LOCATION BEECHCREEK MT
Established Series
Rev. JJU-RJS
01/2012
BEECHCREEK SERIES
The Beechcreek series consists of moderately deep, well drained soils that formed in volcanic ash influenced colluvium over residuum derived from rhyolite. These soils occur on hills and mountain slopes. Slopes are 4 to 35 percent. Mean annual precipitation is about 406 mm, and the mean annual air temperature is about 4 degrees C.
TAXONOMIC CLASS: Ashy-skeletal, glassy Vitrandic Argicryolls
TYPICAL PEDON: Beechcreek gravelly ashy sandy loam, in rangeland on a 12 percent slope at an elevation of 2103 meters (Colors are for dry soil unless otherwise noted).
A--0 to 19 cm; dark grayish brown (10YR 4/2) gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, slightly sticky and nonplastic; many very fine, fine, medium, and coarse roots; many very fine and fine irregular pores; 25 percent gravel and 5 percent cobbles; neutral (pH 7.0); clear smooth boundary. (14 to 20 cm thick)
Bt--19 to 36 cm; grayish brown (10YR 5/2) very gravelly ashy sandy clay loam, brown (10YR 4/3) moist; moderate medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine and medium roots; many very fine and fine irregular pores; 95 percent distinct clay films on faces of peds and on rock fragments; 40 percent gravel and 5 percent cobbles; neutral (pH 7.2); clear wavy boundary. (15 to 38 cm thick)
BC--36 to 61 cm; light brownish gray (10YR 6/2) very gravelly ashy sandy clay loam, grayish brown (10YR 5/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few fine roots; many fine irregular pores; 45 percent gravel; neutral (pH 6.8); clear irregular boundary. (0 to 30 cm thick)
Cr--61 to 84 cm; light gray (2.5Y 7/1) decomposing volcanic ash influenced rhyolitic bedrock. (15 to 30 cm thick)
R--84 cm; fractured volcanic ash influenced rhyolitic bedrock.
TYPE LOCATION: Beaverhead County, Montana; 500 feet east and 1,400 feet south of the northwest corner of sec. 8, T. 11 S., R. 8 W.; Beech Creek topographic quadrangle; UTM 12T, 372691e. 4972617n. NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 1 to 4 degrees C
Thickness of the mollic epipedon - 18 to 32 cm
Depth to argillic horizon - 15 to 30 cm
Depth to paralithic contact - 50 to 85 cm
Depth to lithic contact - 65 to 100 cm
Volcanic glass content - 30 to 50 percent in the .02 to 2.0 mm fraction
Note: Some pedons have a C horizon.
A horizon
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Clay content: 12 to 18 percent
Rock fragments: 15 to 35 percent--15 to 30 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.6 to 7.3
Bt horizons
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 2 to 4 dry; 2 or 3 moist
Texture: loam or sandy clay loam
Clay content: 20 to 35 percent
Rock fragments: 35 to 60 percent--35 to 55 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.6 to 7.3
BC horizon
Hue: 2.5Y or 10YR
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 to 4 dry: 2 or 3 moist
Texture: sandy loam or sandy clay loam
Clay content: 15 to 25 percent
Rock fragments: 35 to 60 percent--35 to 55 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.6 to 7.3
COMPETING SERIES:
Ashflat (CA) - are deeper than 100 cm to bedrock
Boulderfan (CA) - are deeper than 100 cm to bedrock
Cowbell (CA) - are deeper than 100 cm to bedrock
Euell (MT) - are deeper than 100 cm to bedrock
Fendersflat (CA) - have a xeric moisture regime
Hardshoulder (CA) - are deeper than 100 cm to bedrock
Paynepeak (CA) - have a xeric moisture regime
Pyropatti (CA) - have a xeric moisture regime
Snag (NV) - have a xeric moisture regime
Tusune (NV) - have a xeric moisture regime
GEOGRAPHIC SETTING:
Landform - hills and mountain slopes
Elevation - 2072 to 2286
Slope - 4 to 35 percent
Parent material - volcanic ash influenced colluvium over residuum derived from rhyolite
Climate - long, cold winters; moist springs; short warm summers
Mean annual precipitation - 381 to 483 mm
Mean annual temperature - 1 to 4 degrees C
Frost-free period - 50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Beechcreek soils are used mainly for rangeland. Potential native vegetation is mainly Idaho fescue, bluebunch wheatgrass, prairie junegrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Beechcreek soils are of small extent in southwestern Montana. MLRA 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Horse Prairie-South Valley Area - Part of Beaverhead County, Montana, 2011; proposed in Beaverhead County, Montana, 2009.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 19 cm (A horizon)
Argillic horizon - from 19 to 36 cm (Bt horizon)
Particle-size control section - from 19 to 36 cm (Bt horizon)
Beechcreek soils have a cryic temperature regime and an ustic moisture regime.
Taxonomic version: Tenth Edition, 2006
National Cooperative Soil Survey
U.S.A.