LOCATION MOSBY MTInactive Series
TAXONOMIC CLASS: Fine, smectitic, calcareous, frigid Aridic Ustorthents
TYPICAL PEDON: Mosby silty clay loam, grassland, 4 percent slopes. (Colors are for dry soil unless otherwise stated.)
A1--0 to 3 inches; light yellowish brown (2.5Y 6/3) silty clay loam, olive brown (2.5Y 4/3) moist; moderate fine granular structure: hard, very friable, sticky and plastic; strong effervescence; clear boundary. (1 to 4 inches thick)
B2--3 to 25 inches; pale yellow (5Y 7/3) heavy silty clay loam, pale olive and olive (5Y 6/3 and 5/3) moist; weak medium and coarse prismatic structure; very hard, friable, sticky and plastic; strong effervescence; a few shale chips in lower part; clear boundary. (18 to 28 inches thick)
C1--25 to 28 inches; pale yellow (5Y 7/3) heavy silty clay loam, olive (5Y 6/3) moist; weak platy structure; hard, friable, sticky and plastic; numerous soft shale fragments; strong effervescence. (3 to 6 inches thick)
C2--28 to 42+ inches; olive colored platy heavy silty clay loam or light silty clay mudstones; strong effervescence.
TYPE LOCATION: Garfield County, Montana, Section 13, T16N, R40E, about 750 feet east of NW corner of Section in road cut on south side of road.
RANGE IN CHARACTERISTICS: Depth to paralithic contact is usually less than 32 inches, but ranges from 20 to 40 inches. The control section is heavy clay loam, heavy silty clay loam, light clay, or light silty clay with 36 to 45 percent clay, 45 to 60 percent silt plus very fine sand, and 0 to 15 percent fine and coarser sand. Mineralogy is mixed with only small amounts of montmorillonitic type clays. The epipedon has colors in hues of 5Y or 2.5Y with values of 5 or 6 dry and 4 moist and chroma of 2 or 3. The B2 (cambic) horizons have weak to moderate grades of prismatic with or without blocky structure; have strong or very strong effervescence; and have colors in hues of 2.5Y or 5Y with values of 6 or 7 dry and 4 or 5 moist, with chroma of 2 to 4. The B2 horizon may have a few masses or threads of segregated lime below 12 inches. The C horizons may have some masses of segregated lime. The paralithic contact consists of platy or massive siltstone, mudstone, shale or claystone. The estimated CaC03 equivalent of the control section is about 10 to 15 percent.
COMPETING SERIES: These include the Abor, Bainville, Cabbar, Cohagen, Das, Delphill, Dilts, Goodale, Kobar, Lisam, Lothair, Megland, Megon, Razor, Remuda, Scroggin, and Yawdim series. The Abor soils have more than 45 percent clay in their control section. The Bainville, Cohagen, Das, Delphill, Remuda and Scroggin soils have less than 35 percent clay in their control sections. The Cabbar, Dilts, Lisam, and Yawdim soils have the paralithic control between 10 and 20 inches. The Goodale and Kobar soils have no paralithic contact within 60 inches. The Lothair soils have no diagnostic subsurface horizon and have no paralithic contact. The Megland soils are usually moist in the moisture control section. The Megon soils have more strongly expressed B2 horizons with a horizon of segregated lime and have a lower CaC03 equivalent percent. The Razor soils have mean annual soil temperature warmer than 47 degrees F. (8 degrees C.).
GEOGRAPHIC SETTING: The Mosby soils are on the mid and lower slopes in the undulating to rolling sedimentary uplands. The regolith consists of clayey residuum weathered in place from the underlying calcareous silty clay loam shales of Cretaceous or Tertiary ages. The climate is cool, semiarid, continental, with long, cold, dry winters and moist springs and summers. The mean annual precipitation is 10 to 14 inches, more than 70 percent of which falls when soil temperature at 20 inches (50 cm) is about 41 degrees F. (5 degrees F.) The mean annual temperature is 42 to 45 degrees F., mean January temperature about 18 to 25 degrees F. and mean July temperature 66 to 72 degrees F. The frost-free period is 105 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Cabbar, Galhand, Goodale, Kobar, Lothair, and Yawdim series. The Galhand soils have the paralithic contact at depths of 10 inches and less.
DRAINAGE AND PERMEABILITY: Well drained with slow intake and medium to rapid runoff. Permeability is slow.
USE AND VEGETATION: The Mosby soils are used for both nonirrigated cropland and rangeland. The uncultivated areas have a cover of western wheatgrass, needleandthread, blue grama, and fringed sagewort.
DISTRIBUTION AND EXTENT: The Mosby series is widely distributed in all the counties in the eastern plains of Montana and possible in adjacent states. It is an extensive series.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES PROPOSED: Garfield County, Montana, 1964. This is a place name.
REMARKS: The Mosby series was formerly classified in the Lithosol group.
OSED scanned by SSQA. Last revised by state on 12/68.