LOCATION ELDERFLAT ORTentative Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vitrandic Argixerolls
TYPICAL PEDON: Elderflat ashy loam - rangeland, on a 3 percent slope at an elevation of 3,450 feet. (When described on October 5, 2004, the soil was dry to 10 inches and slightly moist below 10 inches. Colors are for moist soil unless otherwise noted.)
A--0 to 2 inches; dark brown (10YR 3/3) ashy loam, brown (10YR 4/3) dry; moderate very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and many very fine roots; few fine and common very fine irregular pores; 10 percent fine gravel; slightly alkaline (pH 7.4); clear smooth boundary. (2 to 9 inches thick)
Bw--2 to 10 inches; dark brown (7.5YR 3/3) ashy clay loam, brown (7.5YR 4/3) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; slightly hard, friable, slightly sticky and moderately plastic; common very fine roots; common very fine tubular pores; 10 percent fine gravel; slightly alkaline (pH 7.5); gradual wavy boundary. (5 to 13 inches thick)
2Bt1--10 to 23 inches; dark brown (7.5YR 3/3) clay, brown (7.5YR 4/3) dry; moderate medium and coarse subangular blocky structure; moderately hard, firm, very sticky and very plastic; few very fine roots; few very fine tubular pores; continuous distinct clay films on ped faces; 10 percent fine gravel; slightly alkaline (pH 7.6); clear wavy boundary.
2Bt2--23 to 28 inches; dark brown (7.5YR 3/3) cobbly clay, brown (7.5YR 4/3) dry; moderate fine and medium subangular blocky structure; hard, very firm, very sticky and very plastic; few very fine tubular pores; continuous distinct clay films on ped faces; 15 percent cobbles and 5 percent gravel; slightly alkaline (pH 7.6); abrupt wavy boundary. (Combined thickness of the 2Bt horizon is 10 to 20 inches.)
2R--28 inches; basalt.
TYPE LOCATION: Grant County, Oregon, located about 10 miles NW of the community of Ritter along the southern edge of Elder Flat; 800 feet north and 800 feet east of the SW corner of section 13, T. 7 S., R. 28 E. (Latitude 44 degrees, 57 minutes, and 30 seconds N. and Longitude 119 degrees, 19 minutes, and 17 seconds W.)
RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in all parts of the moisture control section for 45 to 70 consecutive days within the four months that follow the summer solstice. The mean annual soil temperature is 47 to 52 degrees F. Depth to bedrock is 20 to 40 inches. The mollic epipedon is 20 to 30 inches thick and includes the upper part of the 2Bt horizon. Hue is 7.5YR or 10YR throughout. The particle-size control section averages 35 to 50 percent clay and averages less than 15 percent rock fragments. The A and Bw horizons have 5 to 15 percent volcanic glass and 0.4 to 0.8 percent acid oxalate extractable aluminum plus one-half iron.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It is ashy loam with 18 to 25 percent clay. It has 0 to 10 percent gravel.
The Bw horizon has colors similar to the A horizon. It is ashy loam or ashy clay loam with 25 to 35 percent clay. It has 0 to 10 percent gravel.
The 2Bt horizon has value of 3 or 4 moist and 4 or 5 dry, and chroma of 3 or 4 moist and dry. It is clay loam or clay with 35 to 50 percent clay. It has 0 to 15 percent gravel in the upper part of the 2Bt horizon and 0 to 15 percent cobbles and 0 to 5 percent gravel in the lower part. The lower part of the 2Bt horizon has less than 1 percent organic matter.
COMPETING SERIES: These are the Bedron and Jorn series. Bedron soils are very deep. Jorn soils have a paralithic contact at 20 to 40 inches.
GEOGRAPHIC SETTING: Elderflat soils are on plateaus and benches and have slopes of 2 to 20 percent. They formed in fine-textured colluvium and residuum derived from basalt. Usually Elderflat soils are found as mounds in patterned ground topography. Slopes are 2 to 20 percent. The climate is characterized by cool, wet winters and hot, dry summers. Elevation is 2,500 to 4,000 feet. The mean annual precipitation is 12 to 18 inches, and 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 Akerite, Gaib, Hankins, Rockly, and Top soils. Akerite soils are in concave positions on plateaus, are ashy over loamy, and are moderately well drained. Gaib soils are found in convex areas of plateaus, are loamy-skeletal, and are shallow to bedrock. Hankins soils are on gently rolling plateaus and benches, are very deep, and have an O horizon. Rockly soils are very shallow, loamy-skeletal, and are found in complex with Elderflat soils on plateaus. Top soils are found on adjacent north facing side slopes, are very deep, and have an O horizon.
DRAINAGE AND PERMEABILITY: Well drained; permeability is slow.
USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. The native potential vegetation is bluebunch wheatgrass. The ecological site is JD Clayey 12 to 16 PZ (RO10XB027OR).
DISTRIBUTION AND EXTENT: East-central Oregon, MLRA-10. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Grant County, Oregon, 2006. The name is derived from Elder Flat, a large plateau northwest of the community of Ritter.
REMARKS: Diagnostic horizons and features in this pedon are:
Mollic epipedon (pachic) - from the surface to 23 inches
Argillic horizon - from 10 to 28 inches
Lithic contact - at 28 inches
Particle size control section - from 10 to 28 inches
COLE is 5.49
Xeric moisture regime