LOCATION TUNKCREEK WAEstablished Series
TAXONOMIC CLASS: Ashy over sandy or sandy-skeletal, glassy over mixed Xeric Vitricryands
TYPICAL PEDON: Tunkcreek ashy fine sandy loam - on a 27 percent northeast facing slope at 4,440 feet elevation under a mixed coniferous forest canopy. (Colors are for dry soil unless otherwise stated).
Oi--0 to 1.5 inches; slightly decomposed needles, twigs, and mosses; abrupt smooth boundary.
C--1.5 to 2 inches; light gray (10YR 7/1) ashy very fine sandy loam, grayish brown (10YR 5/2) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots; neutral (pH 7.0); abrupt wavy boundary. (0 to 1 inch thick)
Bw1--2 to 8 inches; light yellowish brown (10YR 6/4) ashy fine sandy loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots, few coarse roots; 2 percent pebbles; slightly acid (pH 6.2); clear wavy boundary.
Bw2--8 to 17 inches; light yellowish brown (10YR 6/4) ashy fine sandy loam, yellowish brown (10YR 5/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots, few coarse roots; 5 percent pebbles; slightly acid (pH 6.4); clear wavy boundary. (Combined thickness of the Bw horizon is 13 to 20 inches)
2C1--17 to 32 inches; light gray (10YR 7/2) loamy sand, grayish brown (10YR 5/2) moist; single grain; loose, nonsticky and nonplastic; few fine and medium roots; 10 percent pebbles; slightly acid (pH 6.4); gradual wavy boundary. (15 to 35 inches thick)
2C2--32 to 60 inches; light gray (10YR 7/1) gravelly coarse sand, grayish brown (10YR 5/2) moist, coarse sand grains are multicolored; single grain; loose, nonsticky and nonplastic, few fine and medium roots; 20 percent pebbles; neutral (pH 6.6).
TYPE LOCATION: Colville Indian Reservation; Okanogan County, Washington; about 11 miles northeast of the town of Omak; 100 feet east, 2,350 feet north of the northwest corner of sec. 10, T. 34 N., R. 28 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches ranges from 41 to 43 degrees F. These soils are usually moist but are dry between depths of 12 and 35 inches for 60 to 75 consecutive days following the summer solstice. The volcanic ash mantle is 14 to 20 inches thick. The upper part of the 0 to 40 inch particle-size control section has an estimated moist bulk density of 0.85 to 0.95 g/cc, volcanic glass content of 30 to 60 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of more than 2.0 percent, 15-bar water retention of 5 to 12 percent for air dried samples, and 0 to 15 percent rock fragments. The lower part of the 0 to 40 inch particle-size control section has 0 to 30 percent rock fragments.
The C horizon is absent in some pedons.
The Bw horizon has value of 4 or 5 moist, and chroma of 2 through 4 dry or moist. It is 0 to 10 percent pebbles. Reaction is slightly acid or moderately acid.
The 2C horizon has value of 6 or 7 dry, 4 or 5 moist, and chroma of 1 through 3 dry, 2 or 3 moist. It is loamy sand, sand, or coarse sand and is 0 to 25 percent pebbles and 0 to 5 percent cobbles. Reaction is slightly acid or neutral.
COMPETING SERIES: This is the Resner series. Resner soils are dry for 45 to 60 consecutive days.
GEOGRAPHIC SETTING: Tunkcreek soils are on outwash terraces, mountain toeslopes, and mountain footslopes. Slopes are 0 to 40 percent. These soils formed in glacial outwash, mainly of granitic origin, with a mantle of volcanic ash and loess. Elevations range from 3,500 to 4,600 feet. The climate is characterized by warm, dry summers and cold, moist winters. The average annual precipitation is 22 to 28 inches. The mean January temperature is about 20 degrees F, the mean July temperature is about 60 degrees F, and the mean annual air temperature is 39 to 42 degrees F. The frost-free season is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Buhrig, Manley, Merkel, Resner, Scrabblers, Stapaloop, and Torboy soils. Buhrig soils are loamy-skeletal and moderately deep to bedrock. Manley soils are medial over loamy-skeletal. Merkel soils are frigid and loamy-skeletal. Resner soils are medial over sandy-skeletal. Scrabblers soils are frigid. Stapaloop soils are coarse-loamy and frigid. Torboy soils are frigid and lack a volcanic ash mantle.
DRAINAGE AND PERMEABILITY: Well drained, slow to rapid runoff; moderate permeability above the lithologic discontinuity, very rapid below.
USE AND VEGETATION: Principal uses are timber production, wildlife habitat, and watershed with some livestock grazing. The native overstory vegetation is subalpine fir, Douglas-fir, western larch, lodgepole pine, and Engelmann spruce. The understory consists of pachystima, dwarf huckleberry, longtube twinflower, common princes-pine, pinegrass, kinnikinnick, white spiraea, and Virginia strawberry.
DISTRIBUTION AND EXTENT: Northcentral Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Colville Indian Reservation; Okanogan County, Washington, 1987.
REMARKS: These soils were proposed as the Tunk series 9/85. The name is changed to prevent confusion with the established Trunk series. Diagnostic horizons and features recognized in this soil are an ochric epipedon from 1.5 to 2 inches composed of volcanic ash (Mt. St. Helens 'T' or'W' layer), a cambic horizon from 2 to 17 inches that has andic soil properties and a lithologic break to sandy glacial outwash at 17 inches. The description reflects a change in classification from mixed to glassy over mixed mineralogy.