LOCATION SLIDEMOUNTAIN MT
Established Series
REV. JJU-RJS
01/2012
SLIDEMOUNTAIN SERIES
The Slidemountain series consists of shallow, well drained soils that formed in colluvium over residuum derived from igneous rock. These soils occur on mountain slopes and ridges. Slopes are 4 to 45 percent. Mean annual precipitation is about 660 mm, and the mean annual air temperature is about 3 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Lithic Argicryolls
TYPICAL PEDON: Slidemountain gravelly loam, in forest on a 12 percent slope at an elevation of 2615 meters (Colors are for dry soil unless otherwise noted).
Oi--0 to 6 cm; slightly decomposed forest litter; clear smooth boundary. (2 to 10 cm thick)
A--6 to 22 cm; very dark grayish brown (10YR 3/2) gravelly loam, very dark brown (10YR 2/2) moist; moderate medium granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, fine, and medium roots; many very fine and fine irregular pores; 20 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (14 to 25 cm thick)
Bt1--22 to 36 cm; dark grayish brown (10YR 4/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine irregular pores; 20 percent faint clay films on faces of peds; 35 percent gravel; slightly acid (pH 6.2); clear wavy boundary.
Bt2--36 to 45 cm; brown (10YR 4/3) very gravelly clay loam, dark grayish brown (10YR 4/2) moist; strong coarse subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; common fine tubular pores; 50 percent distinct clay films on faces of peds; 45 percent gravel and 5 percent cobbles; slightly acid (pH 6.2); abrupt smooth boundary. (combined thickness of Bt horizons is 15 to 25 cm)
R--45 to 152 cm; indurated basalt bedrock.
TYPE LOCATION: Beaverhead County, Montana; located about 64 meters south and 128 meters east of the northwest corner of sec. 31, T. 14 N., R 2 W; Winslow Creek topographic quadrangle; UTM 12T, 428400e., 4936343n. NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 2 to 5 degrees C.
Thickness of mollic epipedon - 18 to 36 cm
Depth to top of argillic horizon - 14 to 25 cm
Depth to lithic contact - 25 to 50 cm
Particle-size control section - averages 18 to 35 percent clay
A horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Clay content: 18 to 27 percent
Rock fragments: 15 to 35 percent gravel
Reaction: pH 5.6 to 6.4
Bt horizons
Value: 4 to 6 dry; 3 or 4 moist
Chroma: 2 or 3; dry or moist
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 35 to 60 percent--35 to 55 percent gravel, 0 to 15 percent cobbles
Reaction: pH 5.6 to 6.4
COMPETING SERIES:
Bushpark (CO) - the wettest months are in July and August
Copenhaver (MT) - has an ustic moisture regime
Donkehill (ID) - has a xeric soil moisture regime
Hogmalat (ID) - has a xeric soil moisture regime
Layview (NV) - has a xeric soil moisture regime
Maygal (NV) - has a xeric soil moisture regime
Mosroc (WY) - has an ustic moisture regime
Mountpatterson (CA) - has a xeric soil moisture regime
Nielsen (ID) - has a xeric soil moisture regime
Nieman (MT) - has an ustic soil moisture regime
Notstew (NV) - has a xeric soil moisture regime
Thiefridge (CA) - has a xeric soil moisture regime
GEOGRAPHIC SETTING:
Landform - mountain slopes and ridges
Elevation - 2190 to 2750 meters
Slope - 4 to 45 percent
Parent material - colluvium over residuum derived from igneous rock
Climate - long, cold winters; moist springs; short warm summers
Mean annual precipitation - 600 to 1025 mm
Mean annual air temperature - 1 to 4 degrees C.
Frost-free period - 30 to 50 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Slidemountain soils are used mainly for timber and understory grazing. The vegetation is mainly subalpine fir, Douglas-fir, snowberry, buffaloberry, heartleaf arnica, pinegrass, and other miscellaneous grasses and forbs.
DISTRIBUTION AND EXTENT: Slidemountain 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, 2010.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 6 to 36 cm (A and Bt1 horizons)
Argillic horizon - from 22 to 45 cm (Bt1 and Bt2 horizons)
Particle-size control section - from 22 to 45 cm (Bt1 and Bt2 horizons)
Slidemountain soils have a cryic temperature regime and an udic moisture regime.
Taxonomic version: Eleventh Edition, 2010.
National Cooperative Soil Survey
U.S.A.