LOCATION THADER OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic Typic Humicryods
TYPICAL PEDON: Thader very cobbly loam, forested. (Colors are for moist soil unless otherwise noted.)
O1--5 to 4 inches; loose litter of needles, twigs, cones, leaves, etc.
O2--4 inches to 0; black (10YR 2/1) decomposing organic matter; many roots; extremely acid (pH 4.0); abrupt wavy boundary.
E--0 to 2 inches; dark gray (10YR 4/1) very cobbly fine sandy loam, gray (10YR 6/1) dry; massive; soft, friable, nonsticky and slightly plastic; many fine medium and coarse roots; many fine and very fine irregular pores; 50 percent cobbles and gravel; extremely acid (pH 4.3); abrupt wavy boundary. (1 to 5 inches thick)
Bhs1--2 to 4 inches; dark reddish brown (5YR 2/2) very cobbly loam, brown and dark brown (7.5YR 4/4 and 3/3) dry; massive; hard, firm, nonsticky and slightly plastic; common fine, medium and coarse roots; many fine and very fine irregular pores; 60 percent angular stones, cobbles, and gravel; very strongly acid (pH 5.0); abrupt wavy boundary resulting in this horizon being intermittent (30 percent present). (0 to 5 inches thick)
Bhs2--4 to 17 inches; dark brown (7.5YR 3/3) very cobbly silt loam, brown (7.5YR 4/4) dry and crushed; variegated with dark yellowish brown (10YR 4/4) and dark reddish brown (5YR 3/4); weak very fine and fine subangular blocky and granular structure; slightly hard, friable and firm, slightly sticky and slightly plastic; many fine medium and coarse roots; many fine and very fine tubular and irregular pores; 70 percent stones, cobbles and gravel; strongly acid (pH 5.1); clear wavy boundary. (10 to 20 inches thick)
BC--17 to 28 inches; dark brown (7.5YR 4/4) very cobbly silt loam, light yellowish brown (10YR 6/4) dry and crushed; variegated with dark yellowish brown (10YR 4/4), brown (10YR 5/3) and grayish brown (10YR 5/2); massive; slightly hard, slightly firm, slightly sticky and slightly plastic; few fine, medium and coarse roots; many fine and very fine irregular pores; 70 percent angular stones, cobbles and gravel strongly acid (pH 5.4); abrupt wavy boundary. (7 to 20 inches thick)
2R--28 inches; fractured basalt and andesite. TYPE LOCATION: Clackamas County, Oregon; 100 feet northeast of the Bull Run Lake Road, 1.7 miles southwest of the switchback above Bull Run Lake; NE1/4 SW1/4 section 29, T.1S., R.8E., W.M.
RANGE IN CHARACTERISTICS: The soils are usually moist and are dry for less than 45 consecutive days between depths of 8 to 24 inches. The mean annual soil temperature ranges from 38 degrees to 45 degrees F. The mean summer soil temperature is less than 47 degrees F. with an O horizon. Depth to bedrock ranges from 20 to 40 inches.
The E horizon has value of 4 or 5 moist, 6 or 7 dry, and chroma of 1 or less. It is fine sandy loam or loam. These are 30 to 50 percent cobbles and 15 to 35 percent pebbles.
The Bhs horizon has hue of 2.5YR or 5YR and value of 2 or 3 moist and 4, 5 and 6 dry. The Bhs horizon is dominantly dark brown (7.5YR 3/3, 3/2), but it is variegated with colors in hue of 10YR through 5YR, value of 3 or 4 moist and chroma of 2 through 4. Organic matter in the upper 4 inches of the Bhs horizon is more than 10 percent. The Bhs horizon is loam or silt loam and has 45 to 70 percent rock fragments.
The C horizon, where present, is similar in color to the BC horizon but without the variegations.
COMPETING SERIES: There are no competing series in this family. Similar soils include Lastance series. Lastance soils are more than 40 inches deep to bedrock.
GEOGRAPHIC SETTING: The Thader soils are on major ridges in the Cascade Mountains between elevations of 3,000 and 5,000 feet. Slopes range from 0 to 90 percent. The soil formed in colluvium and residuum weathered from olivine basalts and olivine-bearing andesites of the Cascade Andesite Formation. The climate is humid. The mean annual precipitation ranges from 90 to 145 inches, falling as rain in the early autumn and late spring, and snow in the late autumn, winter and early spring. Rainfall amounts are relatively low in the summer. The average January temperature is 29 degrees F. The average July temperature is 56 degrees F. The mean annual air temperature is 38 degrees to 45 degrees F. The frost-free period is 10 to 30 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Goodlow, Kinzel and Oneonta soils and the competing Lastance soils. Goodlow, Kinzel and Oneonta soils lack spodic horizons and are deeper than 40 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately rapid permeability.
USE AND VEGETATION: The primary uses of the Thader soils are for timber production and for recreation and wildlife. Overstory vegetation is Douglas-fir, hemlock, silver fir, noble fir, and western redcedar. The dominant understory vegetation is huckleberry, rhododendron, and beargrass.
DISTRIBUTION AND EXTENT: Cascade Mountains of northwest Oregon. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Multnomah County, Oregon (Bull Run, Sandy Area), 1976.
ADDITIONAL DATA: Characterization data for one pedon (FS62-Ore-045-15 (1-6)) by Oregon State University. (Unpublished)
NSTH 17, RECLASSIFICATION ONLY, 3/95