LOCATION LOSTHORSE MT
Established Series
Rev. RJS/EMR/RJS
07/2013
LOSTHORSE SERIES
The Losthorse series consists of very deep, excessively drained soils formed in till, outwash, or colluvium derived from granite or gneiss. These soils are on moraines, outwash fans, and escarpments. Slopes are 4 to 35 percent. Mean annual precipitation is about 432 millimeters and mean annual temperature is about 6 degrees C.
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Typic Haplustepts
TYPICAL PEDON: Losthorse stony sandy loam, in forest on an 8 percent slope at 1,179 meters elevation (colors are for dry soil unless otherwise indicated.)
Oi--0 to 3 cm; slightly decomposed forest litter. (1 to 5 cm thick)
A--3 to 10 cm; grayish brown (10YR 5/2) stony sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium granular structure; soft, very friable, nonsticky and nonplastic; few very fine, fine, medium and coarse roots; many fine and medium irregular pores; 5 percent gravel, 5 percent cobbles, 10 percent stones, 5 percent boulders; moderately acid (pH 6.0); clear smooth boundary. (3 to 10 cm thick)
E--10 to 20 cm; light gray (10YR 7/2) stony sandy loam, dark grayish brown (10YR 4/2) moist; weak medium granular structure; soft, very friable, nonsticky and nonplastic; few very fine, fine, medium, and coarse roots; many fine and medium irregular pores; 5 percent gravel, 5 percent cobbles, 10 percent stones, 5 percent boulders; moderately acid (pH 6.0); clear smooth boundary. (3 to 15 cm thick)
Bw--20 to 36 cm; pale brown (10YR 6/3) bouldery coarse sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine, fine, medium, and coarse roots; many fine and medium irregular pores; 5 percent gravel, 10 percent cobbles, 5 percent stones, 5 percent boulders; moderately acid (pH 5.8); gradual smooth boundary. (15 to 32 cm thick)
C1--36 to 46 cm; very pale brown (10YR 7/3) very stony loamy coarse sand, brown (10YR 5/3) moist; single grain; loose, nonsticky and nonplastic; very few very fine, fine, medium, and coarse roots; many fine interstitial pores; 15 percent gravel, 15 percent cobbles, 10 percent stones, 2 percent boulders; moderately acid (pH 5.8); gradual smooth boundary. (10 to 30 cm thick)
C2--46 to 152 cm; pale yellow (2.5Y 7/3) very stony coarse sand, light olive brown (2.5Y 5/3) moist; single grain; loose, nonsticky and nonplastic; very few very fine, fine, and coarse roots; many fine interstitial pores; 25 percent gravel, 10 percent cobbles, 10 percent stones; moderately acid (pH 5.6).
TYPE LOCATION: Ravalli County, Montana; 700 meters south and 145 meters west of the NE corner of section 9, T7N, R21W; USGS Victor, Montana topographic quadrangle; UTM Zone 11: 713725e, 5139929n NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 8 degrees C
Depth to cambic horizon - 7 to 30 cm
Depth to sandy-skeletal material - 22 to 50 cm
Surface stones and boulders - .01 to 20 percent
A horizon:
Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: sandy loam, coarse sandy loam, or loam
Clay content: 5 to 16 percent
Rock fragments: 25 to 60 percent; 15 to 25 percent gravel, 5 to 15 percent cobbles, 10 to 25 percent stones, 0 to 10 percent boulders
Reaction: pH 5.2 to 6.0
E horizon:
Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2 to 4
Texture: sandy loam or loam
Clay content: 5 to 16 percent
Rock fragments: 25 to 60 percent; 5 to 25 percent gravel, 5 to 15 percent cobbles, 10 to 25 percent stones, 0 to 10 percent boulders
Reaction: pH 5.2 to 6.0
Bw horizon:
Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4 to 6 moist
Chroma: 2 to 4
Texture: sandy loam or coarse sandy loam
Clay content: 5 to 15 percent
Rock fragments: 25 to 60 percent; 5 to 25 percent gravel, 5 to 25 percent cobbles, 5 to 25 percent stones, 0 to 10 percent boulders
Reaction: pH 5.2 to 6.0
C horizons:
Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 to 4
Texture: loamy sand, loamy coarse sand, or coarse sand
Clay content: 0 to 5 percent
Rock fragments: 35 to 70 percent; 15 to 45 percent gravel, 5 to 25 percent cobbles, 0 to 25 percent stones, 0 to 10 percent boulders
Reaction: pH 5.2 to 6.0
COMPETING SERIES:
Chereete (MT) - do not have an E horizon; are moderately acid to neutral
Kallis (MT) - do not have an E horizon; are moderately acid to neutral
Totelake (MT) - do not have an E horizon; are neutral to slightly alkaline
GEOGRAPHIC SETTING:
Landform - moraines, outwash fans, and escarpments
Elevation - 990 to 2,060 meters
Slope - 4 to 35 percent
Parent material - till, outwash, or colluvium derived from granite or gneiss
Climate - Long, cold winters; moist springs; warm summers
Mean annual precipitation - 330 to 508 mm
Mean annual air temperature - 4 to 7 degrees C
Frost-free period - 70 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Excessively drained; moderately rapid permeability to a depth of 36 cm, rapid and very rapid below.
USE AND VEGETATION: Losthorse soils are used mainly for woodland. Vegetation is Douglas fir and ponderosa pine with an understory of snowberry, pinegrass, elk sedge, and kinnikinnick.
DISTRIBUTION AND EXTENT: Losthorse soils are of small extent in the intermountain valleys of western Montana. MLRAs 43B and 44A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Bitterroot Valley Area, Montana, 2013; proposed in Ravalli County, Montana, 2003.
REMARKS: Diagnostic features and horizons recognized in this pedon are: Ochric epipedon from the surface to 20 cm (Oi, A, and E horizons)
Cambic horizon from 20 to 36 cm (Bw horizon)
Particle-size control section from 28 to 103 cm (part of the Bw, C1 and part of the C2 horizons)
Losthorse soils have a frigid temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.