LOCATION RASTUS OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Palexerollic Durixerolls
TYPICAL PEDON: Rastus very gravelly loam - on a 2 percent slope, rangeland. (Colors are for moist soil unless otherwise noted.)
A1--0 to 4 inches; very dark grayish brown (10YR 3/2) very gravelly loam, grayish brown (10YR 5/2) dry; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine continuous tubular pores; 40 percent gravel; neutral (pH 6.8); clear smooth boundary. (3 to 5 inches thick)
A2--4 to 12 inches; very dark grayish brown (10YR 3/2) gravelly clay loam, grayish brown (10YR 5/2) dry; moderate fine granular structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and fine continuous tubular pores; 20 percent gravel; neutral (pH 7.0); abrupt smooth boundary. (0 to 10 inches thick)
2Bt--12 to 19 inches; dark yellowish brown (10YR 4/4) clay, dark yellowish brown (10YR 4/4) dry; strong very coarse angular blocky structure; very hard, very firm, very sticky and very plastic; few very fine and fine roots; few very fine and fine continuous tubular pores; many prominent clay films on faces of peds and in pores; 10 percent gravel, neutral (pH 7.2); clear smooth boundary. (6 to 8 inches thick)
2Btk--19 to 24 inches; dark yellowish brown (10YR 4/4) gravelly clay, dark yellowish brown (10YR 4/6) dry; strong medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine roots; few fine discontinuous tubular pores; many prominent clay films on face of peds and in pores; 25 percent gravel; strongly effervescent; slightly alkaline (pH 7.8); abrupt wavy boundary. (0 to 7 inches thick)
2Bkqm--24 to 37 inches; brownish yellow (10YR 6/6) and very pale brown (10YR 8/3) dry; indurated duripan; violently effervescent; strongly alkaline (pH 8.6); abrupt wavy boundary. (10 to 20 inches thick)
3C--37 to 60 inches; multicolored extremely gravelly sandy loam; massive; 70 percent gravel; slightly alkaline (pH 7.6).
TYPE LOCATION: Baker County, Oregon; located 1,700 feet north and 2,000 feet east of the SW corner of section 27, in the NE1/4 SW1/4 sec. 27, T. 13 S., R. 37 E.
RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in all parts between 4 and 12 inches for 45 to 80 consecutive days following the summer solstice. The mean annual soil temperature is 43 to 47 degrees F. Depth to the duripan is 20 to 30 inches. Depth to the 2Bt is 10 to 15 inches. Depth to bedrock is over 60 inches. There is an absolute increase in clay content of 15 to 30 percent between the A2 and 2Bt horizons. Rock fragments are typically rounded.
The A horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 2 or 3 moist and dry. It has 35 to 50 percent gravel and 0 to 10 percent cobbles.
The 2Bt horizon has value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist, 4 or 5 dry. It has 50 to 60 percent clay. It has 0 to 30 percent gravel. It is neutral or slightly alkaline.
The 2Btk, when present, has value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist and 4 through 6 dry. It has 50 to 60 percent clay. It has 10 to 30 percent gravel.
The Bkqm horizon is indurated throughout or indurated in the upper few inches and strongly cemented below. It is strongly or violently effervescent.
The 3C horizon is sandy loam or loamy sand with 35 to 60 percent gravel and 10 to 20 percent cobbles. It is neutral or slightly alkaline.
COMPETING SERIES: These are the Cadlebutte and Pankeybasin series. Cadlebutte soils have bedrock at 25 to 40 inches. Pankeybasin soils are on bedrock controlled plateaus, and lack the sand and gravel material below the duripan.
GEOGRAPHIC SETTING: The Rastus soils are on high terraces. Slopes are 1 to 10 percent. Elevations range from 4,000 to 5,400 feet. These soils formed in mixed alluvium. The mean annual precipitation is 12 to 18 inches. The mean annual temperature is 40 to 45 degrees F. The frost-free period is 30 to 90 days. This soil is on the Eola geomorphic surface.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Campcreek, Marack, Skullgulch, and Wahstal soils. Campcreek and Skullgulch soils are mapped in association on adjacent side slopes. Campcreek soils have mollic epipedons less than 20 inches thick and are located on south-facing slopes. Skullgulch soils have mollic epipedons greater than 20 inches thick and are located on north-facing slopes. Marack soils are on adjacent lower terraces, and have a calcic horizon. Wahstal soils are clayey-skeletal and shallow to a duripan.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is slow. Permeability is slow.
USE AND VEGETATION: These soils are used for rangeland. The native vegetation in MLRA 10 is bluebunch wheatgrass, Idaho fescue, mountain big sagebrush, and gray rabbitbrush. The native vegetation in MLRA 9 is Idaho fescue, bluebunch wheatgrass and Sandberg bluegrass.
DISTRIBUTION AND EXTENT: Eastern Oregon. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Baker County Area, Oregon; 1988.
REMARKS: Diagnostic horizons and features in this pedon are:
Mollic epipedon - the zone from the surface of the soil to a depth of 12 inches (A1, A2 horizons).
Argillic horizon - the zone from 12 to 24 inches (2Bt, 2Btk horizons).
(Abruptic) feature - there is an absolute increase in the clay content of 15 to 30 percent between the A2 and 2Bt horizons.
Duripan: The zone from 24 to 37 inches; it is indurated throughout.