LOCATION UNDERWOOD WA
The Underwood series consists of very deep, well drained soils formed in residuum and colluvium from basalt and andesite mixed with volcanic ash in the surface. Underwood soils are on back slopes and foot slopes of mountains and benches. Slopes are 2 to 50 percent. The mean annual precipitation is about 50 inches and the mean annual temperature is about 46 degrees F.
TAXONOMIC CLASS: Fine-loamy, isotic, mesic Vitrandic Haploxeralfs
TYPICAL PEDON: Underwood ashy loam - forested, on a 14 percent southeast-facing slope at an elevation of 1,200 feet. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
Oi--0 to 1 inch; slightly decomposed needles, leaves and twigs.
Oa--1 to 2 inches; highly decomposed organic material.
Ac--2 to 10 inches; dark brown (7.5YR 3/2) ashy loam, brown (7.5YR 4/4) dry; weak coarse granular structure; soft, very friable, slightly sticky, nonplastic and weakly smeary; many fine, and common medium roots; many coarse irregular pores; 35 percent fine shot-like aggregates (2 to 4 mm in size); slightly acid (pH 6.2); clear smooth boundary. (7 to 14 inches thick)
2BA--10 to 21 inches; dark brown (7.5YR 3/4) loam, brown (7.5YR 5/4) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common fine and common medium roots; many fine irregular and few fine tubular pores; few gravel; moderately acid (pH 6.0); clear smooth boundary. (0 to 16 inches thick)
2Bt--21 to 37 inches; dark brown (7.5YR 3/4) clay loam, brown (7.5YR 5/4) dry; moderate medium subangular blocky structure; hard, friable, slightly sticky and moderately plastic; few fine, few medium, and few coarse roots; many fine irregular and few fine tubular pores; 5 percent paragravel; common distinct clay films in pores and on faces of peds; strongly acid (pH 5.4); clear wavy boundary. (16 to 46 inches)
2C--37 to 62 inches; dark yellowish brown (10YR 4/6) paragravelly loam, brownish yellow (10YR 6/6) dry; common medium distinct mottles of yellowish red (5YR 4/6) moist and dry; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; common medium irregular and common medium tubular pores; 15 percent paragravel; very strongly acid (pH 5.1)
TYPE LOCATION: Skamania County, Washington; about l mile south of Willard; 200 feet south and l,700 feet west of the northeast corner of section 11, T. 3 N., R. 9 E. (Latitude 45 degrees 45 minutes 55 seconds N. and Longitude 121 degrees 38 minutes 08 seconds W.)
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 50 degrees F. The soil moisture control section is dry in all parts for 45 to 60 consecutive days within the 4 months that follow the summer solstice in 6 or more years out of 10. Solum thickness is 30 to 40 inches. Depth to bedrock is 60 inches or more. Volcanic ash influence is 7 to 14 inches thick and has an estimated moist bulk density of 1.10 to 1.30 g/cc, volcanic glass content of 5 to 30 percent, acid oxalate extractable aluminum plus one-half iron of 1.0 to 2.0 percent, phosphate retention of 50 to 75 percent, and 15 bar water retention of 8 to 12 percent and has l5 to 35 percent shot-like aggregates. The particle-size control section ranges from 25 to 35 percent clay. The particle-size control section averages 5 to 30 percent pararock fragments and 0 to 20 percent gravel and cobbles. Below the particle-size control section rock fragments range from 0 to 25 percent and parafragments from 0 to 50 percent.
The Ac horizon has hue of 5YR or 7.5YR, value of 3, 4 or 5 dry, 3 or 4 moist and chroma of 2 to 4 moist, 3 to 6 dry. Texture is . Reaction is slightly acid or neutral. Some pedons have an ABc horizon with color and texture similar to the Ac horizon.
The 2Bt horizon has hue of 5YR or 7.5YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 4 to 6 dry. Texture is loam, gravelly loam, paragravelly loam, or clay loam. Reaction is strongly acid to slightly acid.
The C horizon, when present, has hue of 5YR, 7.5YR or 10YR, value of 4 or 5 moist, 5 or 6 dry and chroma of 4 to 6 dry. Texture is loam, gravelly loam, clay loam, paragravelly loam, or very paragravelly loam. Reaction is strongly acid or moderately acid.
COMPETING SERIES: These are the
Wilkeson series. The
Mcgowan series have a similar classification except for mixed mineralogy and superactive CEC activity class.
Bernhill soils dry for 60 to 90 consecutive days following the summer solstice; lack parafragments
Kramerhill soils 40 to 60 inches to a paralithic contact (gneiss); dry for 60 to 90 consecutive days following the summer solstice
Ulhalf soils 40 to 60 inches to a paralithic contact (andesite); dry for 105 consecutive days following the summer solstice
Wilkeson soils 60 inches or more to the base of the argillic horizon; lack parafragments; hue in argillic horizon of 2.5Y to 7.5YR
Kephart soils mixed mineralogy; dry for 90 to 130 consecutive days following the summer solstice; lack pararock fragments
McGowan soils mixed mineralogy; 60 inches or more to the base of the argillic horizon; lack parafragments in the particle-size control section
GEOGRAPHIC SETTING: Underwood soils are on backslopes and footslopes of mountains, benches, and plateaus at elevations of 400 to 2,800 feet. Slopes are 2 to 50 percent. The soil formed in residuum and colluvium from basalt and andesite mixed with volcanic ash in the surface. The climate is characterized by warm and dry summers and cold and wet winters with intermittent snow cover. The mean annual precipitation is 35 to 65 inches. The mean January temperature is about 27 degrees F. and the mean July temperature is about 66 degrees F. The mean annual temperature is 45 to 48 degrees F. The frost-free season is 100 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Undusk soils on nearby upland and mountain landscapes. Chemawa and Timberhead soils are ashy. McElroy and Undusk soils are skeletal. Also, Timberhead and Undusk soils are frigid.
DRAINAGE AND PERMEABILITY: Well drained, medium to rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for timber production, some orchards and homesites, wildlife habitat, and livestock grazing. Native vegetation is Douglas-fir, bigleaf maple, vine maple, salal, starflower, and western brackenfern.
DISTRIBUTION AND EXTENT: Southeastern Skamania County and western Klickitat County, Washington. MLRA 6. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skamania County, Washington, l947.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 2 to 21 inches
Argillic horizon - the zone from 21 to 37 inches
Vitrandic subgroup feature - the zone from 2 to 10 inches
Particle-size control section - the zone from 21 to 37 inches
Depths to diagnostic horizons and features are measured from the top of the first mineral layer.
National Cooperative Soil Survey