LOCATION MT. HOOD OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic Typic Haplocryods
TYPICAL PEDON: Mt. Hood stony fine sandy loam, forested. (Colors are for moist soil unless otherwise noted.)
1/2 inch to 0; needles, twigs, cones, etc.
A2--0 to 1 inch; dark gray (10YR 4/1) stony fine sandy loam, light gray (10YR 6/1) dry; single grained; loose, nonsticky and nonplastic; trace of coarse fragments; common fine, medium and coarse roots; many fine and very fine irregular pores; strongly acid (pH 5.4); abrupt irregular boundary (tongues to 3 inches). (1/2 to 4 inches thick)
B2ir--1 to 9 inches; dark brown (7.5YR 3/4) stony fine sandy loam, brown (10YR 5/4) dry; variegated with yellowish red (5YR 4/6), dark grayish brown (10YR 4/2), and dark yellowish brown (10YR 4/4); massive; soft and slightly hard, friable, nonsticky and nonplastic; 20 percent stones, cobbles and pebbles; many fine and medium roots; many very fine and fine irregular pores; medium acid (pH 5.9); clear wavy boundary. (4 to 12 inches thick)
B3ir--9 to 23 inches; dark yellowish brown (10YR 4/4) very cobbly fine sandy loam, light yellowish brown (10YR 6/4) dry; variegated with brown (7.5YR 4/4), strong brown (7.5YR 5/6), and grayish brown (10YR 5/2); massive; slightly hard, friable, nonsticky and nonplastic; 55 percent cobbles, pebbles, and stones; common fine and medium roots; many fine and very fine irregular and tubular pores; medium acid (pH 6.0); gradual wavy boundary. (6 to 20 inches thick)
C--23 to 40 inches; dark yellowish brown (10YR 4/4), very cobbly fine sandy loam, pale brown (10YR 6/3) dry; massive; hard, firm, nonsticky and nonplastic; 75 percent cobbles, pebbles and stones; common fine and medium roots; many very fine and fine irregular pores; slightly acid (pH 6.1).
TYPE LOCATION: Clackamas County, Oregon; along the Still Creek road, 1/4 mile northwest of the Sherar Burn road junction, SW1/4 NW1/4 section 25, T.3S., R.8 1/2E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 40 percent to 47 degrees F. The mean summer soil temperature is less than 47 degrees F. with an O horizon and full shade. The soils have a udic moisture regime but have a short dry period of less than 45 consecutive days during the summer. Depth to bedrock is 60 inches or more. The solum ranges from 12 to 30 inches thick. The 10- to 40-inch control section is fine sandy loam or sandy loam and has less than 10 percent clay and averages 35 to 70 percent rock fragments, dominantly cobblestones.
The A2 horizon has value of 4 or 5 moist, and 6 or 7 dry, and chroma of 1 or less. It is fine sandy loam, loam or silt loam. Stones cover up to 0.1 percent of the surface. Rock fragments range from 5 to 40 percent by volume. This horizon is strongly or very strongly acid.
The B2ir horizon has dominant hue of 7.5YR but variegated with 10YR and 5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 2 through 6 moist and dry. Rock fragments range from 30 to 60 percent and are dominantly cobblestones. This horizon is medium or strongly acid.
The C horizon has value of 5 or 6 dry and chroma of 3 or 4 moist and dry. It has loose to hard and friable or firm consistence. It has 50 to 80 percent rock fragments, dominantly cobblestones. This horizon is medium or slightly acid.
COMPETING SERIES: These are the Dinzer, Evaro, Homestead, Lastance and Tenex series. Evaro, Homestead, and Tenex soils have drier moisture regimes than udic. Also, Evaro soils have A2 horizons 5 to 15 inches thick and the Homestead soils have a thin loess mantle. Dinzer soils have intermittent A2 horizons less than 1/2 inch thick and lack the variegated colors in hue of 5YR. Lastance soils have firm and very firm consistence and hue of 5YR or 2.5YR throughout the upper part of the spodic horizon.
GEOGRAPHIC SETTING: Mt. Hood soils are on hillsides in glaciated valleys of the Cascade Mountains at elevations of 3,500 to 6,000 feet. Slope gradients range from 5 to 80 percent. The soils formed in glacial till weathered mostly from porphyritic andesitic and basaltic rocks of late Pleistocene origin. The climate is humid and cool. The mean annual precipitation ranges from 90 to 125 inches. The mean annual temperature ranges from 38 degrees to 45 degrees F.; the average January temperature is 27 degrees F.; and the average July temperature is 57 degrees F. The frost-free season is less than 50 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barlow soils. Barlow soils have less than 35 percent rock fragments in the 10- to 40-inch control section.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately rapid permeability.
USE AND VEGETATION: Timber production, recreation, and wildlife. Vegetation is Douglas-fir, silver fir, western hemlock, mountain hemlock, lodgepole pine, western white pine, western red cedar, Alaska yellow cedar, huckleberry, rhododendron, and beargrass.
DISTRIBUTION AND EXTENT: Cascade Mountains in northern Oregon. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Clackamas County, Oregon (Bull Run, Sandy Area), 1964.
ADDITIONAL DATA: Characterization data on one pedon FS62Oreg-045-19 (1-4) by Oregon State University. (Unpublished)
NSTH 17, RECLASSIFICATION ONLY, 3/95