LOCATION PIERSONTE OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Vitrandic Haploxerolls
TYPICAL PEDON: Piersonte channery ashy loam, woodland. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 1 inch to 0; slightly decomposed needles and twigs.
A1--1 to 11 inches; black (10YR 2/1) channery ashy loam, very dark brown (10YR 2/2) dry; weak very fine granular structure; loose, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular pores; 30 percent angular shale channers; neutral (pH 7.2); clear smooth boundary. (7 to 15 inches thick)
A2--11 to 28 inches; very dark brown (10YR 2/2) very channery ashy loam, very dark grayish brown (10YR 3/2) dry; weak very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular pores; 55 percent angular shale channers; neutral (pH 6.6); clear smooth boundary. (9 to 20 inches thick)
Bw1--28 to 51 inches; dark yellowish brown (10YR 4/4) very channery ashy loam, yellowish brown (10YR 5/4) dry; weak very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and medium roots; many very fine irregular pores; 55 percent angular shale channers; neutral (pH 6.6); clear smooth boundary. (15 to 30 inches thick)
Bw2--51 to 61 inches; dark yellowish brown (10YR 4/4) extremely channery ashy loam, yellowish brown (10YR 5/4) dry; massive; slightly hard, very friable, slightly sticky and slightly plastic; few medium roots; many very fine irregular pores; 70 percent angular shale channers; neutral (pH 6.6).
TYPE LOCATION: Grant County, Oregon; about 5 miles southwest of the town of Mt. Vernon; SW1/4SW1/4 sec. 12, T. 14 S., R. 29 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 42 to 47 degrees F. These soils are usually moist but are dry in the control section for 60 to 90 consecutive days during the four months following the summer solstice. The solum is slightly acid or neutral. Depth to fractured shale bedrock is over 60 inches. Base saturation by sum is over 75 percent throughout the profile. The mollic epipedon is 20 to 35 inches thick.
The A horizon has value of 2 or 3 moist, 2 or 3 dry and chroma of 1 or 2. It is ashy loam and has 20 to 40 percent shale fragments in the upper part and 35 to 50 percent in the lower part.
The upper part of the Bw horizon has value of 2 through 4 moist, 2 through 4 dry and chroma of 1 through 4. It is ashy loam or ashy clay loam with 18 to 30 percent clay and 50 to 70 percent shale fragments.
The lower part of the Bw horizon has value of 3 or 4 moist and 4 through 6 dry and chroma of 2 through 4 moist and dry. It is ashy loam, ashy clay loam or ashy sandy clay loam and has 50 to 80 percent shale fragments.
COMPETING SERIES: These are the Bearspring, Cassel, Cherrycreek, Eastpine, Egyptcreek, Fredonyer, Longs, Midpeak, Mineral, Peahke, Scoap, Shalrock, Shilting, Umatilla and Yellcreek series. Bearspring soils contain angular granitic rock fragments. Cassel soils are deep to a densic contact. Cherrycreek and Longs soils are deep to basalt (lithic contact). Eastpine, Egyptcreek, Fredonyer, Midpeak, Mineral, Peahke and Shalrock soils are moderately deep to bedrock. Scoap soils have rounded or subrounded rock fragments. Skilling and Yellcreek soils have mollic epipedon less than 20 inches thick. Umatilla soils have base saturation less than 75 percent in some part above 30 inches (Ultic).
GEOGRAPHIC SETTING: Piersonte soils are on mountains mainly on northerly slopes at elevations ranging from 3,500 to 5,500 feet. Slope is 35 to 75 percent. They formed in colluvium weathered from shale or schist and mixed with ash. The climate is subhumid with a mean annual precipitation of 16 to 30 inches. The mean annual temperature is 40 to 45 degrees F; the mean July temperature is about 63 degrees F, and the mean January temperature is about 25 degrees F. The frost-free period is 20 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hankins, Laycock, Logdell, McGarr and Tolo soils. Hankins soils have clay argillic horizons with less than 35 percent rock fragments. Logdell soils are very shallow to bedrock. McGarr soils are fine-loamy and are 20 to 40 inches deep to a lithic contact. Tolo soils are ashy over loamy. Laycock soils are less than 20 inches to a lithic contact.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Timber production with some grazing by livestock and game. Vegetation is mainly Douglas fir and ponderosa pine with an understory of pinegrass and elk sedge.
DISTRIBUTION AND EXTENT: Eastern Oregon; MLRA 43C. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Grant County, Oregon; 1975.
REMARKS: Diagnostic horizons and other features:
Mollic epipedon - 0 to 27 inches
Cambic horizon - 27 to 61 inches, cambic horizons meet Vitrandic Subgroup criteria throughout.
ADDITIONAL DATA: S97OR-023-028.