LOCATION PSUGA WATentative Series
TAXONOMIC CLASS: Medial, amorphic, frigid Typic Haplorthods
TYPICAL PEDON: Psuga loam-forested. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures).
Oe & Oa--1 to 0 inches; decayed needles and twigs, (1 to 4 inches thick).
A--0 to 2 inches; very dark brown (10YR 2/2) loam, dark brown (7.5YR 3/2) dry; weak medium granular structure; soft, friable, nonsticky, nonplastic, weakly smeary; common fine and medium roots. 5 percent rounded gravels; very strongly acid (pH 4.8), abrupt wavy boundary. (1 to 9 inches thick).
Bs1--2 to 5 inches; dark brown (7.5YR 4/4) loam, yellowish brown (10YR 5/4) dry strong medium subangular blocky structure; soft, friable, nonsticky, non- plastic, weakly smeary; common fine and medium roots, 10 percent hard rounded pebbles and 5 percent soft sandstone pebbles; moderately acid (pH 5.6); NaF pH 12.0+; clear smooth boundary. (0 to 4 inches thick)
Bs2--5 to 12 inches; strong brown (7.5YR 4/6) silt loam, strong brown (7.5YR 5/4) dry; moderate medium subangular blocky structure; soft, friable, slightly sticky, nonplastic, weakly smeary; common fine and medium roots; 10 percent hard rounded pebbles, 5 percent soft sandstone pebbles, moderately acid (pH 5.6), pH NaF 12.0+; clear smooth boundary. (7 to 16 inches thick).
BC1--12 to 25 inches; dark yellowish brown (10YR 4/6) gravelly loam, yellowish brown (10YR 5/4) dry; strong medium subangular blocky structure; soft, friable, slightly sticky, nonplastic, weakly smeary; few fine and medium roots; 15 percent hard round pebbles and 10 percent soft sandstone pebbles; moderately acid (pH 5.6); NaF pH 12.0+; clear smooth boundary. (0 to 12 inches thick).
BC2--25 to 35 inches; light olive brown (2.5YR 5/4) gravelly silt loam, yellow (2.5YR 7/4) dry; moderate medium subangular blocky structure; soft, friable, slightly sticky, slightly plastic, weakly smeary; few fine and medium roots; 15 percent hard rounded pebbles and 15 percent soft sandstone pebbles; moderately acid (pH 5.6); NaF pH 11.5 gradual smooth boundary. (0 to 10inches thick).
C--35 to 53 inches light olive brown, (2.5YR 5/4) loamy sand, pale yellow (2.5Y 7/4) and yellowish brown (10YR 5/6) dry, massive, nonsticky, nonplastic; 20 percent soft sandstone pebbles; moderately acid (pH 5.8); NaF pH 10.5, clear smooth boundary. (0 to 20 inches thick).
Cr--53 inches; light olive brown (2.5Y 5/4) soft sandstone that breaks to loamy sand, pale yellow (2.5Y 7/4), dry; massive; can be cut with a spade with difficulty; very hard, very firm; nonsticky, nonplastic; moderately acid (pH 5.8); NaF pH 10.1.
TYPE LOCATION: King County, Washington; southeast sec. 7. T. 23 N., R. 7 E., along road to West Tiger Mountain.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at 20 inches ranges from 42 to 44 degrees F. Depth to a paralithic contact consisting of weathered sandstone ranges from 40 to 60 inches. The particle-size control section averages 0 to 20 percent hard rounded pebbles and 10 to 30 percent soft sandstone pebbles. The upper part of the particle-size control section is weakly smeary to moderate smeary.
The A horizon has hue of 7.5YR or 10YR, value of 2 or 3 moist, 3 to 5 dry, and chroma of 2 to 4 moist. Some undisturbed forested pedons have an E horizon 1 to 2 inches thick.
The Bs horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist, and chroma of 4 to 6 moist or dry. Texture of the lower part is gravelly loam, gravelly silt loam, loam, or silt loam.
The BC horizon has hue of 10YR to 2,5Y; value of 5 to 7 dry, and chroma of 4 to 8 moist or dry. Texture is sandy loam, loam, or gravelly silt loam. The C horizon has hue of 10YR to 2.5Y; value of 6 or 7 dry; and chroma of 4 to 6 moist or dry. Texture is loamy sand, or sandy loam.
COMPETING SERIES: This is the Saxon series. Saxon soils are less than 5 percent rock fragments in the particle-size control section and have grayish mottles in the lower part of the particle-size control section.
GEOGRAPHIC SETTING: Psuga soils are on mountains at elevations from 1,800 to 2,500 feet. Slope ranges from 0 to 65 percent. These soils formed in sandstone and siltstone with an admixture of glacial drift and volcanic ash. Mean annual precipitation ranges from 60 to 90 inches. Mean January temperature is about 34 degrees F; mean July temperature is 56 degrees F; the mean annual temperature is 44 degrees F. The growing season (28 degrees F) is 150 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cathcart, Beausite, Elwell, and the Teneriffe soils. Beausite and Cathcart soils are mesic. Elwell soils are 20 to 40 inches deep to a paralithic to dense glacial till. Teneriffe soils are sandy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained, permeability is moderate; runoff is slow to medium.
USE AND VEGETATION: Used primarily for timber production, watershed, and wildlife habitat. Vegetation is western hemlock, Pacific silver fir, Douglas-fir and red alder with an understory of western swordfern, false azalea, and salmonberry.
DISTRIBUTION AND EXTENT: Foothills on the west slopes of the Central Cascade Mountains in Washington. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Snoqualmie Pass Area Soil Survey, 1982. The name is from Psuga Lake in King County Washington.
REMARKS: This soil was proposed as the Zyzzux Series, in September, 1982. Name was changed to Psuga in November, 1982,