LOCATION XANA WAEstablished Series
TAXONOMIC CLASS: Ashy-pumiceous, amorphic Typic Vitricryands
TYPICAL PEDON: Xana loamy sand - forested; on a 54 percent slightly convex southeast-facing backslope at an elevation of 3,200 feet. The soil was moist throughout when described. (Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
Oe--3 inches to 0; partially decomposed organic litter including needles, leaves, twigs, bark chips, cones, charcoal and roots; abrupt smooth boundary. (1 to 4 inches thick)
E--0 to 1.5 inches; dark gray (10YR 4/1) loamy sand (volcanic ash), light gray (10YR 7/1) dry; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many fine, medium and coarse roots; many fine irregular pores; moderately acid (pH 5.8); abrupt wavy boundary. (1 to 3 inches thick)
E/Bw1--1.5 to 8 inches; 70 percent dark gray (10YR 4/1) light gray (10YR 7/1) dry; and 30 percent dark brown (7.5YR 3/4), strong brown (7.5YR 5/6 dry; loamy sand (volcanic ash); weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many fine, medium and coarse roots; many very fine and fine irregular pores; 10 percent gravel-sized subangular pumice fragments; moderately acid (pH 6.0); clear wavy boundary.
E/Bw2--8 to 20 inches; 60 percent grayish brown (10YR 5/2), white (10YR 8/1) dry; and 40 percent strong brown (7.5YR 5/6), reddish yellow (7.5YR 7/6) dry; gravelly loamy sand; weak medium and coarse subangular blocky structure; soft, very friable, nonsticky and nonplastic, weakly smeary; many fine, medium and coarse roots; common fine irregular pores; 20 percent gravel-size subangular pumice fragments; moderately acid (pH 6.0); clear wavy boundary. (Combined thickness of the E/B horizon is 14 to 24 inches)
2Bsb1--20 to 32 inches; brown (10YR 4/3) very gravelly sandy loam, very pale brown (10YR 7/3) dry; many very fine and fine prominent yellowish brown (10YR 5/8) mottles, yellow (10YR 7/8) dry; massive; soft, very friable, nonsticky and nonplastic, weakly smeary; many fine and few medium and coarse roots; 50 percent gravel-size pumice fragments of yellowish red (5YR 5/8) and reddish yellow (7.5YR 6/8), reddish yellow (5YR 6/8 and 7.5YR 7/6) dry; neutral (pH 6.6); abrupt wavy boundary. (8 to 14 inches thick)
2Bsb2--32 to 60 inches; yellowish red and reddish yellow (5YR 5/8 and 7.5YR 6/8) extremely gravelly loamy sand, reddish yellow (5YR 6/8 and 7.5 YR 7/6) dry; single grain; loose, nonsticky and nonplastic; common fine and few medium and coarse roots; 70 percent subangular pumice fragments (2mm to 10cm in diameter) and 10 percent gravel-size subangular dark blueish gray or black hard volcanic rock fragments; neutral (ph 6.8).
TYPE LOCATION: Cowlitz County, Washington; near Goat Marsh, about 3,960 feet north and about 1,450 feet east of the southwest corner of section 14, T. 8 N., R. 4 E., W. M.
RANGE IN CHARACTERISTICS: Average annual soil temperature at 20 inches ranges from 38 to 40 degrees F. Depth to the buried profile ranges from 15 to 25 inches. The 0 to 40 inch particle-size control section has an estimated moist bulk density of 0.75 to 0.90 g/cc, volcanic glass content of 60 to 80 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 for air dried samples. The upper part of the 0 to 40 inch control section contains 15 to 30 percent pumice fragments, the lower part of the control section contains greater than 35 percent pumice fragments.
The E horizon has value of 3 through 5 moist, 6 through 8 dry and chroma of 1 or 2 dry and moist.
The E part of the E/Bw horizon has value of 4 or 5 moist, 6 through 8 dry and chroma of 1 through 3 dry and moist. The B part has hue of 7.5YR or 5YR; value of 3 through 5 moist, 5 through 7 dry and chroma of 4 through 8 dry and moist. Gravel-size pumice fragments range from 5 to 30 percent. Reaction is slightly acid or moderately acid.
The 2Bsb1 has value of 4 or 5 moist, 6 through 8 dry and chroma of 2 or 3 dry and moist. Mottles have hue of 10YR through 5YR; value of 4 or 5 moist, 6 through 8 dry and chroma of 4 through 8 dry and moist. Pumice fragments have hue of 7.5YR or 5YR, value of 5 or 6 moist, 6 through 8 dry and chroma of 6 through 8 dry and moist. Texture is sandy loam or loamy sand. Gravel-size pumice fragments range from 35 to 55 percent. Reaction is neutral or slightly acid.
The 2Bsb2 has hue of 7.5YR or 5YR, value of 5 or 6 moist, 6 through 8 dry and chroma of 2 through 8 dry and moist. Texture is loamy sand or sand. Gravel and cobble-size pumice fragments and other volcanic ejecta range from 60 to 90 percent. Reaction is neutral or slightly acid.
COMPETING SERIES: There are no competing series. Similar soils in other families are the Fernow and Goffpeak series. Fernow soils are sandy loam and loam in the upper part and have a spodic horizon formed above the cindery underlying material. Goffpeak soils have a xeric soil moisture regime.
GEOGRAPHIC SETTING: Xana soils are on mountain slopes and ridgetops on the west flanks of Mount St. Helens at elevations of 2,800 to 4,200 feet. Slopes are 5 to 65 percent. These soils formed in layers of aerially deposited dacitic pumice and volcanic ash. Beginning at the surface of the mineral soil, the stratigraphy of pyroclastic material from Mount St. Helens present in Xana profiles is (1) ash and pumice of the 176 year old "layer I", (2) ash and pumice of the pyroclastic flow ash clouds of the 350 year old Kalama eruptive period and the 400 year old "layer W", and (3) pumice of the 3,200 year old "layer Y". The climate is characterized by cool, dry summers and cold, wet winters. Average annual precipitation is 120 to 130 inches which includes considerable snowfall. Average annual air temperature is 37 to 40 degrees F. The growing season (28 degrees F.) is 110 to 125 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hatchet, Polepatch and Shoestring soils. Hatchet soils are medial-skelatal and have a lithic contact at a depth of 20 to 40 inches. Polepatch soils are sandy-skeletal. Shoestring soils are ashy over sandy or sandy-skeletal and have compact lahar material at a depth of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; slow to moderate runoff; moderately rapid permeability to 32 inches and very rapid permeability below this depth.
USE AND VEGETATION: Used mainly for timber production, wildlife habitat, watershed and recreation. Overstory vegetation is Douglas-fir, western hemlock, Pacific silver fir, noble fir, western whitepine. Understory vegetation includes western hemlock, Pacific silver fir, Pacific yew and vine maple. Ground vegetation includes tall blue huckelberry, Oregongrape, common beargrass, western princes pine, salal, bunchberry dogwood, vanillaleaf, longtube twinflower and darkwoods violet.
DISTRIBUTION AND EXTENT: West flanks of Mount St. Helens in the uplands adjacent to Goat Marsh and Goat Mountain in 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: Diagnostic horizons and features recognized in this pedon are an albic horizon from the mineral surface to 1.5 inches that interfingers into a cambic horizon from 1.5 to 20 inches, a buried cambic horizon from 20 to 60 inches and a lithologic break from ashy to cindery at 20 inches. This description reflects a change in classification based on amendment 16.