LOCATION SITDOWN WAEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, isotic Haploxerandic Haplocryepts
TYPICAL PEDON: Sitdown gravelly ashy loam - on a northwest-facing 44 percent slope, at an elevation of 3,820 feet under a mixed conifer canopy. (Colors are for dry soil unless otherwise stated).
Oi--0 to 1 inch; slightly decomposed needles, twigs, and cones.
Oe--1 to 2 inches; moderately decomposed forest litter.
A--2 to 4 inches; brown (10YR 5/3) gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, fine and medium roots, few coarse roots; 20 percent rounded gravel; slightly acid (pH 6.2); clear wavy boundary. (1 to 3 inches thick)
Bw--4 to 13 inches; pale brown (10YR 6/3) gravelly ashy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, and medium roots; few coarse roots; 20 percent rounded gravel; slightly acid (pH 6.2); abrupt wavy boundary. (8 to 13 inches thick)
2C1--13 to 29 inches; pale brown (10YR 6/3) very gravelly loamy sand, brown (10YR 4/3) moist; single grain; loose, nonsticky and nonplastic; common very fine and fine roots, few medium roots; 35 percent rounded gravel, 15 percent cobbles; neutral (pH 6.8); clear wavy boundary. (13 to 21 inches thick)
2C2--29 to 60 inches; light brownish gray (10YR 6/2) very gravelly sand, dark grayish brown (10YR 4/2) moist; single grain; loose, nonsticky and nonplastic; few very fine and fine roots; 35 percent rounded gravel, 15 percent cobbles; neutral (pH 6.8).
TYPE LOCATION: Colville Indian Reservation; Okanogan County, Washington; about 16 miles north of the town of Nespelem; 1,200 feet south and 2,200 feet east of the northwest corner sec. 2, T. 33 N., R. 31 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 39 to 43 degrees F. These soils are usually moist but are dry in all parts between a depth of 12 and 35 inches for 45 to 60 consecutive days following the summer solstice. The volcanic ash mantle is 10 to 14 inches thick and has an estimated moist bulk density of 0.75 to 1.00 g/cc, volcanic glass content of 30 to 60 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 1.0 to 2.0 percent, and 15-bar water retention of 5 to 12 percent for air dried samples. The particle-size control section averages 35 to 65 percent rock fragments.
The A horizon has value of 5 or 6 dry, 3 to 5 moist, and chroma of 2 to 4 dry or moist. It is moderately acid to neutral.
The Bw horizon has value of 5 or 6 dry, 4 or 5 moist, and chroma of 3 or 4 moist, 3 to 6 dry. It is 10 to 30 percent gravel, 0 to 5 percent cobbles, and 0 to 15 percent stones. It is gravelly ashy loam, gravelly ashy sandy loam or stony ashy sandy loam. It is slightly acid or neutral.
The 2C horizon has hue of 10YR or 2.5Y, value of 6 or 7 dry, 4 through 6 moist, and chroma of 1 through 3 dry or moist. It is very gravelly or extremely gravelly loamy sand, very cobbly loamy sand, very gravelly sand or very cobbly sand with 20 to 65 percent gravel, 5 to 20 percent cobbles, and 0 to 20 percent stones. It is slightly acid or neutral.
COMPETING SERIES: These are the Bromas and Littlesalmon series. Bromas soils are 20 to 40 inches to bedrock. Littlesalmon soils have a udic soil moisture regime.
GEOGRAPHIC SETTING: Sitdown soils are on backslopes and footslopes of mountains, outwash terraces and terrace escarpments. Elevations range from 2,800 to 6,500 feet. These soils formed in glacial outwash and ablation till with a mantle of volcanic ash and loess. Slopes are 0 to 70 percent. The climate is characterized by cold, wet winters and cool, dry summers. The average annual precipitation ranges from 20 to 35 inches. The mean January temperature is about 20 degrees F, mean July temperature is about 60 degrees F, and the mean annual air temperature is 35 to 41 degrees F. The frost-free season is 60 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Manley, Moses, Nevine, Oxerine, Parmenter, Resner, Sacheen, Togo, and Torboy soils. Manley, Resner, and Togo soils have a volcanic ash mantle greater than 14 inches thick. In addition, Manley and Togo soils are loamy-skeletal in the lower part of the control section. Manley soils are on the upper slopes of foothills and mountains. Togo series are on backslopes, footslopes and ridges of mountains. Nevine, Oxerine, Parmenter, Sacheen, and Torboy soils have a frigid temperature regime. Nevine soils are on moraines, foothills and mountains. Oxerine soils are on footslopes, backslopes, shoulders and ridges of hills and mountains. Parmenter soils are on kames, kame terraces and outwash terraces. Resner, Torboy and Sacheen soils are on similar landscapes as Sitdown soils. Moses soils are 20 to 40 inches deep to a paralithic contact and are on toeslopes, footslopes, backslopes and broad ridges of mountains.
DRAINAGE AND PERMEABILITY: Well drained, medium to very rapid runoff; moderate permeability in the A and Bw horizons and very rapid in the 2C horizon.
USE AND VEGETATION: Timber production, wildlife habitat, watershed, grazing and recreation are the principal uses. Native vegetation includes western larch, Douglas-fir, subalpine fir, lodgepole pine, blackmountain huckleberry, pachystima, queencup beadlily, longtube twinflower, sidebells shinleaf, western rattlesnake plantain, and pinegrass.
DISTRIBUTION AND EXTENT: Northeastern Washington. MLRA 43A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Colville Indian Reservation, Ferry County, Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in this soil are an ochric epipedon from 0 to 7 inches, a cambic horizon from 4 to 13 inches formed in volcanic ash, and an average of 49 percent rock fragment in the particle-size control section from 12 to 42 inches. Further investigation is needed as to a udic soil moisture regime.
The 3/2008 description reflects a change in classification from Sandy-skeletal, isotic Andic Eutrocryepts to Sandy-skeletal, isotic Haploxerandic Haplocryepts due to revision of the cryepts great groups and subgroups. The competing series section was not updated and should be reviewed after all the cryepts have been re-classified.