LOCATION PRAIRIE OREstablished Series
TAXONOMIC CLASS: Ashy over loamy, amorphic over isotic Xeric Vitricryands
TYPICAL PEDON: Prairie ashy sandy loam - woodland, on a 6 percent slope at 4700 feet elevation. (When described (7/23/85), the soil was moist below 22 inches. Colors are for moist soil unless otherwise noted).
Oi--0 to 3 inches; slightly decomposed litter of ponderosa pine, Douglas fir, and white fir
A1--3 to 10 inches; dark brown (10YR 3/3) ashy sandy loam, brown (10YR 4/3) dry; weak medium granular structure; slightly hard, friable, nonsticky and nonplastic; many very fine and fine roots; many very fine irregular pores; 5 percent gravel; neutral (pH 6.8); gradual smooth boundary.
A2--10 to 19 inches; dark yellowish brown (10YR 3/4) ashy sandy loam, brown (10YR 4/3) dry; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common fine, medium, and coarse roots; many fine irregular pores; 5 percent gravel; neutral (pH 7.0); gradual smooth boundary. (Combined thickness of the A horizon is 14 to 20 inches)
2Btb1--19 to 25 inches; dark brown (10YR 3/3) gravelly loam, brown (10YR 4/3) dry; strong medium subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; few medium and coarse roots; common very fine tubular pores; few faint clay films in pores and on ped faces; 15 percent gravel; neutral (pH 7.0); clear wavy boundary.
2Btb2--25 to 40 inches; brown (7.5YR 4/2) cobbly loam, brown (7.5YR 5/4) dry; strong medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few coarse roots; few fine irregular pores; many faint clay films in pores and on ped faces; 20 percent gravel, 5 percent cobbles and 5 percent stones; neutral (pH 7.2); clear wavy boundary. (Combined thickness of the 2Btb horizon is 6 to 26 inches)
2Cr--40 inches; weathered basalt.
TYPE LOCATION: Jefferson County, Oregon; on USFS road 1140-680, 0.4 miles from junction with USFS road 1140-610, southwest quarter of the southeast quarter of section 13, T. 12 S., R. 9 E. (Latitude 44 degrees, 31 minutes, 30 seconds N, Longitude 121 degrees, 35 minutes, 56 seconds W)
RANGE IN CHARACTERISTICS: The soil moisture control section is usually moist but is dry in all parts for 45 to 60 consecutive days within the 4 months that follow the summer solstice. The mean annual soil temperature is 41 to 45 degrees F. The mean summer soil temperature is 43 to 47 degrees F. Depth to the buried argillic horizon is 14 to 20 inches. Depth to a paralithic contact is 20 to 40 inches.
The 0i horizon is 2 to 4 inches thick except where disturbed.
The A horizon has a hue of 10YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist or dry. It is a sandy loam with 10 to 18 percent field estimated clay and 0 to 10 percent gravel. It has 50 to 80 percent glass and glass coated aggregates.
The 2Btb horizons have hue of 10YR and 7.5YR with value of 3 or 4 moist and 4 or 5 dry and chroma of 2 to 4 moist and 3 or 4 dry. It is gravelly or cobbly loam with 18 to 27 percent field estimated clay. It has 10 to 20 percent gravel and 5 to 15 percent cobbles and stones. Total rock fragments are 15 to 35 percent.
COMPETING SERIES: These are the Almac, Gap, and Shanahan series. Almac soils are dry for 60 to 75 consecutive days, have a mean annual soil temperature of 39 to 41 degrees F, and have fine sandy loam or sandy loam in the lower part of the particle-size control section. Gap soils are 40 to 60 inches to bedrock. Shanahan soils are very deep, lack a buried argillic horizon, and contain 0 to 5 percent field estimated clay in the ash mantle.
GEOGRAPHIC SETTING: The Prairie soils are on mountains at elevations of 4000 to 5000 feet. They formed in ash over colluvium and residuum from weathered ash flow tuffs, basalt or andesite. The climate is characterized by cold, wet winters and cool, dry summers. The mean annual precipitation is 25 to 35 inches, falling mostly as snow. The mean annual temperature is 40 to 44 degrees F. The frost-free period is 10 to 50 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Gap and the Glaze soils. Glaze soils are deep to bedrock and are ashy over loamy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability.
USE AND VEGETATION: These soils are used for timber production, wildlife habitat, recreation, and watershed. Potential native vegetation is ponderosa pine, Douglas fir, white fir, snowberry, and pinegrass.
DISTRIBUTION AND EXTENT: East slope of the Cascade Mountains of central Oregon; MLRA 6. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Jefferson County (Upper Deschutes River Area), Oregon, 1992.
REMARKS: Diagnostic horizons and features in this pedon are:
Ochric epipedon
Argillic horizon (buried) - from 19 to 40 inches (2Btb horizons).
Andic soil properties - the upper 16 inches of the mineral soil meets andic soil properties criteria (2c).
Particle-size control section - the upper mantle (3 - 19 inches) has andic soil properties and 15-bar water content of less than 12 (dried). This is based on geographically associate soils. The lower part from 19 to 40 inches does not have andic soil properties an has less than 30 percent glass.