LOCATION VANSON WAEstablished Series
TAXONOMIC CLASS: Ashy over medial-skeletal, glassy over amorphic Andic Haplocryods
TYPICAL PEDON: Vanson ashy sandy loam - under a coniferous forest on a 35 percent northeast-facing mountain shoulder slope at an elevation of 3,200 feet. The soil was moist below 1 inch when described. (Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
Oe--0 to 1 inch; loose, partially decomposed organic litter including needles, leaves, twigs, wood, bark chips, and old roots; abrupt smooth boundary. (1 to 4 inches thick)
Oa--1 to 2 inches; decomposed organic matter; abrupt wavy boundary. (1 to 4 inches thick)
E--2 to 3 inches; dark gray (10YR 4/1) ashy loamy sand, light gray (10YR 7/1) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine, medium, and coarse roots; many fine pores; 5 percent subangular pumice fragments (2 to 5mm in diameter); moderately acid (pH 5.6); abrupt irregular boundary. (1/4 to 2 inches thick)
Bs1--3 to 8 inches; dark brown (7.5YR 3/4) ashy sandy loam, brown (7.5YR 5/4) dry; common fine faint strong brown (7.5YR 4/6) mottles, strong brown (7.5YR 4/6) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic, weakly smeary; many fine, medium, and coarse roots; many fine pores; 5 percent subangular pumice fragments (2 to 20mm in diameter); moderately acid (pH 5.8); abrupt wavy boundary. (4 to 8 inches thick)
2Bs2--8 to 14 inches; gray (10YR 5/1) paragravelly ashy loamy sand, light gray (10YR 7/1) dry; many fine prominent strong brown (7.5YR 4/6 and 7.5YR 5/8) mottles, reddish yellow (7.5YR 7/6 and 7.5YR 7/8) dry; massive; slightly hard, very friable, nonsticky and nonplastic; many fine, medium, and coarse roots; many fine pores; 20 percent subangular pumice fragments (2 to 20mm in diameter); 10 percent hard pebbles and shot-like aggregates (2 to 5mm in diameter); slightly acid (pH 6.2); abrupt irregular boundary. (0 to 8 inches thick)
3Bs3--14 to 20 inches; dark yellowish brown (10YR 3/4) shy sandy loam, light yellowish brown (10YR 6/4) dry; moderate medium subangular blocky structure; slightly had, very friable, nonsticky, nonplastic and weakly smeary; many fine, medium, and coarse roots; many fine pores; 5 percent subangular pumice fragments (2 to 20mm in diameter); 10 percent hard pebbles; slightly acid (pH 6.2); abrupt irregular boundary. (4 to 8 inches thick)
4Bs4--20 to 22 inches; strong brown (7.5YR 5/6) and yellowish red (5YR 5/8) very paragravelly ashy loamy sand, reddish yellow (7.5YR 7/6 and 5YR 6/8) dry; single grain; loose; many fine roots; 55 percent subangular pumice fragments (2 to 20mm in diameter); neutral (pH 6.6); abrupt irregular boundary. (0 to 4 inches thick)
5Bw--22 to 41 inches; yellowish brown (10YR 5/4) very gravelly medial loam, very pale brown (10YR 7/4) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; many fine and medium, common coarse roots; many fine pores; 40 percent subangular hard pebbles and 10 percent cobbles; moderately acid (pH 5.6); clear wavy boundary. (10 to 24 inches thick)
5BC--41 to 53 inches; dark yellowish brown (10YR 4/4) very gravelly medial loam, very pale brown (10YR 7/4) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; common fine and medium, few coarse roots; 40 percent subangular hard pebbles and 15 percent cobbles; moderately acid (pH 5.6); abrupt irregular boundary. (8 to 14 inches thick)
5R--53 inches; hard andesite bedrock.
TYPE LOCATION: Cowlitz County, Washington; 2,575 feet south and 1,780 feet east of the northwest corner of sec. 10, T. 7 N., R. 4 E., W.M.
RANGE IN CHARACTERISTICS: Depth to a lithic contact is 40 to 60 inches. Average annual soil temperature at 20 inches ranges from 40 to 42 degrees F. The upper 5 to 20 inches of the control section is estimated to have 30 to 60 percent volcanic ash and pumice and less than 35 percent pumice greater than 2mm. The lower part of the control section averages 35 to 70 percent angular and subangular hard pebbles and cobbles and 30 to 60 percent vitric volcanic ash. Below the E horizon, soil reaction is strongly acid through neutral. Some pedons are 40 to 60 inches deep to a paralithic contact or dense glacial till.
The E horizon has value of 3 through 5 moist, 5 through 8 dry, and chroma of 1 or 2 moist and dry. Soil reaction is moderately acid or strongly acid.
The Bs horizons have hue of 5YR, 7.5YR or 10YR, value of 3 to 6 moist, 5 through 8 dry, and chroma of 1 to 8 moist and dry. Colors are mottled or variegated, especially in horizons containing pumice. It is ashy sandy loam, gravelly ashy loamy sand, or very gravelly ashy loamy sand. Pumice fragments average from 5 to 35 percent. Hard pebbles average from 0 to 15 percent. Shot-like aggregates average from 0 to 10 percent. It has 15-bar moisture (dry) of 10 to 12 percent (estimated).
The 5Bw and 5BC horizons have hue of 5YR through 10YR, value of 4 or 5 moist, 6 or 7 dry, and chroma of 4 through 6 moist and dry. It is medial sandy loam or medial loam. Hard subangular and angular pebbles range from 30 to 55 percent, cobbles from 10 to 30 percent, and stones from 0 to 10 percent. It has 15-bar moisture (dry) of 12 to 15 percent (estimated).
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Vanson soils are on mountain backslopes and ridgetops at elevations of 2,800 to 5,000 feet. Slopes are 5 to 90 percent. These soils formed in residuum and colluvium from volcanic ash and extrusive igneous rock, including andesite, andesitic flow breccia, and olivine basalt, with a mantle of aerially deposited ash and pumice from Mt. St. Helens. The layers of tephra in the pedon are typically distinct. When present, the most easily recognized are the mottled coarse ash and pumice of the 400-year-old layer W and the thin lense of pumice of the 3,500-year-old layer Y. The climate is characterized by cool dry summers and cold wet winters. Average annual precipitation is 80 to 130 inches, including considerable snowfall. The average annual air temperature is 38 to 40 degrees F. Growing season (28 degree F) is 90 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cinnamon, Domell, Hatchet, Hoffstadt, Lonestar, Stahl and Swift soils. Cinnamon, Domell, Hoffstadt, Stahl, and Swift soils lack a spodic horizon. In addition, Cinnamon and Domell soils have less than 35 percent rock fragments in the lower part of the control section and are frigid. Hatchet soils are moderately deep to a lithic contact. Hoffstadt soils are frigid. Lonestar soils hae less than 35 percent rock fragments in the lower part of the control section. Stahl soils have an umbric epipedon and are 20 to 40 inches deep to a lithic contact. Swift soils are frigid.
DRAINAGE AND PERMEABILITY: Well drained, medium to rapid runoff; moderate permeability.
USE AND VEGETATION: Used for timber production, wildlife habitat, watershed, and recreation. Overstory vegetation includes Pacific silver fir, western hemlock, and Douglas-fir. The understory includes vine maple, huckleberry, bunchberry dogwood, common beargrass, princes pine, Oregon-grape, salal, northern twinflower, queenscup beadlily, mosses and lichens.
DISTRIBUTION AND EXTENT: Southwestern Washington on the western slopes of the Cascade Range in eastern Cowlitz and northwestern Skamania Counties. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skamania County, Washington, 1981.
REMARKS: Diagnostic horizons and features recognized in this pedon are an albic horizon from 2 to 3 inches, a spodic horizon from 3 to 8 inches and andic soil properties from 3 to 53 inches. The zone from 8 to 20 inches fails to met the color requirement for a spodic horizon. Field test of NaF pH is less than 9.0 in the E horizon and 12 below the E horizon. The 12 to 42 inch particle-size control section has an estimated moist bulk density of less than 0.90 g/cc, volcanic glass content of 30 to 60 percent, acid-oxalate extractable aluminum plus one-half iron of more than 1 percent.
Classification changed 6/98 by adding mineralogy classes now defined by Soil Taxonomy.
ADDITIONAL DATA: Partial laboratory data available for sample S81WA059-004 in Skamania County, WA; from NSSL 1/30/92.