LOCATION SOLO WAEstablished Series
TAXONOMIC CLASS: Mixed, mesic Oxyaquic Udipsamments
TYPICAL PEDON: Solo gravelly loamy sand - under a coniferous forest on a 2 percent southwest-facing slope at an elevation of 1,120 feet. The soil was moist throughout when described. (Colors are for moist soil unless otherwise stated. All textures are apparent field textures).
Oe--2 to 0 inches; loose, partially decomposed organic litter, including needles, leaves, twigs, bark chips, cones and roots; abrupt smooth boundary. (1 to 4 inches thick)
A--0 to 2 inches; very dark gray (10YR 3/1) loamy sand, dark gray (10YR 4/1) dry; very weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many fine and very fine, common medium and few coarse roots; many fine and very fine pores; strongly acid (pH 5.4); clear wavy boundary. (2 to 3 inches thick)
E--2 to 3 inches; very dark grayish brown (10YR 3/2) gravelly loamy sand, light brownish gray (10YR 6/2) dry; very weak medium subangular blocky structure; soft, very friable, nonsticky and plastic; many fine and very fine, common medium and few coarse roots; many fine and very fine pores; 20 percent pebbles; moderately acid (pH 5.8); clear wavy boundary. (1 to 3 inches thick)
Bw1--3 to 9 inches; dark brown (10YR 4/2) gravelly loamy sand, gray (10YR 6/1) and light yellowish brown (10YR 6/4) dry; very weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many fine and very fine common medium and few coarse roots; many fine and very fine pores; 20 percent pebbles; moderately acid (pH 6.0); gradual wavy boundary. (5 to 9 inches thick)
Bw2--9 to 15 inches; dark yellowish brown (10YR 4/4) gravelly loamy sand, light yellowish brown (10YR 6/4) dry; massive; loose nonsticky and nonplastic; common fine and very fine, few medium and coarse roots; many fine and very fine pores; 20 percent pebbles; moderately acid (pH 6.0); abrupt wavy boundary. (5 to 8 inches thick)
Bw3--15 to 20 inches; brown (10YR 5/3) and dark yellowish brown (10YR 4/6) gravelly loamy sand, light gray (10YR 7/2) and very pale brown (10YR 7/4) dry; weak medium and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and very fine and few medium and coarse roots; many fine and very fine pores; 25 percent pebbles, 5 percent pumice; slightly acid (pH 6.2) abrupt wavy boundary. (3 to 6 inches thick)
Bw4--20 to 23 inches; yellowish brown (10YR 5/4) gravelly sand, very pale brown (10YR 7/3); weak medium and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and very fine, and few medium and coarse roots; many fine and very fine pores; 20 percent pebbles, 10 percent pumice; moderately acid (pH 6.0); gradual wavy boundary. (2 to 4 inches thick)
Bw5--23 to 32 inches; brown (10YR 4/3, 5/3) gravelly sand, light gray (10YR 7/2) and very pale brown (10YR 7/3) dry; very weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and very fine, and few medium roots; many fine and very fine pores; 25 percent pebbles; moderately acid (pH 5.8); gradual wavy boundary. (7 to 12 inches thick)
2Cqm--32 to 60 inches; grayish brown (2.5Y 5/2) weakly cemented, extremely gravelly sand, volcanic mudflow, light gray (2.5Y 7/2) dry; massive; very hard, very firm, nonsticky and nonplastic very few very fine, fine and medium roots; many medium pores; 65 percent pebbles, 20 percent cobbles, moderately acid (pH 5.8).
TYPE LOCATION: Cowlitz County, Washington. Approximately 18 miles northeast of Woodland Washington. About 1,500 feet west and 2,500 feet north of the southeast corner, sec. 32, T. 7 N., R 3 E.
RANGE IN CHARACTERISTICS: Average annual soil temperature is 51 to 53 degrees F. Depth to weakly cemented lahar is 20 to 40 inches. These soils are usually moist and are dry for less than 45 consecutive days following summer solstice. The soil is more than 60 percent by weight vitric volcanic ash and pumice from the surfaces to a depth of more than 14 inches.
The particle-size control section is 60 to 80 percent vitric volcanic ash and pumice in the upper 4 to 10 inches and is 30 to 60 percent by weighted average.
The E horizon has value of 2 or 3 moist and 4 dry; and chroma of 1 moist and dry. It is neutral to very strongly acid.
The Bw horizons have value of 4 or 5 moist and 6 or 7 dry; and chroma of 2 to 6 moist and 1 to 4 dry. It is neutral to very strongly acid.
The Bw4 and Bw5 horizons have value of 4 or 5 moist and 7 dry; and chroma of 3 to 6 moist and 2 to 4 dry. It is slightly acid or moderately acid.
The 2Cqm horizon has hues of 2.5Y and 5Y, value of 5 or 6 moist and chroma of 1 or 2 moist or dry. It is weakly cemented lahar or pyroclastic flow that breaks to extremely gravelly sand or extremely cobbly sand with 60 to 85 percent rock fragments.
COMPETING SERIES: These are the Bisbee, Coneward, Dart, Ewall, Panamaker, Preston, and Santaquin series. Bisbee, Dart, Ewall, Preston and Santaquin soils are less than 15 percent volcanic glass in the particle-size control section. Panamaker soils are dry less than 45 consecutive days following the summer solstice. Coneward soils are dry for 125 consecutive days following the summer solstice.
GEOGRAPHIC SETTING: The Solo soils are on terraces and fans at elevations of 400 to 1,600 feet. Slopes are 0 to 8 percent. Solo soils formed in aerially and alluvially deposited volcanic ash and pumice overlying weakly cemented lahar at 20 to 40 inches in depth. The climate is characterized by warm, dry summers and cool moist winters. The average annual precipitation is 70 to 90 inches. The average annual air temperature is 49 to 51 degrees F. The frost-free season is about 165 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mountsolo and Speelyai soils. Mountsolo soils are very shallow and have no Bw horizons. Speelyai spoils are 10 to 20 inches deep to dense lahar.
DRAINAGE AND PERMEABILITY:; Moderately well drained; slow runoff and very rapid permeability to the lahar and slow below. Water is perched at 1.5 to 3 feet for short periods from November through March.
USE AND VEGETATION: Used mainly for timber production, recreation wildlife habitat and watershed. Overstory vegetation consists of Douglas-fir, western hemlock, red alder and bigleaf maple. Understory vegetation consists of vine maple, red huckleberry, western swordfern, cascade Oregon-grape, salal, trailing blackberry, western brackenfern and deer fern.
DISTRIBUTION AND EXTENT: Eastern Cowlitz County, Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Cowlitz County, Washington, 1989.
REMARKS: This soil was mapped as Spellyai variant by the Washington State Department of Natural Resources.
Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the mineral surface to 9 inches and weakly cemented lahar at 32 inches.