LOCATION GEORGECREEK WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Vitrandic Argixerolls
TYPICAL PEDON: Georgecreek ashy silt loam - on a north facing 17 percent slopes at 2,840 feet elevation, under a mixed ponderosa pine-Douglas-fir canopy. (Colors are for dry soil unless otherwise stated.)
Oi-0 to 2 inches; needles, twigs, leaves, and cones.
A1--2 to 8 inches; grayish brown (10YR 5/2) ashy silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; neutral (pH 7.2); clear wavy boundary.
A2--8 to 13 inches; brown (10YR 5/3) ashy silt loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine, and medium roots; neutral (pH 7.0); clear wavy boundary. (Combined thickness of the A horizon is 8 to 16 inches.)
2BA--13 to 21 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine, fine, and medium roots; neutral (pH 6.8); clear wavy boundary. (0 to 12 inches thick)
2Bt1--21 to 37 inches; light yellowish brown (10YR 6/4) clay loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common faint clay films on ped faces and in pores; few very fine and fine roots; neutral (pH 6.8); clear wavy boundary.
2Bt2--37 to 55 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; slightly hard, firm, slightly sticky and slightly plastic; few faint clay films on ped faces and in pores; few very fine roots; slightly alkaline (pH 7.4); gradual wavy boundary. (Combined thickness of the Bt horizon is 12 to 42 inches.)
2BC--55 to 60 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; 5 percent pebbles, slightly effervescent, slightly alkaline (pH 7.8); abrupt wavy boundary. (0 to 20 inches thick)
Cr--60 inches; highly weathered granodiorite.
TYPE LOCATION: Colville Indian Reservation, Okanogan County, Washington; about 11 miles southeast of the town of Nespelem; 1,800 feet west, 1,100 feet north of the southeast corner of Sec. 1, T. 29 N., R. 31 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches is 48 to 50 degrees F. These soils are usually moist but are dry in all parts between depths of 4 and 12 inches for 75 to 90 consecutive days. Xeric soil moisture regime. The mollic epipedon is 8 to 16 inches thick. The upper 7 to 14 inches has an estimated moist bulk density of 1.15 to 1.30 g/cc, volcanic glass content of 5 to 20 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 0.4 to 1.0 percent, and 15-bar water retention of 5 to 10 percent for air dried samples. Thickness of the solum ranges from 24 to 60 inches. Depth to weathered granitic bedrock ranges from 40 to 60 inches. The particle-size control section averages 18 to 35 percent clay, 25 to 50 percent medium, coarse, and very coarse sand, and 0 to 25 percent rock fragments.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 through 3, dry or moist. The lower part has 0 to 15 percent pebbles. Reaction is slightly acid or neutral throughout.
The BA horizon has hue of 10YR or 2.5Y, value of 5 through 7 dry, 3 through 5 moist, and chroma of 2 through 4, dry or moist. It is silt loam or loam and has 0 to 15 percent pebbles. Reaction is slightly acid or neutral. Some pedons lack a BA horizon and have an E or B/E horizon 6 to 14 inches thick, that has texture and reaction like the BA horizon and hue of 10YR or 2.5Y, value of 5 or 6 dry, 3 through 5 moist, and chroma of 3 through 5, dry or moist.
The Bt horizon has hue of 10YR or 2.5Y, value of 5 through 7 dry, 3 through 5 moist, and chroma of 2 through 6, dry or moist. It is commonly loam, or clay loam, and less commonly sandy clay loam and is gravelly in some pedons. Gravel content is 0 to 25 percent. Reaction is slightly acid, neutral, or mildly alkaline. There are few to common thin clay films on ped faces and lining pores.
The BC horizon has hue of 10YR or 2.5Y, value of 5 through 7 dry, 3 through 5 moist, and chroma of 2 through 6, dry or moist. It is loam or sandy loam and is gravelly in some pedons. It is 5 to 30 percent pebbles and 0 to 2 percent cobbles. Reaction is commonly neutral but ranges to mildly alkaline. Some pedons lack a BC horizon.
Some pedons have a C horizon 6 to 20 inches thick. It has hue of 10YR or 2.5Y, value of 6 or 7 dry, 4 or 5 moist, and chroma of 2 through 4, dry or moist. It is loam or sandy loam and is gravelly in some pedons. It is 5 to 30 percent pebbles and 0 to 3 percent cobbles. Reaction is neutral or mildly alkaline.
COMPETING SERIES: These are the Glenrose, Hillcreek (T), Morical, Mozen (T), Pachneum (T), Ralock (T), Rollinger, Shushuskin (T), Teewee, Tolius, Umperon (T), Vollinger (T), Wenner (T), and Wockum (T) series. Glenrose soils are less than 25 percent medium, coarse, and very coarse sand in the particle-size control section. Hillcreek soils have mollic epipedons 20 to 45 inches thick and are very deep. Morical soils are 20 to 40 inches deep to a paralithic contact. Mozen and Shushuskin soils are 20 to 40 inches deep to a lithic contact. Pachneum, Wenner and Umperon soils are very deep. Ralock soils are very deep and have secondary carbonates at a depth of 22 to 38 inches. Teewee soils have 10 to 25 percent medium, coarse, and very coarse sand and are 40 to 60 inches to weathered andesite bedrock. Tolius soils are very deep. Vollinger soils are very deep and have secondary carbonates at a depth of 43 to 60 inches. Wockum soils are very deep and are dry for 90 to 100 consecutive days.
GEOGRAPHIC SETTING: Georgecreek soils are on broad ridges and mountainsides and formed in residuum from granitic rock with a thin mantle of loess and volcanic ash. Slopes are 3 to 60 percent. Elevations range from 1,800 to 3,400 feet. The climate is characterized by warm, dry summers and cold, moist winters. The average annual precipitation is 15 to 20 inches. The mean January temperature is about 25 degrees F, mean July temperature is about 68 degrees F, and the mean annual air temperature is 45 to 48 degrees F. The frost-free season is 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Dragoon soils and the Bearspring (T), Centralpeak (T), Dinkelman, Ginnis (T), Morical, Skanid, Spokane, Swakane (T), Vanbrunt (T), Whitestone (T), and Yaxon soils. Centralpeak, Dinkelman, Ginnis, and Spokane soils are coarse-loamy. Bearspring, Skanid, Swakane, Vanbrunt, and Whitestone soils are loamy-skeletal. In addition, Centralpeak, Ginnis, Morical, Spokane, and Vanbrunt soils are moderately deep, and Skanid and Swakane soils are shallow. Ginnis, Morical, Swakane, and Yaxon soils are dry for 90 to 105 consecutive days. Bearspring and Centralpeak soils are dry for 60 to 75 consecutive days following the summer solstice.
DRAINAGE AND PERMEABILITY: Well drained, slow to rapid runoff, moderate permeability.
USE AND VEGETATION: Timber production, grazing, wildlife habitat, and watershed are the principal uses. The native vegetation is ponderosa pine, Douglas-fir, pinegrass, common snowberry, white spiraea, heartleaf arnica, Saskatoon serviceberry, and fat false-Solomons-seal. The native vegetation on warm phases consists of ponderosa pine, antelope bitterbrush, Idaho fescue, bluebunch wheatgrass, and arrowleaf balsamroot.
DISTRIBUTION AND EXTENT: North-central Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Colville Indian Reservation, Ferry and Okanogan Counties, Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in this soil are a mollic epipedon from 2 to 13 inches, an argillic horizon from 21 to 55 inches, and a paralithic contact at 60 inches.