LOCATION BRIDGECREEK OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Palexerolls
TYPICAL PEDON: Bridgecreek silt loam, rangeland. (Colors are for moist soil unless otherwise noted.)
A1--0 to 4 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; weak fine subangular blocky structure parting to moderate fine and medium granular; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine irregular pores; 5 percent gravel; neutral (pH 6.6); gradual wavy boundary. (4 to 8 inches thick)
A2--4 to 10 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine irregular pores; 5 percent gravel; neutral (pH 6.6); clear wavy boundary. (0 to 6 inches thick)
BA--10 to 16 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; strong fine and medium subangular blocky structure; slightly hard, friable, sticky and slightly plastic; common fine roots; common very fine tubular pores; 5 percent gravel; neutral (pH 6.8); clear wavy boundary. (0 to 6 inches thick)
Bw1--16 to 20 inches; dark brown (10YR 3/3) silty clay loam, brown (10YR 5/3) dry; strong fine subangular blocky structure; hard, firm, sticky and slightly plastic; common fine roots; common very fine tubular pores; 5 percent gravel; neutral (pH 6.8); gradual wavy boundary. (4 to 9 inches thick)
Bw2--20 to 26 inches; dark yellowish brown (10YR 3/4) silty clay loam; pale brown (10YR 6/3) dry; strong fine subangular blocky structure; hard, firm, sticky and slightly plastic; common fine roots; 5 percent gravel and 5 percent cobbles; neutral (pH 7.0); few very fine tubular pores; abrupt wavy boundary. (2 to 7 inches thick)
2Bt--26 to 32 inches; dark brown (7.5YR 3/3) clay, dark brown (7.5YR 3/4) dry; moderate medium prismatic structure parting to strong medium and coarse angular blocky; very hard, very firm, sticky and plastic; few fine roots; few very fine tubular pores; 5 percent gravel and 5 percent cobbles; many thick clay films in pores and and on ped faces; neutral (pH 7.0); abrupt wavy boundary. (6 to 12 inches thick)
2Cr--32 inches; semiconsolidated light yellowish brown (10YR 6/4) tuffaceous material; 30 percent pockets of strong brown (7.5YR 4/6) clay loam material throughout.
TYPE LOCATION: Umatilla County, Oregon; 50 feet east of the road in SE1/4 NW1/4 section 12, T. 6 S., R. 30 E.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry throughout between depths of 4 to 12 inches for 60 to 90 consecutive days following the summer solstice. The mean annual soil temperature is 44 to 47 degrees F. Depth to the paralithic contact ranges from 20 to 40 inches. Thickness of the mollic epipedon ranges from 15 to 20 inches.
The A horizon has value of 2 or 3 moist and 4 or 5 dry and chroma of 1 or 2 moist and dry.
The Bw horizon has value of 3 or 4 moist and chroma of 3 or 4 moist. It has 30 to 40 percent clay.
The 2Bt horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist and dry. It has 45 to 60 percent clay. There is an increase in clay content of 15 percent or more (absolute) within a vertical distance of 1 inch at the upper boundary.
In some pedons there is a thin silty clay loam layer immediately above the paralithic contact.
COMPETING SERIES: These are the Deer Creek, Goodington (T), Harkers, Norcan, Rands, and Zumwalt (T) soils. The Deer Creek, Goodington, Harkers, Norcan and Rands soils are over 40 inches deep to bedrock. The Zumwalt soils are 20 to 40 inches deep to a lithic contact.
GEOGRAPHIC SETTING: Bridgecreek soils are on terraces at elevations of 3,800 to 4,300 feet. Slopes range from 1 to 35 percent. The soils formed in residuum from tuffaceous material with influence from loess and volcanic ash in the upper part. The mean annual temperature is 40 to 45 degrees F., and the mean annual precipitation is 15 to 25 inches. The frost-free period is 50 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anatone, Bocker, Gwin, Kahler, Klicker and Tolo soils. Anatone, Bocker and Gwin soils are less than 20 inches deep to hard basalt and are skeletal. Klicker soils are skeletal and have a lithic contact. Kahler soils are loamy and are deeper than 60 inches to basalt. Tolo soils have a mantle of volcanic ash over 20 inches thick.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; very slow permeability.
USE AND VEGETATION: Bridgecreek soils are used for range and wildlife habitat. Native vegetation is Idaho fescue, prairie junegrass, bluebunch wheatgrass, and Sandberg bluegrass.
DISTRIBUTION AND EXTENT: The series is of moderate extent and occurs in interior valleys of northeastern Oregon.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Umatilla County, Oregon, 1985.