LOCATION SINNICE WAEstablished Series
TAXONOMIC CLASS: Ashy over pumiceous or cindery, glassy Thaptic Vitricryands
TYPICAL PEDON: Sinnice extremely paragravelly loamy sand - forested on a 65 percent southwest facing slope at 2,910 feet. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
Oi--1/4 inch to 0; leaves, twigs, and needles.
A--0 to 1 inch; very dark grayish brown (10YR 3/2) paragravelly very fine sandy loam (volcanic ash and pumice), gray (10YR 6/1) dry; single grain; soft, very friable, nonsticky and nonplastic; many very fine roots; few fine irregular and tubular pores; 30 percent pumice fragments; slightly acid (pH 6.4); clear smooth boundary. (2 to 6 inches thick)
BE--1 to 7 inches; light gray (10YR 7/1) extremely paragravelly loamy sand (pumice and volcanic ash), white (10YR 8/1) dry; common, fine distinct stains of brownish yellow (10YR 6/8) and yellow (10YR 7/8) dry; single grain; loose, nonsticky and nonplastic; many very fine and few medium roots; many medium and coarse irregular pores; 70 percent pumice fragments and 10 percent pebbles; slightly acid (pH 6.4); abrupt smooth boundary. (4 to 11 inches thick)
2Bw1--7 to 9 inches; dark brown (10YR 3/3) fine sandy loam (volcanic ash), light gray (10Y 7/2) dry; weak very fine granular structures; soft, very friable, nonsticky and nonplastic; many very fine and common medium roots; common fine irregular pores; slightly acid (pH 6.2) abrupt smooth boundary. (2 to 4 inches thick)
2Bw2--9 to 15 inches; very dark brown (10YR 2/2) loamy sandy (volcanic ash), very dark grayish brown (10YR 3/2) dry; single grain; soft, very friable, nonsticky and nonplastic; many very fine, common medium, and few coarse roots; common fine irregular pores; slightly acid (pH 6.4); abrupt smooth boundary. (6 to 15 inches thick)
3C--15 to 60 inches; light gray (10YR 7/1) extremely paragravelly sand (pumice and volcanic ash), white (10YR 8/1) dry; many, fine and medium distinct stains of brownish yellow (10YR 6/8) and yellow (10YR 7/8) dry; single grain; loose; common fine and few coarse roots; many medium and coarse irregular pores; 75 percent pumice and 15 percent pebbles (2 to 10 mm in size); slightly acid (pH 6.4).
TYPE LOCATION: Skamania County, Washington on Forest Service Road N92H; about 1,250 feet south and 1,100 feet west of the northeast corner of sec. 19, T. 9 N., R. 6 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 38 to 43 degrees F and the mean summer soil temperature is less than 47 degrees F. The soils are dry for less than 45 consecutive days after the summer solstice. All pumice fragments are very weakly to moderately cemented (para). The soil profile has over 60 percent glass throughout all horizons. The 15-bar water content on air-dry samples is 3 to 10 percent throughout all horizons. Depth to the 2Bw is 8 to 17 inches. Depth to the base of the 2Bw is 14 to 36 inches. The A and BE horizons have phosphate retention of 25 to 35 and acid oxalate aluminum plus one-half the iron of 0.4 to 1.0. The 2Bw horizons have phosphate retention of 35 to 50 and acid oxalate aluminum plus one-half the iron of 0.4 to 1.0. The particle-size control section is ashy-pumiceous over ashy over pumiceous with the contrasting parts typically being the ashy (2Bw) and the pumicenous (3C) but some pedons may quality as ashy-pumiceous over ashy.
The A horizon has value of 2 or 3 moist, 5 or 6 dry, and chroma of 1 or 2 moist and dry.
The BE horizon has stains with a hue of 10YR or 7.5YR, value of 5 through 7 moist, 6 through 8 dry, and chroma of 3 through 8 moist and dry.
The 2Bw horizon has value of 2 or 3 moist, 3 through 7 dry, and chroma of 1 through 4 moist and dry. Only the upper 2 to 4 inches may lack mollic colors. It is stratified fine sandy loam, sandy loam, and loamy sand. Pumice fragments range from 0 to 15 percent. It is 8 to 19 inches thick and averages 3 to 5 percent organic carbon.
The 3C horizon has 65 to 80 percent pumice and 5 to 15 percent pebbles. Stains have hue 10YR or 7.5YR, value of 5 through 7 moist, 6 through 8 dry, and chroma of 3 through 8 moist and dry.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Sinnice soils are on backslopes and ridgetops of mountains at elevations of 2,800 to 5,000 feet. Slopes are 5 to 90 percent. Sinnice soils formed in layers of aerially deposited volcanic ash and pumice. Beginning at the surface of the mineral soil, the stratigraphy of pyroclastic material from Mt. St. Helens in Sinnice soil profiles is (1) fresh ash and pumice of the 176-year-old "Layer T", (2) ash of the 400-year-old "Layer X", and (3) pumice of the 400-year- old "Layer W". Some pedons now have a deposit of 1980 St. Helens ash and pumice. The climate is characterized by cool, moist summers and cold, wet winters. Mean annual precipitation is 115 to 135 inches. Average January temperature is 24 degrees F., the average July temperature is 58 degrees F., and the mean annual temperature is 38 to 41 degrees F. The frost-free season is 75 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Colter, Minniepeak and Pelee series. Colter soils are ashy-pumiceous.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Used for timber production, recreation, wildlife habitat, and watershed. Overstory vegetation includes Douglas-fir, western hemlock, and Pacific silver fir; ground cover includes western brackenfern, red huckleberry, vine maple, princess pine, Sitka alder, and willow.
DISTRIBUTION AND EXTENT: Skamania County, Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skamania County, Washington, 1981.
REMARKS: Diagnostic horizons and other features.
Andic soil properties from the mineral surface to 60 inches
Ochric epipedon
Buried umbric epipedon from 7 to 15 inches (Thaptic)
Particle-size control section - 0 to 7 inches ashy-pumiceous, 7 to 15 inches ashy, 15 to 40 inches pumiceous.
Classification changed 6/98 to reflect mineralogy revisions in Soil Taxonomy.
ADDITIONAL DATA: NSSL data from satellite location S81WA-059-002 Sample numbers 81P 3195-3204.