LOCATION UNDUSK WA
The Undusk series consists of very deep, well drained soils that formed in residuum and colluvium from basalt with a very thin mantle of volcanic ash. Undusk soils are on backslopes and ridges of mountains and have slopes of 5 to 65 percent. The mean annual precipitation is about 55 inches and the mean annual temperature is about 44 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Humixerepts
TYPICAL PEDON: Undusk gravelly ashy loam - forested (Colors are for moist soils unless otherwise noted. All textures are apparent field textures)
Oi--0 to 1 inch; needles, leaves and twigs.
A1--1 to 7 inches; dark brown (7.5YR 3/3) gravelly ashy loam, brown(7.5YR 5/4) dry; weak fine granular structure; soft, very friable, nonsticky, nonplastic and weakly smeary; common very fine and common fine roots; common fine irregular pores; 20 percent gravel; 5 percent shot like aggregates (2 to 4mm in size); neutral (pH 6.6); clear wavy boundary. (4 to 6 inches thick)
2A2--7 to 16 inches; dark brown (7.5YR 3/3) gravelly loam, strong brown (7.5YR 5/6) dry; weak coarse granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; common fine irregular pores; 20 percent gravel; neutral (pH 6.6); clear wavy boundary. (6 to 9 inches thick)
2Bw1--16 to 25 inches; brown (7.5YR 4/4) very gravelly loam, strong brown (7.5YR 5/6) dry; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and common fine roots; common fine irregular pores; 35 percent gravel; neutral (pH 6.6); clear smooth boundary. (0 to 9 inches thick)
2Bw2--25 to 41 inches; brown (7.5YR 4/4) extremely gravelly loam, light brown (7.5YR 6/4) dry; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and common fine roots; common fine irregular pores; 50 percent gravel, 10 percent cobbles; neutral (pH 6.6); gradual smooth boundary. (14 to 18 inches thick)
2Bw3--41 to 61 inches; brown (7.5YR 4/4) very gravelly loam, reddish yellow (7.5YR 6/6) dry; weak medium subangular blocky structure, slightly hard, friable, slightly sticky and slightly plastic; common very fine and common fine roots; common fine irregular pores; 45 percent gravel, 10 percent cobbles; slightly acid (pH 6.2).
TYPE LOCATION: Skamania County, Washington; about 2 1/2 miles northwest of Underwood; 900 feet south and 500 feet east of the northwest corner of sec. 17, T. 3 N., R. 10E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 45 to 47 degrees F. The surface 4 to 6 inches is dominated by volcanic ash. The umbric epipedon is 10 to 15 inches thick. Rock fragments in the particle-size control section average 35 to 60 percent. The control section has 18 to 25 percent clay. Reaction is slightly acid or neutral. Some pedons have C horizons between 40 and 60 inches.
The A horizon has chroma of 2 or 3 moist. It has 15 to 30 percent gravel and includes 0 to 10 percent shot like aggregates.
The 2Bw horizon has value of 4 or 5 moist, 5 or 6 dry and chroma of 4 to 6 moist and dry. It has 35 to 50 percent pebbles and 0 to 20 percent cobbles and stones. It is very gravelly loam, extremely gravelly loam or very cobbly loam.
COMPETING SERIES: These are the
Snowbrier series. Goodwin and Nanny soils have less than 18 percent clay in the control section. In addition, Nanny soils are very strongly acid to moderately acid in the B horizon. Bearcamp, Brandypeak, Donegan, and Freezeout soils are 20 to 40 inches to bedrock.
GEOGRAPHIC SETTING: Undusk soils are on backslopes and ridges of mountains at elevations of 2,000 to 2,800 feet. Slopes are 5 to 65 percent. These soils formed in residuum and colluvium from basalt with a very thin mantle of volcanic ash. Summers are cool and dry. Winters are cold and wet with snow cover from December through March. The mean annual precipitation is 45 to 65 inches. Mean January temperature is about 23 degrees F, mean July temperature is about 64 degrees F. The mean annual temperature is 42 to 46 degrees F. Frost-free season is 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Chemawa, McElroy, St.
Underwood soils. The Chemawa, St. Martin, and Underwood soils have a mesic temperature regime and are nonskeletal. McElroy soils are mesic and have an ashy mantle 9 to 13 inches thick. Timberhead soils are medial.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability.
USE AND VEGETATION: Used for timber production, wildlife habitat, and grazable woodland. Vegetation is Douglas-fir and grand fir, western hemlock, western redcedar, red alder with an understory of vine maple, common snowberry, common beargrass, and red huckleberry, Oregon-grape, western brackenfern and dwarf rose.
DISTRIBUTION AND EXTENT: Southeastern Skamania County, Washington; MLRA 6. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skamania County, 1981.
REMARKS: Diagnostic horizons and features included in this pedon:
Umbric epipedon - from the mineral soil survey to 16 inches (A1 and A2 horizons)
Cambic horizon - from 16 to 61 inches
Particle-size control section - from 11 to 41 inches
More investigation needed as to xeric or udic soil moisture regime based on vegetation.
National Cooperative Soil Survey