LOCATION THORNOCK IDEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, mesic Lithic Xeric Haplocalcids
TYPICAL PEDON: Thornock stony loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 3 inches; brown (10YR 5/3) (pale brown 10YR 6/3, crushed) stony loam, dark grayish brown (10YR 4/2) moist; weak thin platy structure parting to weak very fine granular; soft, very friable, slightly sticky and slightly plastic; common fine and medium roots; common very fine tubular pores; 10 percent gravel, 5 percent cobbles, and 5 percent stones; neutral (pH 7.2); gradual smooth boundary. (1 to 4 inches thick)
A2--3 to 6 inches thick; pale brown (10YR 6/3) stony loam, dark brown (10YR 4/3) moist; weak very fine granular structure; slightly hard, very friable, slightly sticky, slightly plastic; common fine and medium roots; common very fine and fine tubular pores; 5 percent gravel; 10 percent cobbles, and 10 percent stones; slightly effervescent; slightly alkaline (pH 7.4); clear wavy boundary. (0 to 8 inches thick)
Bk--6 to 15 inches; very pale brown (10YR 7/3) stony loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; common fine and medium roots; common very fine and fine tubular pores; 10 percent gravel, 5 percent cobbles, and 15 percent stones; strongly effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (6 to 16 inches thick)
2R--15 inches; black (10YR 2/1) basalt; vesicular; thick coating of calcium carbonate on surface and in cracks and pores of rock; some vesicles contain light reddish brown (5YR 6/4) or pale brown material.
TYPE LOCATION: Bingham County, Idaho; about 7 miles north and 5 miles west of Aberdeen on an undulating basalt plain; 200 feet south and 100 feet west of the northeast corner of section 27, T. 4 S., R. 30 E.
RANGE IN CHARACTERISTICS:
Depth to calcic horizon - 6 to 12 inches
Depth to bedrock - 10 to 20 inches
Average annual soil temperature - 47 to 58 degrees F.
Particle-size control section
Total clay content - 8 to 18 percent
Carbonate free clay - 5 to 10 percent
Rock fragments - average 5 to 35 percent
A horizon
Value - 5 or 6 dry, 3 or 4 moist
Chroma, dry or moist - 2 or 3
Reaction - neutral to moderately alkaline
Bk horizon
Value - 6 through 8 dry, 4 through 6 moist
Chroma, dry or moist - 2 or 3
Texture - SIL, FSL, CB-L, ST-L, or CBV-L
Effervescence - strong or violent
Calcium carbonate equivalent - 15 to 25 percent
Reaction - slightly or moderately alkaline
COMPETING SERIES: There are no competing series in this family. Similar soils are the Portino and Trevino series. Portino soils have basalt bedrock at a depth of 20 to 40 inches. Trevino soils lack calcic horizons.
GEOGRAPHIC SETTING: Thornock soils are on loess-mantled basalt plains. Slopes range from 0 to 12 percent. They formed in loess and silty alluvium derived from loess and material weathered from basalt. Average annual precipitation ranges from 8 to 12 inches. Average annual air temperature ranges from 46 to 56 degrees F. Frost-free season is about 100 to 140 days. Elevation ranges from 3,000 to 4,800 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kimama and Portneuf soils and the competing Portino and Trevino soils. Kimama soils are fine-silty, have argillic horizons, and are greater than 60 inches deep. Portneuf soils are coarse-silty and are greater than 60 inches deep. Kimama soils are in depressional areas on basalt plains. Portneuf and Portino soils are in areas on basalt plains where the deposits overlying the basalt are thicker. Trevino soils are on basalt plains in areas of thinner loess deposits over the bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderate permeability.
USE AND VEGETATION: Used primarily as rangeland. Small areas are used for irrigated cropland. The potential natural vegetation is mainly bluebunch wheatgrass, Sandberg bluegrass, Thurber needlegrass, and Wyoming big sagebrush.
DISTRIBUTION AND EXTENT: Moderately extensive in the basalt plains of southern Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Bingham County, Idaho, 1972.
REMARKS: Thornock soils were previously classified as Lithic Xerollic Calciorthids. Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to 6 inches (A1 and A2 horizons)
Calcic horizon - the zone from 6 to 15 inches (Bk horizon)
Lithic contact - the contact with basalt at 15 inches (2R)
Particle-size control section - the zone from 10 to 15 inches (part of the Bk horizon). In some pedons it encompasses the entire soil.