LOCATION OHOP WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Vitrandic Dystrudepts
TYPICAL PEDON: Ohop very gravelly loam - forested. (Colors are for moist soil unless otherwise indicated. Textures are apparent field textures.)
Oi--0 to 2 inches; partially decomposed needles, twigs, and fine matted roots.
A-2 to 9 inches; dark grayish brown (10YR 4/2) very gravelly ashy loam, light brownish gray (10YR 6/2) dry; moderate medium granular structure; slightly hard, friable, slightly sticky, nonplastic; many fine, very fine, and medium roots; 40 percent pebbles; slightly acid (pH 6.2); clear smooth boundary. (3 to 9 inches thick.)
Bw--9 to 18 inches; dark brown (10YR 3/3) very gravelly ashy loam, light brownish gray (10YR 6/2) dry; moderate medium subangular blocky parting to moderate medium granular structure; slightly hard, friable, slightly sticky, nonplastic; many fine and very fine roots; 40 percent pebbles, 10 percent cobbles; moderately acid (pH 5.8); gradual smooth boundary. (8 to 19 inches thick)
BC--18 to 30 inches; brown (10YR 4/3) extremely gravelly ashy sandy loam, pale brown (10YR 6/3) dry; common medium distinct yellowish brown (10YR 5/6) mottles, brownish yellow (10YR 6/6) dry; moderate medium subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; few medium roots, 50 percent pebbles, 10 percent cobbles, moderately acid (pH 5.6); gradual smooth boundary. (8 to 12 inches thick)
Cd--30 to 60 inches; brown (10YR 4/3) extremely gravelly sandy loam, light gray (10YR 7/2) dry; massive; very hard, firm, nonsticky, nonplastic, 50 percent pebbles, 20 percent cobbles; strongly acid (pH 5.4).
TYPE LOCATION: Snoqualmie Pass Area, Pierce County, Washington, 200 feet south of St. Regis Paper Company King Creek Access Road, about 2,300 feet south and 1,600 feet east of the northwest corner of sec. 17, T. 17 N., R. 6 E.
RANGE IN CHARACTERISTICS: These soils are usually moist, and are dry in the moisture control section for less than 45 consecutive days following summer solstice. The mean annual soil temperature ranges from 43 to 46 degrees F. The particle-size control section is 10 to 25 percent volcanic glass and cinders, 35 to 50 percent pebbles, and 10 to 30 percent cobbles by volume. Depth to densic material is 20 to 40 inches. Reaction is strongly acid or moderately acid throughout.
The A horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 2 to 4 moist or dry.
The Bw horizon has value of 3 or 4 moist, 6 or 7 dry, and chroma of 2 through 4 moist or dry. It is very gravelly loam or very gravelly sandy loam.
The BC horizon has value of 3 or 4 moist, 6 or 7 dry, and chroma of 2 through 4 moist or dry, It is very gravelly loam, extremely gravelly sandy loam, extremely gravelly loam, or very gravelly sandy loam.
The C horizon has value of 3 through 5 moist, and chroma of 2 through 4 moist or dry. Some pedons have few to common medium faint bright colored mottles. Dry consistence is hard or very hard. Texture is very gravelly sandy loam, extremely gravelly sandy loam, or very cobbly sandy loam.
COMPETING SERIES: These are the Castile and Farnham series. Both of these soils lack volcanic ash and cinders in the particle-size control section. In addition, Castile soils are stratified sand and gravel in the lower part of the particle-size control section and Farnham soils are 35 to 75 shale fragments in the particle-size control section.
GEOGRAPHIC SETTING: Ohop soils are on terraces and uplands. Slopes range from 0 to 15 percent. Elevation ranges from 1,400 to 2,400 feet. Ohop soils formed in recent volcanic mudflows. Average annual precipitation ranges from 60 to 80 inches. The mean January temperature is about 33 degrees F; and the mean July temperature is about 59 degrees F; and the mean annual air temperature is about 46 degrees F. The frost- free season is 110 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Greenwater, Lemolo, Mowich, Ovall, and Zynbar series. Greenwater soils are sandy. Lemolo soils have an aquic moisture regime. Mowich soils are coarse silty over clayey. Ovall soils have a lithic contact within 40 inches. Zynbar soils are medial.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow runoff; slow permeability. These soils have a perched water table that occurs as high as 1 to 3 feet at times from December through April. They are subject to rare periods of flooding.
USE AND VEGETATION: Used for timber production, watershed and wildlife habitat. Native species are Douglas-fir, western hemlock, and red alder with an understory of vine maple, western swordfern, red huckleberry, salal, longtube northern twinflower, foamflower, evergreen violet, and trailing blackberry.
DISTRIBUTION AND EXTENT: Upper river valleys draining Mount Rainier on the west slopes of the central Cascade mountains, Washington; MLRA 3. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Snoqualmie Pass Area, Pierce County, Washington, 1986.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon
Cambic horizon - from 9 to 30 inches (Bw and BC horizons)
Densic materials - at a depth of 30 inches.
Vitrandic feature - 10 to 25 percent volcanic glass and cinders and an assumed ammonium oxalate aluminum plus one-half iron content of 0.4 to 1.0 percent.
Oxyaquic feature - aquic conditions beginning at 18 inches at some time between December and April.
All depths to diagnostic horizons and features within the range of characteristics are measured from the top of the first mineral horizon.
This soil has been reclassified from a loamy-skeletal, mixed, frigid Aquic Dystrochrepts.