LOCATION ALEXANDER ID
Tentative Series
Rev. CJH-KLM-BAG-RJS
07/2017
ALEXANDER SERIES
Landform--valley floors, mountain slopes, fan remnants, hillslopes
Slope--2 to 20 percent
Parent material--loess over basalt
Mean annual precipitation--about 450 mm
Mean annual air temperature--about 3.0 degrees C
Depth class--moderately deep
Drainage class--well drained
Soil moisture regime--xeric
Soil temperature regime--frigid
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Argixerolls
TYPICAL PEDON: Alexander silt loam on a northeast rangeland slope of 4 percent and an elevation of 1945 m (The soil was dry when described on August 5, 2008.)
A1--0 to 5 cm; silt loam, dark brown (10YR 3/3) dry, very dark brown (10YR 2/2) moist; weak thick platy structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, and common medium roots; many very fine and fine, and few medium tubular and irregular pores; 5 percent gravel; slightly alkaline (pH 7.6); abrupt smooth boundary
A2--5 to 33 cm; silt loam, brown (10YR 4/3) dry, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine, common fine and medium, and few coarse roots; many very fine and fine, and few medium tubular pores; 10 percent gravel; neutral (pH 7.2); clear wavy boundary
Bt--33 to 71 cm; silty clay loam, dark yellowish brown (10YR 4/4) dry, dark yellowish brown (10YR 3/4) moist; strong fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and few fine roots; few very fine and fine tubular pores; 15 percent distinct clay films on ped faces and 10 percent distinct clay films on rock fragments; 10 percent gravel; neutral (pH 7.2); abrupt wavy boundary
R--71 cm; basalt bedrock
TYPE LOCATION: Caribou County, Idaho; east of the Blackfoot Reservoir and about 5.4 kilometers southeast of the junction between the Bone Road and Government Dam Road; 740 meters south and 400 meters west of the northeast corner of section 9, T. 5 S., R. 41 E.; Henry, U.S. Geological Survey topographic quadrangle; latitude 42.9993 degrees north, longitude 111.6534 degrees west, datum WGS 84 (coordinates determined by GPS)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--3.0 to 6.0 degrees C
Mean summer soil temperature--15.0 to 18.0 degrees C
Mollic epipedon thickness--25 to 48 cm
Argillic horizon thickness--20 to 40 cm
Depth to bedrock--50 to 100 cm
Particle-size control section averages
*24 to 32 percent clay
*5 to 30 percent gravel
A1, A2 horizons
Value--3 to 5 dry, 2 or 3 moist
Chroma--2 or 3 dry or moist
Clay content--15 to 27 percent
Rock fragment content--0 to 15 percent gravel
Reaction--pH 6.6 to 7.8
Thickness (A1, A2 combined)--23 to 48 cm
Bt horizon
Hue--10YR or 7.5YR dry or moist
Value--4 to 6, dry, 3 to 5 moist
Chroma--2 to 4 dry or moist
Texture (less than 2 mm)--silty clay loam, clay loam
Rock fragment content--5 to 30 percent gravel
Clay content--20 to 35 percent
Reaction--pH 6.6 to 7.3
Thickness--20 to 64 cm
COMPETING SERIES:
Ayoub--has a C horizon with greater than 35 percent rock fragments
Cloud Rim--are very deep
Cloudless--are very deep
Dry Canyon--are deep to a paralithic contact
Isbell--are deep or very deep
Jacanyon--has channers in the BC horizon
Kanlee--has a paralithic contact above a lithic contact
Maple Mountain--has cobbles throughout
Paynecreek--are deep and very deep
Ticino--moderately deep to a paralithic contact
GEOGRAPHIC SETTING:
Elevation--1,800 to 2,080 meters
Climate--warm summers, cold winters
Mean annual precipitation--400 to 500 mm
Mean annual air temperature--2.0 to 4.5 degrees C
Frost free period--60 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturated hydraulic conductivity (Ksat)--moderately high
USE AND VEGETATION:
Major uses--livestock grazing and wildlife habitat
Vegetation--mountain big sagebrush, antelope bitterbrush, bluebunch wheatgrass, and Nevada bluegrass
DISTRIBUTION AND EXTENT: Eastern Idaho Plateaus, Idaho; MLRA 13; small extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Caribou County, Idaho; Caribou County Area Idaho Soil Survey; January, 1981
REMARKS:
Diagnostic horizons and other features in this pedon are:
Mollic epipedon--zone from 0 to 33 cm (A1, A2 horizons);
Argillic horizon--zone from 33 to 71 cm (Bt horizon);
Lithic contact--71 cm (R horizon); and
Particle-size control section--zone from 33 to 71 cm (Bt horizon).
Note: Type location moved from previous location on 5/25/2017 to more representative location.
National Cooperative Soil Survey
U.S.A.