LOCATION SIMAS OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Palexerolls
TYPICAL PEDON: Simas very stony clay loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; grayish brown (10YR 5/2) very stony clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium platy structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine pores; 15 percent gravel, 10 percent cobbles, 10 percent stones; slightly alkaline (pH 7.8); abrupt smooth boundary. (4 to 12 inches thick)
2Bt--5 to 14 inches; brown (10YR 5/3) clay, dark brown (10YR 3/3) moist; moderate fine and medium prismatic structure parting to strong medium blocky; extremely hard, very firm, very sticky and very plastic; many very fine roots; few very fine pores; continuous faint clay films or pressure faces; about 2 percent gravel; moderately alkaline (pH 8.3); clear wavy boundary. (5 to 17 inches thick)
2Btk--14 to 21 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 3/4) moist; weak medium prismatic structure parting to strong medium blocky; extremely hard, very firm, very sticky and very plastic; common very fine roots; few very fine pores; continuous faint clay films or pressure faces; about 2 percent cobbles; strongly effervescent and common white lime spots; moderately alkaline (pH 8.4); clear wavy boundary. (3 to 9 inches thick)
2Bk1--21 to 27 inches; yellowish brown (10YR 5/4) gravelly clay, dark yellowish brown (10YR 3/4) moist; moderate medium subangular blocky structure; very hard, firm, moderately sticky and very plastic; few very fine roots; many very fine pores; 20 percent gravel, 5 percent cobbles; many white lime spots; strongly effervescent throughout; strongly alkaline (pH 8.5); clear wavy boundary. (4 to 18 inches thick)
2Bk2--27 to 60 inches; light yellowish brown (10YR 6/4) very cobbly clay loam, dark yellowish brown (10YR 4/4) moist; massive; very hard, firm, moderately sticky and very plastic; many very fine pores; 20 percent gravel, 15 percent cobbles, 5 percent stones; many white lime seams up to 1/4 inch wide; strongly effervescent; strongly alkaline (pH 8.5).
TYPE LOCATION: Grant County, Oregon; about 15 miles west of Mt. Vernon, Oregon; 1/3 mile up Marks Creek road from its junction with Hwy. 26; above road, 50 yards above the first sharp turn; SW1/4SW1/4 sec. 7, T. 13 S., R. 28 E. Latitude - 44 degrees, 27 minutes, 03 seconds North; Longitude - 119 degrees, 24 minutes, 18 seconds West. UTM 11 0308543 4924870
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 54 degrees F. The soils are dry in all parts between depths of 4 and 12 inches for at least half the time (cumulative) during the period the soil temperature is above 41 degrees F, and dry between depths of 4 and 12 inches for more than 80 consecutive days during the summer; aridic soil moisture regime. Depth to a paralithic contact is 60 or more inches. Total rock fragments range from 0 to 35 percent in the particle-size control section. The mollic epipedon is 10 to 20 inches thick. Depth to soft powdery secondary lime is 10 to 30 inches.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 or 2. It is loam, clay loam, silt loam, or silty clay loam, with 20 to 40 percent clay, 0 to 20 percent stones, 0 to 30 percent cobbles and 0 to 20 percent gravel. It is neutral or slightly alkaline.
The 2Bt horizon has value of 3 through 6 dry, 2 to 4 moist and chroma of 2 to 4 moist and dry. The 2Btk horizon has value of 3 or 4 moist, 4 through 6 dry and chroma of 3 or 4 moist and dry. It is clay, gravelly clay or cobbly clay. It has 50 to 60 percent clay, 0 to 30 percent cobbles and 0 to 25 percent gravel. It is slightly or moderately alkaline. The 2Btk horizon is slightly to strongly effervescent.
The 2Bk horizon has value of 3 to 5 moist, 5 to 7 dry and chroma of 3 or 4 moist and dry. It is clay loam or clay with 35 to 50 percent clay, 15 to 50 percent rock fragments, dominantly gravel and cobbles. It is moderately or strongly alkaline.
COMPETING SERIES: These are the Pung and Shadoval series. Pung soils have weak silica cementation below the argillic horizon. Shadoval soils are moderately deep to a paralithic contact.
GEOGRAPHIC SETTING: Simas soils are on hills at elevations of 1,200 to 4,000 feet. At higher elevations, they are only on south-facing slopes. Slopes range from 0 to 80 percent. These soils formed in loess and colluvium in the upper part and old unconsolidated moderately fine and fine textured tuffaceous sediments in the lower part. The climate is semiarid continental with a mean annual precipitation of 9 to 12 inches but can range to 14 inches when on south-facing slopes. The mean summer temperature is 60 to 66 degrees F. The mean winter temperature is 31 to 36 degrees F. The mean annual temperature ranges from 45 to 52 degrees F. The frost-free period is 90 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Day, Court, Lithgow, Ruckles, Searles, Tub and Willowdale soils. Day soils lack an argillic horizon. Lithgow soils have an ochric epipedon and have more than 35 percent rock fragments in the control section. Ruckles soils are clayey-skeletal have a lithic contact at 10 to 20 inches and are associated with basalt rimrock. Searles soils have a medium or moderately fine textured control section. Tub soils have a mollic epipedon over 20 inches thick. Willowdale soils are on flood plains and are medium textured.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: The principal use is for livestock grazing. Native plants are bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass, and Wyoming and basin big sagebrush.
DISTRIBUTION AND EXTENT: Central and east-central Oregon; MLRA 10. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Grant County, Oregon, 1970.
REMARKS: Diagnostic horizons and other features:
Mollic epipedon- the zone from 0 to 14 inches (A and 2Bt horizons.)
Argillic horizon- the zone from 5 to 21 inches (2Bt and 2Btk horizons)
Pale feature- clay increase of 15 percent (absolute) between the A and 2Bt horizons.
Aridic soil moisture regime.
Soft powdery secondary lime at 14 to 60 inches (2Btk, 2Bk1 and 2Bk2 horizons)
ADDITIONAL DATA: Characterization data for one profile (570-Oreg-23-1) by Oregon State University Laboratory (not published).