (8 to 12 inches thick)
Bk--29 to 60 inches; light olive gray (5Y 6/2) silt loam, grayish brown (2.5Y 5/2) moist; moderate coarse platy structure; very hard, very firm, slightly sticky and slightly plastic; violently effervescent (calcium carbonate); distinct lime veins and masses between plates; moderately alkaline (pH 8.0).
TYPE LOCATION: Boundary County, Idaho; about 2 miles south of the Bonners Ferry Forest Ranger Station east of U. S. Highway 95; about 100 feet north and 1,580 feet east of the SW corner of sec. 9, T. 61 N., R. 1 E.; Latitude - 48 degrees, 38 minutes, 43 seconds North; Longitude - 116 degrees, 21 minutes, 00 seconds West; USGS Bonners Ferry Quadrangle.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 42 to 45 degrees F.
Average summer soil temperature - 49 to 52 degrees F. with an O horizon
Recent volcanic ash - very thin light gray layer occurs beneath the O horizons in undisturbed areas
Clay content - 8 to 18 percent in the particle-size control section
A horizons
Hue - 5Y, 2.5Y, or 10YR
Value - 5 to 7 dry, 3 to 5 moist
Chroma - 1 or 2 dry or moist
Texture - SIL, SI
Clay content - 0 to 10 percent
Reaction - slightly acid to neutral
AB horizon
Hue - 5Y, 2.5Y or 10YR
Value - 6 or 7 dry, 5 or 6 moist
Texture - SIL, SI
Clay content - 0 to 10 percent
Reaction - slightly acid to neutral
Bt horizons
Hue - 5Y or 2.5Y
Value - 6 or 7 dry, 5 or 6 moist
Chroma - 2 or 3 dry or moist
Texture - SIL, SI
Clay content - 8 to 18 percent
Lamellae - 1/8 to 2 inches thick
Reaction - neutral to slightly alkaline
Bk horizon
Value - 6 or 7 dry, 5 or 6 moist
Chroma - 2 or 3 dry or moist
Texture - SIL, SI
Clay content - 2 to 12 percent
Calcium carbonate - strongly effervescent or violently effervescent, distinct or prominent lime veins and masses
Calcium carbonate equivalen - 10 to 25 percent
COMPETING SERIES: This is the Artnoc series. Artnoc soils do not have a Bk horizon.
GEOGRAPHIC SETTING: Crash soils are on north-facing terrace escarpments. Slopes range from 35 to 75 percent. They formed in silty calcareous glaciolacustrine sediments. Elevations range from 1,800 to 2,700 feet. The climate is humid with cold, wet winters and warm, relatively dry summers. The average annual air temperature ranges from 42 to 44 degrees F. and the average annual precipitation is 25 to 30 inches. The average frost-free period is 80 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Artnoc, Caboose and Wishbone soils. Artnoc soils are on west and east-facing terrace escarpments and do not have a Bk horizon. Caboose soils are on southeast and southwest facing terrace escarpments and have a xeric moisture regime. Wishbone soils are on south facing terrace escarpments and have a mesic temperature regime.
DRAINAGE AND PERMEABILITY: Well drained; rapid to very rapid runoff; moderately slow permeability.
USE AND VEGETATION: Woodland, wildlife habitat, and recreation. Natural vegetation is mainly western hemlock, western redcedar, western white pine, western larch, Douglas-fir, ponderosa pine, and lodgepole pine, with and understory of myrtle pachystima, baldhip rose, longtube twinflower, queencup beadlily, darkwoods violet, and western rattlesnake plantain.
DISTRIBUTION AND EXTENT: Northern Idaho, northwestern Montana, and possibly northeastern Washington. Series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Boundary County, Idaho, 1974.
REMARKS: Classifiaction change from Psammentic Haploxeralfs coarse-silty, mixed, frigid to Psammentic Glossoboralfs coarse-silty, mixed in 1994. Natural vegetation indicates udic moisture regime. Classification changed to Coarse-silty, mixed, superactive, frigid Lamellic Hapludalfs in 1998 due to eighth edition of Soil Taxonomy.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 2 to 9 inches (A1, A2, and AB horizons)
Argillic horizon - the zone from 9 to 29 inches (Bt1, Bt2, and Bt3 horizons)
Particle-size control section - the zone from 9 to 29 inches (Bt1, Bt2, and Bt3 horizons)