LOCATION ALEX ID
Established Series
Rev. WJ/RGK/CBR/EED
05/2018
ALEX SERIES
Landscape--alluvial plains
Landform--stream terraces
Slope--0 to 4 percent
Parent material--alluvium derived from rhyolite
Mean annual precipitation--about 600 mm
Mean annual air temperature--about 3 degrees C
Depth class--very deep
Drainage class--somewhat poorly drained
Soil moisture regime--xeric
Soil temperature regime--cryic
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive Aquic Haplocryolls
TYPICAL PEDON: Alex silty clay loam on a 1-percent slope in an area of rangeland at an elevation of 1918 m
A1--0 to 13 cm; silty clay loam, dark gray (10YR 4/1) dry, black (10YR 2/1) moist; moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; 3 percent gravel; slightly alkaline (pH 7.8); clear smooth boundary
A2--13 to 43 cm; silty clay loam, very dark gray (10YR 3/1) dry, black (10YR 2/1) moist; strong fine subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; 2 percent gravel; slightly alkaline (pH 7.8); clear smooth boundary
AB--43 to 58 cm; silty clay loam, pale brown (10YR 6/3) dry, brown (10YR 5/3) moist; strong medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and few fine tubular pores; slightly alkaline (pH 7.8); clear smooth boundary
Bg--58 to 71 cm; sandy clay loam, light gray (10YR 7/2) dry, dark grayish brown (2.5Y 4/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and few fine tubular pores; 1 percent medium prominent iron concentrations, olive brown (2.5Y 4/4) moist; 2 percent gravel; slightly alkaline (pH 7.7); abrupt smooth boundary
2Cg--71 to 84 cm; gravelly sandy clay loam, strong brown (7.5YR 5/6) dry, brown (7.5YR 4/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; common very fine and few fine tubular pores; 1 percent medium prominent iron depletions, dark greenish gray (5G 4/1) moist; 25 percent gravel; slightly alkaline (pH 7.7); clear smooth boundary
3Cg2--84 to 124 cm; extremely gravelly sand, light gray (10YR 7/2) dry, dark yellowish brown (10YR 4/4) moist; single grain; loose; few very fine roots; many fine interstitial pores; 1 percent fine prominent iron depletions, dark greenish gray (5G 4/1) moist; 70 percent gravel; slightly alkaline (pH 7.8); gradual wavy boundary
3Cg3--124 to 150 cm; extremely gravelly sand, light olive gray (5Y 6/2) dry, olive gray (5Y 5/2) moist; single grain; loose; many fine interstitial pores; 85 percent gravel; slightly alkaline (pH 7.8)
TYPE LOCATION: Clark County, Idaho, about 3.7 km southwest of Kilgore, Idaho; about 350 m south and 164 m east of the northwest corner of section 18, T. 12 N., R. 39 E.; Idmon U.S. Geological Survey quadrangle; latitude 44.37201 degrees north, longitude 111.90984 degrees west, datum WGS 84 (coordinates determined with a GPS)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--3 to 6 degrees C
Thickness of mollic epipedon--41 to 64 cm
Depth to redoximorphic features--45 to 76 cm
Depth to sandy-skeletal material--50 to 100 cm
Particle-size control section
Clay content--20 to 34 percent in upper part, 2 to 5 percent in lower part
Total rock fragment content--0 to 30 percent gravel in upper part, 60 to 85 percent gravel in lower part
A horizon
Value--3 to 5 dry, 2 or 3 moist
Chroma--1 to 3 dry or moist
Gravel content--0 to 5 percent
Reaction--7.2 to 7.8 (neutral or slightly alkaline)
Combined thickness--25 to 46 cm
AB horizon
Value--4 to 6 dry, 3 to 5 moist
Chroma--1 to 3 dry or moist
Texture--loam, silt loam, silty clay loam
Gravel content--0 to 5 percent
Reaction--7.2 to 7.8 (neutral or slightly alkaline)
Thickness--15 to 23 cm
Bg horizon
Hue--10YR, 2.5Y
Value--4 to 7 dry, 2 to 4 moist
Chroma--1 to 2 dry or moist
Texture--loam, sandy clay loam
Gravel content--2 to 30 percent
Reaction--7.2 to 7.8 (neutral or slightly alkaline)
Thickness--8 to 41 cm
2Cg horizon
Hue--10YR, 7.5YR, 2.5Y
Value--4 to 7 dry, 2 to 4 moist
Chroma--1 to 6 dry, 1 to 4 moist
Texture--loam, sandy clay loam
Gravel content--2 to 30 percent
Reaction--7.2 to 7.8 (neutral or slightly alkaline)
Thickness--8 to 23 cm
3Cg horizon
Hue--10YR, 2.5Y, 5Y
Value--6 or 7 dry, 4 or 5 moist
Chroma--2 to 4 dry or moist
Texture--loamy sand, sand
Gravel content--60 to 85 percent
Reaction--7.2 to 7.8 (neutral or slightly alkaline)
COMPETING SERIES: None
GEOGRAPHIC SETTING:
Elevation--1800 to 2050 m
Climate--warm summers, cold winters
Mean annual precipitation--405 to 610 mm
Mean annual air temperature--1 to 4 degrees C
Frost-free period--30 to 60 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Fourme--loamy-skeletal family particle-size class; in higher landscape positions
Idmonton--seasonal high water table at a depth of 50 to 100 cm (somewhat poorly drained); in lower landform positions
Kilgore--seasonal high water table at a depth of 50 to 100 cm (poorly drained); in lower landform positions
Longway--argillic horizon; in higher landform positions
Seemore--seasonal high water table at a depth of 50 to 100 cm (poorly drained); in lower landform positions
Sudpeak--more than 35 percent clay in particle-size control section; in similar positions
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained
Depth to endosaturation in normal years--45 to 76 cm in May and June
Saturated hydraulic conductivity (Ksat)--moderately high in upper part, very high in lower part
USE AND VEGETATION:
Major uses--production of hay, wildlife habitat
Potential natural vegetation--Nevada bluegrass, alpine timothy, meadow barley, Baltic rush
DISTRIBUTION AND EXTENT: Lost River Valleys and Mountains of MLRA 12, Eastern Idaho Plateaus of MLRA 13, and Central Rocky Mountains of MLRA 43B in Idaho; small extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clark County, Idaho; 2018
REMARKS:
Diagnostic horizons and features recognized in this pedon
*Mollic epipedon--zone from the surface to a depth of 43 cm
*Aquic conditions--zone below 58 cm
*Particle size control section--zone from 25 to 100 cm
National Cooperative Soil Survey
U.S.A.