LOCATION COWLITZ WAEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Vitrandic Xerorthents
TYPICAL PEDON: Cowlitz extremely gravelly sand on a 2 percent slope at an elevation of 30 feet. (Colors are for moist soil unless otherwise stated.)
C1--0 to 11 inches; dark gray (10YR 4/1) extremely gravelly sand, light gray (10YR 6/1) dry; single grain; loose, nonsticky and nonplastic; 65 percent pebbles, 5 percent cobbles; common very fine and fine roots; neutral (pH 6.8); abrupt smooth boundary. (9 to 12 inches thick)
C2--11 to 24 inches; dark gray (10YR 4/1) very gravelly sand, light gray (10YR 6/1) dry; single grain; loose, nonsticky and nonplastic; 45 percent pebbles, 5 percent cobbles; neutral (pH 6.8) abrupt smooth boundary. (10 to 15 inches thick)
C3--24 to 60 inches; dark gray (10YR 4/1) very gravelly sand, light brownish gray (10YR 6/2) dry; single grain; loose, nonsticky and nonplastic; 45 percent pebbles, 5 percent cobbles; neutral (pH 6.8).
TYPE LOCATION: Cowlitz County, Washington, about 3 miles south of Castle Rock, 2,300 feet west, 2,175 feet north of the southeast corner sec. 26 T. 9 N., R. 2W.
RANGE IN CHARACTERISTICS: These soils are usually moist but are dry in the moisture control section for 60 to 75 consecutive days following summer solstice. The mean annual soil temperature ranges from 51 to 53 degrees F. The particle-size control section averages 35 to 80 percent coarse fragments and 10 to 30 percent volcanic glass. It is slightly acid to neutral.
Some profiles contain woody organic debris.
The C horizons have hue of 10YR or 2.5Y, value of 4 to 6 moist, 6 or 7 dry, and chroma of 0 to 2 moist or dry. Textures are very gravelly sand, extremely gravelly sand, very gravelly loamy sand.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Cowlitz soils are on low river terraces, bottomlands, and terrace escarpments along the Cowlitz and Toutle River at elevations of 10 to 200 feet. Slopes are 0 to 30 percent. Cowlitz soils formed in more than 5 feet of gravelly dredge material over mudflow from the May 18, 1980 eruption of Mt. St. Helens. The climate is characterized by warm, dry summers and cool, moist winters. Average annual precipitation is 45 to 80 inches. The average annual temperature is 49 to 51 degrees F. The growing season (28 degrees F) is 175 to 240 days. The frost-free period is 150 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the proposed Carrolls and Panamaker soils. Carrolls soils are sandy and somewhat poorly drained. Panamaker soils are sandy.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow runoff; rapid permeability. None to occasional flood hazard.
USE AND VEGETATION: Areas have been vegetated with grass seedlings and by red alder and scotch-broom.
DISTRIBUTION AND EXTENT: Cowlitz County, Washington, along the Cowlitz and Toutle Rivers. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Cowlitz County, Washington, 1989.
REMARKS: There are no diagnostic horizons in this pedon. Diagnostics features are a particle-size control section from 10 to 40 inches that is sand throughout and averages 51 percent coarse fragments.