LOCATION MONAD MT+CO
Established Series
Rev. HAL-GFB-RJS
05/2011
MONAD SERIES
The Monad series consists of very deep, well drained soils that formed in slope alluvium, colluvium and outwash derived mainly from argillite, sandstone and quartzite. These soils occur on alluvial fans, hills, ground moraines and mountains. Slopes are 2 to 60 percent. Mean annual precipitation is about 21 inches, and mean annual air temperature is about 39 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Alfic Argicryolls
TYPICAL PEDON: Monad gravelly loam, in rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 9 inches; very dark gray (10YR 3/1) gravelly loam, black (10YR 2/1) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, and few medium roots; 15 percent gravel and cobbles; slightly acid (pH 6.2); clear wavy boundary. (6 to 11 inches thick)
A2--9 to 14 inches; grayish brown (10YR 5/2) channery loam, very dark grayish brown (10YR 3/2) moist; moderate very fine and fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine and fine, and few medium roots; many very fine and fine, and few medium pores; very thin continuous gray (10YR 6/1) skeletans coating faces of peds; 15 percent channers; moderately acid (pH 5.8); gradual wavy boundary. (0 to 8 inches thick)
Bt/E--14 to 21 inches; Bt part (80 percent) brown (10YR 5/3) loam, brown (10YR 4/3) moist; E part (20 percent) gray (10YR 6/1) loam, dark gray (10YR 4/1) moist; weak medium prismatic structure parting to moderate fine subangular blocky; very hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; many very fine and fine, and few medium pores; very thin continuous gray (10YR 6/1) skeletans coating continuous faint clay films on faces of peds; 10 percent sandstone channers; moderately acid (pH 5.7); clear wavy boundary. (5 to 17 inches thick)
Bt1--21 to 49 inches; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; weak medium prismatic structure parting to moderate fine and medium blocky; extremely hard, firm, very sticky and moderately plastic; few very fine and fine roots; many very fine and fine, and few medium pores; very thin gray (10YR 6/1) skeletans coating continuous distinct clay films on faces of peds; 10 percent sandstone channers; moderately acid (pH 5.8); gradual wavy boundary. (9 to 28 inches thick)
Bt2--49 to 74 inches; very pale brown (10YR 7/4) stony clay loam, brown (7.5YR 5/4) moist; strong fine and medium blocky structure; extremely hard, firm, very sticky and moderately plastic; many very fine and fine, and few medium pores; continuous distinct clay films on faces of peds; 15 percent cobbles and 10 percent stones; slightly alkaline (pH 7.4).
TYPE LOCATION: Cascade County, Montana; 700 feet east and 1,340 feet south of the NW corner of the NE 1/4 of sec. 27, T. 17N, R. 5E.
RANGE IN CHARACTERISTICS:
Soil temperature - 35 to 41 degrees F.
Mollic epipedon thickness - 10 to 16 inches
Depth to glossic horizon - 10 to 16 inches
Depth to top of argillic horizon - 10 to 16 inches
Note: Some pedons may have an E/Bt horizon.
A1, A2 horizons
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 1 or 2; dry or moist
Texture: loam or fine sandy loam
Clay content: 10 to 27 percent
Rock fragments: 0 to 35 percent--0 to 25 percent gravel, 0 to 10 percent cobbles
Reaction: pH 5.6 to 7.3
Bt/E horizon
Value: Bt part - 4 to 6 dry; 4 or 5 moist; E part - 6 or 7 dry; 4 or 5 moist
Chroma: Bt part - 2 to 4; dry or moist; E part - 1 to 3; dry or moist
Texture: loam, clay loam or sandy clay loam
Clay content: 22 to 35 percent
Rock fragments: 10 to 35 percent--10 to 30 percent gravel or channers, 0 to 5 percent cobbles and stones
Reaction: pH 5.6 to 7.3
Bt1, Bt2 horizons
Hue: 10YR or 7.5YR; dry or moist
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 3 to 6; dry or moist
Texture: clay loam, loam or sandy clay loam
Clay content: 22 to 35 percent
Rock fragments: 10 to 35 percent--0 to 25 percent gravel or channers, 0 to 15 percent cobbles, 0 to 15 percent stones
Reaction: pH 5.6 to 7.8
COMPETING SERIES:
Anvik (CO) - does not have a glossic horizon
Bear Basin (UT) - have greater than 35 percent rock fragments below the argillic horizon
Buffork (WY) - are moderately deep to a paralithic contact
Slipman (WY) - are deep to a lithic contact
GEOGRAPHIC SETTING:
Landform - alluvial fans, hills, ground moraines and mountains
Elevation - 4,600 to 8,100 feet
Slope - 2 to 60 percent
Parent material - slope alluvium, colluvium and outwash derived mainly from argillite, sandstone and quartzite
Mean annual precipitation - 14 to 24 inches
Mean annual air temperature - 34 to 39 degrees F.
Frost-free period - 30 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Libeg,
Loggert, and
Tigeron soils. These soils contain more than 35 percent rock fragments in the particle-size control section. Loggert and Tigeron soils lack a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Monad soils are used mainly for rangeland. Potential native vegetation is mainly rough fescue, Idaho fescue, Richardson needlegrass, mountain brome, forbs and shrubs.
DISTRIBUTION AND EXTENT: Monad soils are of moderate extent in west-central Montana and Colorado. MLRAs - 43B, 46, 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Cascade County, Montana, 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 14 inches (A1, A2 horizons
Glossic horizon - from 14 to 21 inches (Bt/E horizon)
Argillic horizon - from 14 to 74 inches (Bt/E, Bt1, Bt2 horizons)
Particle-size control section - from 14 to 34 inches (Bt/E, part of Bt1 horizons)
Monad soils have a cryic temperature regime and an ustic moisture regime.
ADDITIONAL DATA: Soil interpretations record - MT0115.
National Cooperative Soil Survey
U.S.A.