LOCATION PILOT ROCK OREstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Haploxerollic Durixerolls
TYPICAL PEDON: Pilot Rock silt loam, cultivated. (Colors are for moist conditions unless otherwise noted.)
Ap1--0 to 4 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine irregular pores; neutral (pH 7.0); clear wavy boundary. (1 to 6 inches thick)
Ap2--4 to 10 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine tubular pores; neutral (pH 7.2); clear wavy boundary. (4 to 8 inches thick)
Bw--10 to 20 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; weak medium prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine tubular pores; mildly alkaline (pH 7.8); clear wavy boundary. (5 to 18 inches thick)
Bk--20 to 27 inches; dark brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; weak fine and medium prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine tublar pores; slightly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (2 to 12 inches thick)
2Ckqm--27 to 45 inches; very pale brown (10YR 7/3) very gravelly silica and lime cemented duripan, white (10YR 8/2) dry; massive; indurated in the upper part with laminar cap and strongly cemented below; extremely hard, extremely firm; strongly effervescent; strongly alkaline (pH 8.6); abrupt wavy boundary. (15 to 40 inches thick)
2Ck1--45 to 51 inches; pale brown (10YR 6/3) very gravelly sandy loam, light gray (10YR 7/2) dry; massive; hard, firm, nonsticky and nonplastic; 5 percent cobbles and 40 percent gravel; strongly effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (0 to 20 inches thick)
2Ck2--51 to 60 inches; very pale brown (10YR 7/3) very gravelly sand, white (10YR 8/2) dry; single grained, loose, nonsticky and nonplastic; 10 percent cobbles and 45 percent gravel; strongly effervescent; strongly alkaline (pH 8.8).
TYPE LOCATION: Umatilla County, Oregon; east of Highway 395 in the SE1/4 NE1/4 SW1/4 section 3, T. N., R. 32 E.
RANGE IN CHARACTERISTICS: Depth to the duripan is 20 to 40 inches. The mollic epipedon is 10 to 20 inches thick. These soils are usually moist but are dry for 60 to 80 consecutive days between 4 and 12 inches within the three-month period following the summer solstice. The particle-size control section is silt loam with 10 to 18 percent clay and less than 15 percent coarser than very fine sand.
The A horizon has chroma of 2 or 3 moist and dry. It is weak or moderate platy and granular or weak fine subangular blocky structure.
The Bw horizon has value of 4 or 5 dry and 3 or 4 moist and chroma of 2 or 3 moist and dry. It is weak fine, medium or coarse prismatic or medium or coarse subangular blocky structure.
The Bk horizon has value of 6 or 7 dry and 4 or 5 moist and chroma of 1 through 4 moist and dry. It is moderately to strongly alkaline.
The duripan is indurated in the upper 1 to 5 inches and is weakly to strongly cemented below. It grades to loose very or extremely gravelly sand many feet thick.
COMPETING SERIES: This is the Endicott series. The Endicott series lacks the very gravelly sand 2C horizons.
GEOGRAPHIC SETTING: Pilot Rock soils are on fan terraces at elevations of 1100 to 2100 feet. Slopes are 1 to 40 percent. Summers are hot and dry and winters are cool and moist. The mean annual temperature is 50 to 53 degrees F., and mean annual precipitation is 12 to 16 inches. The frost-free period is 140 to 165 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Anderly, Lickskillet, McKay and Walla Walla soils. Anderly soils are moderately deep to basalt. Lickskillet soils are skeletal and less than 20 inches to basalt. McKay soils have a calcic horizon. Walla Walla soils are deep to basalt or a duripan.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability above the duripan and very slow within the duripan.
USE AND VEGETATION: These soils are used for dryland small grains. Other uses include irrigated small grains, alfalfa, hay and pasture, range, homesite development and wildlife habitat. Native vegetation includes bluebunch wheatgrass, Sandberg bluegrass, Idaho fescue and related shrubs and forbs.
DISTRIBUTION AND EXTENT: Northeastern Oregon. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Umatilla County, Oregon, 1937.
NSTH 17, RECLASSIFICATION ONLY, 3/95