LOCATION BLACKSAN IDEstablished Series
TAXONOMIC CLASS: Sandy, mixed, frigid Entic Haploxerolls
TYPICAL PEDON: Blacksan loamy fine sand - on a south southwest-facing slope of 1 percent under grasses and shrubs at 5,110 feet in rangeland. (Colors are for dry soil unless
otherwise stated. When described on May 20, 1981, the soil was moist throughout.)
A--0 to 10 inches; dark grayish brown (10YR 4/2) loamy fine sand, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable; common very fine and fine roots; few very fine tubular pores; neutral (pH 7.0); clear smooth boundary. (8 to 18 inches thick)
AB--10 to 19 inches; dark grayish brown (10YR 4/2) fine sand, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; soft, very friable; common very fine and fine roots; few very fine tubular pores; 1 percent pebbles; neutral (pH 7.0); gradual smooth boundary. (~0~to 9 inches thick)
Bw--19 to 32 inches; brown (10YR 4/3) fine sand, dark brown (10YR 3/3) moist; massive; soft, very friable; 5 percent pebbles; neutral (pH 7.2); abrupt wavy boundary. (8 to 13 inches thick)
2R--32 inches; vesicular basalt bedrock.
TYPE LOCATION: Fremont County, Idaho; about 5 miles north of St. Anthony; 2,000 feet west and 1,450 feet south of the northeast corner of sec. 12, T.8N., R.40E.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 10 to 18 inches (Mollic colors below this depth are due to dark mineral color.)
Percent clay in the control section - 2 to 8
Average annual soil temperature - 43 to 45 degrees F
Average summer soil temperature - 61 to 63 degrees F
Depth to bedrock - 20 to 40 inches
A horizon
color value, dry - 3 or 4
value, moist - 2 or 3
chroma, dry - 2 through 4
chroma, moist - 2 or 3
reaction - neutral to mildly alkaline
B horizon
Color value, dry - 4 through 6
value, moist - 3 through 5
chroma- 2 through 4 dry or moist
texture - S, FS, LFS
coarse fragments - 0 to 10 percent
reaction - neutral to mildly alkaline
Some pedons do not have an AB horizon between the A and Bw horizons.
COMPETING SERIES: These are the Contact, Engett(T) and the Haypress soils. Contact and Engett soils have bedrock at depths greater than 40 inches. Haypress soils formed in residuum weathered from granitic rocks, and have loamy coarse sand textures; and are moderately to slightly acid throughout.
GEOGRAPHIC SETTING: Blacksan soils are on nearly level to undulating basalt plains at elevations of 4,900 to 5,450 eet. Slopes are 1 to 6 percent. The soils formed in sandy eolian material from mixed sources influenced by slope alluvium. Average annual precipitation is 14 to 18 inches. Average annual temperature is 41 to 43 degrees F. The frost- free period is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Eginbench, Engett(T), Juniperbute (T) Sandcreek (T), and St. Anthony soils. Eginbench soils are very deep, are on lower river terraces and have an induced water table. Engett soils are deep or very deep and are found in concavities. Juniperbute soils are adjacent to sand dunes and lack organic carbon to meet mollic criteria. Sandcreek soils are shallow and are adjacent to rock outcrops on convex positions. St. Anthony soils are on lower river terraces and are moderately deep to sand and gravel.
DRAINAGE AND PERMEABILITY: Excessively drained; runoff is slow; permeability is rapid.
USE AND VEGETATION: The soil is used principally for rangeland with minor areas of soils cropped to irrigated small grains and potatoes. Native vegetation is mainly antelope bitterbrush and needleandthread.
DISTRIBUTION AND EXTENT: These soils are moderately extensive in southeast Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Fremont County, Idaho, 1982
REMARKS: Diagnostic horizons and features recognized in this soil are:
Mollic epipedon - the zone from the surface to approximately 10 inches (A horizon).
Lithic contact - starts at 32 inches (2R horizon).