LOCATION OXBOW OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Palexerollic Durixerolls
TYPICAL PEDON: Oxbow silty clay loam, stony rangeland. (When described on May 11, 1973, the soil was slightly moist above the duripan. Colors are for moist soils unless otherwise noted.)
A1-- 0 to 10 centimeters (0 to 4 inches); black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; moderate thin and very thin platy structure; hard, friable, moderately sticky and moderately plastic; many roots; 5 percent stones; about 3 percent of surface covered with stones; slightly acid (pH 6.4); clear smooth boundary. (8 to 15 centimeters (3 to 6 inches) thick)
A2-- 10 to 20 centimeters (4 to 8 inches); black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many roots; common very fine tubular pores; 5 percent stones; slightly acid (pH 6.5); clear smooth boundary. (8 to 18 centimeters (3 to 7 inches) thick)
Bt1-- 20 to 30 centimeters (8 to 12 inches); very dark brown (10YR 2/2) silty clay loam, dark grayish brown (10YR 4/2) dry; moderate fine and very fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common roots; common very fine tubular pores; continuous distinct clay films; 1 percent stones and 4 percent cobbles; neutral (pH 6.6); abrupt smooth boundary. (0 to 15 centimeters (0 to 6 inches) thick)
Bt2-- 30 to 46 centimeters (12 to 18 inches); dark brown (10YR 3/3) stony clay, brown (10YR 4/3) dry; moderate medium prismatic and strong fine blocky structure; very hard, very firm, very sticky and very plastic; few roots; few fine and very fine tubular pores; continuous distinct clay films; 5 percent stones, 5 percent cobbles, and 5 percent gravel; neutral (pH 6.7); clear smooth boundary. (10 to 25 centimeters (4 to 10 inches) thick)
Btk-- 46 to 69 centimeters (18 to 27 inches); dark yellowish brown (10YR 4/4) stony clay, yellowish brown (10YR 5/4) dry; moderate fine subangular blocky structure; very hard, very firm, very sticky and very plastic; few roots; few very fine tubular pores; continuous prominent clay films; 15 percent carbonate-coated rock fragments; 5 percent stones, 5 percent cobbles, and 5 percent gravel; effervescent with disseminated lime; moderately alkaline (pH 8.1); abrupt smooth boundary. (20 to 30 centimeters (8 to 12 inches) thick)
2Bkqm-- 69 to 76 centimeters (27 to 30 inches); silica and carbonate cemented gravelly duripan with indurated laminar capping on horizontal surfaces. (15 to 50 centimeters (6 to 20 inches) thick)
3C-- 76 to 152 inches (30 to 60 inches); stratified sandy, gravelly, and strongly cemented layers.
TYPE LOCATION: Grant County, Oregon; 128 metrs (420 feet) west of Pine Creek Road, 2.3 kilometers (1.4 miles) south of junction with U.S. Highway 26, 10 kilometers (6 miles) east of the town of John Day, Oregon; 732 meters (2,400 feet) east and 701 meters (2,300 feet) south of the northwest corner of section 26, T. 13 S., R. 32 E. (Latitude 44 degrees, 24 minutes, 40 seconds North; Longitude 118 degrees, 50 minutes, 25 seconds West., NAD27, on the Prairie City USGS quadrangle)
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 11 to 13 degrees C. (51 to 56 degrees F.). Depth to the indurated duripan is 50 to 100 centimeters (20 to 40 inches). Up to 3 percent of surface is covered with rock fragments, dominantly stones. Depth to bedrock is over 152 centimeters (60 inches).
The A horizon has value of 4 or 5 dry and chroma of 1 or 2 moist and dry. It is silty clay loam, clay loam or loam with 25 to 35 percent clay. Rock fragments range from 5 to about 20 percent, of which 5 to 20 percent are cobbles and stones and 0 to 15 percent is gravel. Rock fragments are rounded.
The Bt2 and Btk horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 3 or 4 moist and chroma of 3 or 4 moist and dry. It is clay and has 50 to 60 percent clay. It has moderate or strong prismatic and blocky structure. The Btk horizon is slightly to strongly effervescent. Rock fragments range from 10 to 30 percent and consist of cobbles, stones and gravel. Rock fragments are rounded.
The duripan (2Bkqm horizon) is 15 to 50 centimeters (6 to 20 inches) thick. It has 30 to 80 percent gravel and cobbles. Stratified sandy, gravelly, and strongly cemented layers underlay the duripan. Rock fragments are rounded.
COMPETING SERIES: These are the Hibbard, Notchcorral, and Salisbury series. Hibbard soils are similar and occur in MLRA 10 which is characterized by having big sagebrush. The climate is different in terms of timing and distribution of precipitation even though the total is the same. Hibbard and Notchcorral soils have a mean annual soil temperature of less than 11 degrees C. (51 degrees F.). Notchcorral soils have bedrock below the duripan. Salisbury soils lack carbonate accumulation in the lower part of the argillic horizon and duripan.
GEOGRAPHIC SETTING: The Oxbow soils are on old fan terraces on slopes of 0 to 10 percent. Elevations range from 823 to 1280 meters (2,700 to 4,200 feet). The soils formed in mixed alluvial sediments. Mean annual precipitation is 36 to 46 centimeters (14 to 18 inches). Mean annual temperature is about 8 to 10 degrees C. (47 to 50 degrees F.). The average frost-free period is 90 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Belshaw (T), Oxwall, Prill, Starkey, Tub, Zweygardt (T) soils. Belshaw, Prill, Starkey, Tub, and Zweygardt soils lack a duripan. The Belshaw soils are on side slopes of hills, are very deep, and formed from volcanic tuff. Prill soils are on benches and side slopes of hills and are moderately deep to volcanic tuff. Starkey soils are on benches and side slopes of hills and are shallow to volcanic tuff. Oxwall soils are 25 to 50 centimeters (10 to 20 inches) deep to a duripan and are formed on old alluvial fans. Tub soils are on hillsides and are deep over volcanic tuff. The Zweygardt soils are on old fan terrace side slopes, are clayey-skeletal, and very deep.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Mainly range. Some of the less stony areas are semi-irrigated and used for hay production and pasture. Native vegetation includes bluebunch wheatgrass, Idaho fescue and Canby bluegrass, R009XY015OR, Clayey 14-17PZ.
DISTRIBUTION AND EXTENT: East-central Oregon; MLRA 9. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Grant County, Oregon, 1975.
REMARKS: Diagnostic horizons and other features:
Mollic epipedon - from 0 to 30 centimeters (0 to 12 inches)
Argillic horizon - from 30 to 69 centimeters (12 to 27 inches)
Indurated duripan at 69 centimeters (27 inches)
Palexerollic feature - 20 percent clay increase between the Bt1 and Bt2 horizon.
Xeric moisture regime
ADDITIONAL DATA: Characterization data on one profile (S70 Oreg-23-3) by Oregon State University Laboratory, published in the OSU Extension Service, Special Report 662, June, 1982.