LOCATION BELSHAW ORTentative Series
TAXONOMIC CLASS: Fine, smectitic, mesic Typic Palexerolls
TYPICAL PEDON: Belshaw cobbly silt loam - rangeland, on a 5 percent slope at an elevation of 2,800 feet. (When described on October 21, 2002, the soil was dry throughout. Colors are for moist soils unless otherwise noted.)
A--0 to 2 inches; very dark gray (10YR 3/1) cobbly silt loam, gray (10YR 5/1) dry; weak thin platy structure; soft, very friable, slightly sticky and slightly plastic; few fine and many very fine roots; few fine and common very fine irregular pores; 10 percent cobbles and 5 percent gravel; neutral (pH 7.0); abrupt wavy boundary. (2 to 10 inches thick)
2Bt--2 to 11 inches; dark brown (7.5YR 3/2) cobbly clay, dark brown (7.5YR 3/2) dry; moderate medium prismatic structure; very hard, very firm, and very sticky and very plastic; few coarse, fine, and very fine roots; few very fine tubular pores; many prominent clay films on ped faces and in pores; 10 percent cobbles and 10 percent gravel; moderately alkaline (pH 8.2); clear wavy boundary. (6 to 14 inches thick)
2Btk--11 to 23 inches; very pale brown (10YR 7/4) cobbly clay loam, very pale brown (10YR 8/2) dry; moderate medium and coarse subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few very fine tubular pores; many faint clay films on ped faces; strongly effervescent; lime coating all rock fragments; 15 percent cobbles and 15 percent gravel; moderately alkaline (pH 8.4); gradual wavy boundary. (0 to 15 inches thick)
2Bk1--23 to 34 inches; very pale brown (10YR 7/4) very cobbly sandy loam, very pale brown (10YR 8/2) dry; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; violently effervescent; lime completely coating all rock fragments; 20 percent cobbles and 20 percent gravel; strongly alkaline (pH 8.6); gradual wavy boundary.
2Bk2--34 to 60 inches; brown (10YR 5/3) very cobbly loamy coarse sand, very pale brown (10YR 7/3) dry; single grain; loose, nonsticky and nonplastic; strongly effervescent; lime coating most of the rock fragments; 25 percent cobbles and 15 percent gravel; moderately alkaline (pH 8.4).
TYPE LOCATION: Grant County, Oregon, about 11 miles west of the town of Mt. Vernon; 500 feet north and 800 feet west of the SE corner of section 9, T. 13 S., R. 28 E. (Latitude 44 degrees, 26 minutes, 55 seconds North and Longitude 119 degrees, 20 minutes, 58 seconds West)
RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in all parts of the moisture control section for 70 to 90 days within the 4 months following the summer solstice. The mean annual soil temperature is 47 to 52 degrees. Depth to bedrock is more than 60 inches. The mollic epipedon is 10 to 20 inches. Depth to the argillic horizon is 2 to 10 inches. There is an absolute increase in clay between the A and the 2Bt horizons of 15 percent or more.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 or 2 moist and dry. It is silt loam with 20 to 27 percent clay. It has 0 to 15 percent stones, 0 to 10 percent cobbles, and 5 to 10 percent gravel. Soil reaction is neutral or slightly alkaline.
The 2Bt horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 3 to 5 dry, and chroma of 2 or 3 moist and dry. It is clay or silty clay with 40 to 50 percent clay. It has 0 to 10 percent cobbles and 0 to 10 percent gravel.
The 2Btk horizon, when present, has value of 5 to 7 moist, 6 to 8 dry, and chroma of 2 to 4 moist and dry. It is clay loam with 27 to 40 percent clay. It has 0 to 15 percent cobbles and 0 to 15 percent gravel.
The 2Bk horizon has hue of 10YR or 2.5Y, value of 4 to 7 moist, 6 to 8 dry, and chroma of 2 to 4 moist and dry. It is loam, coarse sandy loam, or loamy coarse sand with 5 to 25 percent clay. It has 10 to 25 percent cobbles and 0 to 20 percent gravel. Soil reaction is moderately or strongly alkaline.
COMPETING SERIES: These are the Alibi, Coleman, Dry Creek, Lasere, Pomponio (T), Pritchard, Succor, and Tutuilla series. Alibi soils are moderately deep to rhyolite bedrock and lack secondary carbonates. Coleman soils are moderately well drained and lack secondary carbonates. Dry Creek soils have an argillic horizon that is moderately acid to neutral in its reaction and have a calcium carbonate equivalent that exceeds 15 percent. Lasere soils are moderately deep to basalt or tuff and are slightly acid or neutral throughout. Pritchard soils have an argillic horizon at a depth of 10 to 20 inches and its profile only displays minimal evidence of secondary carbonates. Succor soils have a Bq horizon. Pomponio soils are moderately deep to shale. Tutuilla soils are deep to sedimentary rock and lack secondary carbonates.
GEOGRAPHIC SETTING: Belshaw soils are on rolling hills and south slopes. They formed in colluvium derived from tuffaceous sediments with an influence of ash and loess in the surface. Slopes are 2 to 50 percent. Elevation is 2,200 to 4,600 feet. At higher elevations, these soils are only on south-facing slopes. The climate is characterized by cool, wet winters and hot, dry summers. The mean annual precipitation is 12 to 18 inches. The mean annual temperature is 45 to 50 degrees F. The frost-free period is 80 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kishwalk, Tanksel, Tub, and Waterbury soils. Kishwalk, Tanksel, and Waterbury soils are found on basaltic hillsides above tuffaceous sediments and are clayey-skeletal. Also, Kishwalk soils are moderately deep to basalt bedrock whereas Waterbury soils are shallow to basalt. Tanksel soils are on north slopes, have ash in the surface horizons, and are moderately deep to bedrock. Tub soils are also formed in tuffaceous sediments, but Tub soils are on alluvial fans and north slopes, are pachic, and lack the abrupt textural change.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is very slow.
USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. The native vegetation is bluebunch wheatgrass, Sandberg's bluegrass, and big sagebrush.
DISTRIBUTION AND EXTENT: East-central Oregon, MLRA 10. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Grant County Area, Oregon, 2003. The name is derived from Belshaw Creek located about 8 miles west of the town of Mt. Vernon.
REMARKS: Diagnostic horizons recognized in this pedon:
Mollic epipedon - from the surface to a depth of 11 inches (A and 2Bt horizons)
Argillic horizon - 2 to 23 inches (2Bt and 2Btk horizons)
Pale feature - argillic horizon with a clayey particle-size class and an abrupt upper boundary (2Bt horizon) with a 20 percent increase in clay
Particle size control section - 2 to 22 inches (2Bt and most of the 2Btk horizons)
Soil moisture regime - xeric bordering aridic