LOCATION MOBATE WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid, shallow Vitrandic Haploxerepts
TYPICAL PEDON: Mobate gravelly ashy loam, woodland. (Colors are for dry soil unless otherwise stated.)
0i--0 to 1 inch; needles, leaves, twigs, bark and cones; smooth boundary. (1/2 to 3 inches thick)
A--1 to 4 inches; grayish brown (10YR 5/2) gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium granular structure; slightly hard, friable, slightly sticky and nonplastic; many fine and medium roots; many fine pores; 20 percent gravel by volume; slightly acid (pH 6.4).
Bw--4 to 11 inches; pale brown (10YR 6/3) gravelly ashy loam, brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few fine, medium and coarse roots; common fine pores; 25 percent gravel; slightly acid (pH 6.4); clear wavy boundary. (5 to 8 inches thick)
BC--11 to 17 inches; very pale brown (10YR 7/3) very gravelly sandy loam, brown (10YR 5/3) moist; massive; slightly hard, friable, slightly sticky and nonplastic; few fine roots; few fine pores; 40 percent gravel; slightly acid (pH 6.4); clear wavy boundary. (4 to 8 inches thick)
Cr--17 inches; slightly weathered granite.
TYPE LOCATION: Stevens County, Washington; 1,600 feet west and 100 feet north of the SE corner section 4, T.29N., R.21E., W.M.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 14 to 20 inches. The soils are usually moist but they are dry in all parts between a depth of 8 inches and the paralithic contact for 60 to 80 days following the summer solstice. The mean annual soil temperature is about 45 to 47 degrees F. The soil is slightly acid or neutral.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3. It has 5 to 25 percent gravel.
The Bw horizon have value of 5 or 6 dry, 3 or 4 moist, and chroma of 3 or 4. It is gravelly ashy loam or gravelly ashy sandy loam and has 15 to 30 percent gravel.
The BC horizon has value of 5 through 7 dry, 4 or 5 moist, and chroma of 3 or 4. It is very gravelly loam or very gravelly sandy loam and has 35 to 55 percent gravel. Some pedons have a C horizon.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Mobate soils are on granitic uplands at elevations of 2,500 to 4,500 feet. Slopes are 0 to 65 percent. The soils formed in residuum from granite with a component of loess and volcanic ash in the surface layer. The climate is characterized by warm dry summers and cool moist winters. The mean annual precipitation is 20 to 28 inches. The average January temperature is about 28 degrees F.; the average July temperature is about 60 degrees F.; and the mean annual temperature is 43 to 45 degrees F. The frost free season is about 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Moscow, Skanid and Spokane soils. Moscow and Spokane soils are 20 to 40 inches deep to a paralithic contact. Spokane and Skanid soils are mesic.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; moderate permeability.
USE AND VEGETATION: Used mainly for woodland. Vegetation is Douglas fir, ponderosa pine, few western larch, and grand fir. With an understory of redstem ceanothus, Oregon grape, wild rose, kinnikinnick, bluebunch wheatgraas, pinegrass and strawberry.
DISTRIBUTION AND EXTENT: Northeastern Washington granitic areas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Stevens County, Washington, 1978.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the mineral surface to 4 inches, a cambic horizon from 4 to 17 inches, and a paralithic contact at 17 inches. The upper 11 inches of this pedon is estimated to have volcanic glass content of 5 to 20 percent and acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 0.4 to 1.0 percent. This descriptions reflects a change in classification from Loamy-skeletal, mixed, frigid, shallow Vitrandic Xerochrepts to Loamy-skeletal, isotic, frigid, shallow Vitrandic Haploxerepts.