LOCATION DOBBS WAEstablished Series
TAXONOMIC CLASS: Medial-skeletal, ferrihydritic, frigid Oxyaquic Hapludands
TYPICAL PEDON: Dobbs medial loam - in a clear cut burned area on a 49 percent east-facing convex shoulder slope at an elevation of 2,250 feet. (The soil was moist when described. Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
Oe--0 to 3 inches; moderately decomposed leaves, twigs and bark.
Oa--3 to 6 inches; highly decomposed leaves, twigs and bark.
A--6 to 17 inches; dark reddish brown (5YR 3/3) medial loam, brown (7.5YR 5/4) dry; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic and weakly smeary; many very fine, fine, medium and coarse roots; many fine irregular pores; l0 percent rounded and subangular pebbles; moderately acid (pH 6.0); clear wavy boundary. (l0 to l5 inches thick)
Bwl--17 to 27 inches; dark brown (7.5YR 3/4) very gravelly medial loam, yellowish brown (l0YR 5/4) dry; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic and weakly smeary; many very fine, medium and coarse roots; many fine pores; 40 percent rounded and subangular pebbles and a few cobbles; slightly acid (pH 6.2); clear wavy boundary.
Bw2--27 to 38 inches; dark brown (7.5YR 3/4) very gravelly medial loam, yellowish brown (l0YR 5/4) dry; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic and weakly smeary; few fine, medium and coarse roots; common fine and very fine pores; 30 percent pebbles, l5 percent cobbles; slightly acid (pH 6.4); abrupt wavy boundary. (Combined thickness of the Bw horizon is 15 to 30 inches)
2Cd--38 to 66 inches; dark brown (l0YR 4/3) dense glacial till that breaks to extremely gravelly loamy sand, pale brown (l0YR 6/3) dry, massive; extremely hard, extremely firm; 75 percent pebbles and cobbles, few stones; slightly acid (pH 6.4).
TYPE LOCATION: Lewis County, Washington; 2,ll0 feet S. and 3,l70 feet W. of the NE corner of sec. 2l, T. l4 N., R. 3 E., W.M.
RANGE IN CHARACTERISTICS: Average annual soil temperature ranges from 42 to 46 degrees F. Depth to a dense glacial till ranges from 30 to 40 inches. The soil is moderately acid or slightly acid throughout.
The A horizon has hue of 5YR, 7.5YR, or 10YR, value of 2 or 3 moist, 4 or 5 dry; and chroma of 2 or 3 moist and 2 to 4 dry.
The Bw horizon has hue of 7.5YR or l0YR, value of 3 through 5 moist, 4 through 7 dry, and chroma of 4 through 6 moist and dry. It is silt loam, loam, or sandy loam, and has 35 to 40 percent pebbles and 5 to l5 percent cobbles.
The 2Cd horizon is dense glacial till with sandy loam or loamy sand texture, and has 20 to 30 percent rounded cobbles and 40 to 60 percent rounded pebbles. It has hue of 10YR or 2.5Y, value of 4 or 5 moist, 6 or 7 dry, and chroma of 2 through 6 moist and dry.
COMPETING SERIES: These are the Caterl and Laderly series and the similar soils in other families Dougan, Fernwood, Zygore, Jonas, Lates, Murnen, Pheeney, and Vailton series. None of these soils has a paralithic contact with compact glacial till within a depth of 40 inches. Caterl soils are 40 to 60 inches to a lithic contact. Laderly soils are 20 to 40 inches to a lithic contact. In addition, Dougan, Fernwood, Lates, and Pheeney soils have a lithic contact at 20 to 40 inches. Jonas, Murnen, and Vailton soils are deep and medial. Lates soils are medial. Zygore soils are deep.
GEOGRAPHIC SETTING: Dobbs soils are in cirque basins and on adjacent mountain slopes. Slopes range from 5 to 90 percent. Dobbs soils formed in alpine glacial till derived from andesite with a mantle of andesite colluvium, volcanic ash, and pumice. Elevation is 2,000 to 3,200 feet. Average annual precipitation is 70 to ll0 inches. Average January temperature is about 30 degrees F, average July temperature is about 6l degrees F, average annual temperature is 4l to 44 degrees F. The growing season (28 F.) is l60 to l80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Jonas, Pheeney, Reichel,and Stahl soils. Jonas soils are deep. Pheeney soils are 20 to 40 inches deep to a lithic contact. Reichel and Stahl soils are a cryic.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to medium runoff; moderate permeability above the dense glacial till. A perched water table occurs as high as 2.5 to 3.0 feet at times from November through March.
USE AND VEGETATION: Used for timber production, watershed and wildlife habitat. Vegetation is Douglas-fir, western hemlock, western redcedar, Pacific silver fir, and noble fir, with an understory of vine maple, Oregongrape, trailing blackberry, western swordfern, deer fern, Princes pine, pachystima, and salal.
DISTRIBUTION AND EXTENT: Cascade Range in Lewis and Cowlitz Counties, Washington; MLRA 3. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lewis County, Washington, l979.
REMARKS: Diagnostic horizons and feature recognized in this pedon are an umbric epipedon from 6 to 17 inches, a cambic horizon from 17 to 38 inches, and a dense glacial till at 38 inches. The particle-size control section has an estimated moist bulk density of less than 0.90 g/cc, volcanic glass content of 10 to 30 percent, acid-oxalate extractable aluminum plus one-half iron of 1 to 2 percent. The soil is considered to be Oxyaquic.