LOCATION TARNACH UT+NVEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, active, mesic Lithic Xeric Haplocalcids
TYPICAL PEDON: Tarnach very gravelly loam--rangeland. (Colors are for the dry soil unless otherwise noted.)
A--0 to 10 cm; pale brown (10YR 6/3) very gravelly loam, brown (10YR 5/3) moist; weak thin platy structure parting to weak fine granular; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine, and few medium roots; few very fine vesicular pores; slightly effervescent; carbonates are disseminated; 50 percent gravel; strongly alkaline (pH 8.6); abrupt smooth boundary. (5 to 13 cm thick)
Bk1--10 to 23 cm; pale brown (10YR 6/3) very gravelly loam, brown (10YR 5/3) moist; weak fine subangular blocky structure parting to weak fine granular; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine, and few medium roots; few very fine tubular pores; slightly effervescent; carbonates are disseminated and in prominent masses around rock fragments; 40 percent gravel; strongly alkaline (pH 8.8); clear smooth boundary.
Bk2--23 to 38 cm; pale brown (10YR 6/3) very gravelly loam, brown (10YR 5/3) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; few very fine tubular pores; strongly effervescent; carbonates are disseminated and in prominent masses around rock fragments; 45 percent gravel; strongly alkaline (pH 9.0); clear smooth boundary. (Combined thickness of the Bk horizons is 18 to 43 cm)
R--38 cm; slightly fractured limestone bedrock.
TYPE LOCATION: Box Elder County, Utah; about 1.5 miles southwest of Trail Pass Reservoir; 2,000 feet east and 1,800 feet north of the southwest corner of section 29, T. 11 N., R. l3 W.; Russian Knoll USGS quad; latitude 41 degrees 38 minutes 51.0 seconds N and longitude 113 degrees 21 minutes 37.3 seconds W; NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry; moist in winter and spring and for brief periods in late summer due to convection storms; aridic bordering on xeric soil moisture regime.
Mean annual soil temperature: 8 to 12 degrees C.
Depth to bedrock: 25 to 50 cm.
Depth to calcic horizon: 5 to 28 cm.
Some pedons contain up to 5 percent durinodes.
Particle-size control section - Clay: 18 to 27 percent.
Rock fragments: 35 to 65 percent; mainly gravel or channers.
A horizon
Value: 5 through 7 dry and 4 or 5 moist.
Chroma: 2 or 3.
Effervescence: Slightly effervescent or strongly effervescent.
Reaction: Moderately alkaline or strongly alkaline.
Consistence: Soft to slightly hard.
Bk horizon
Value: 6 or 7 dry, and 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Loam, with very gravelly and extremely gravelly modifiers.
Effervescence: Slightly effervescent through violently effervescent.
Reaction: Moderately alkaline or strongly alkaline.
Consistence: Soft to slightly hard, friable to very friable, slightly sticky to moderately sticky, and slightly plastic to moderately plastic.
Structure: Weak or moderate, fine or medium subangular blocky.
Calcium carbonate equivalent: 15 to 40 percent.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform: hills, mountains, and rock pediments, occurring on backslope positions.
Slopes: 1 to 70 percent
Elevations: 1,463 to 2,316 meters, higher elevations tend toward southerly aspects in Utah
Parent material: Colluvium, alluvium and residuum from limestone, calcareous sandstone, andesite, rhyolite and tuffaceous siltstone; In Nevada these soils formed in colluvium from andesite influenced by calcareous loess.
Mean annual precipitation: 200 to 300 mm
Mean annual temperature: 7 to 11 degrees C.
Frost-free period: 100 to 160 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Declo, Hiko Peak, and Promo soils. Declo and Hiko Peak soils are on fan remnants and are very deep. Promo soils are on hills and do not have calcic horizons.
DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; moderate permeability; moderately high saturated hydraulic conductivity.
USE AND VEGETATION: Tarnach soils are used for livestock grazing. The potential vegetation is black sagebrush, Nevada bluegrass, Indian ricegrass, and bottlebrush squirreltail. Moist areas have juniper vegetation. These soils are correlated to semidesert ecological sites in Utah.
DISTRIBUTION AND EXTENT: Northwestern Utah and northeastern Nevada. These soils are extensive. MLRAs 28A and 28B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: Box Elder County, Utah, Western Part, 1985.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A, Bk1 and part of Bk2 horizons).
Calcic horizon - The zone from 10 to 38 cm (Bk1 and Bk2 horizons).
Lithic contact - The boundary at 38 cm to underlying hard bedrock (R layer).
Particle-size control section - The zone from 25 to 38 cm (part of the Bk2 horizon).
The active cation exchange activity class was added to the taxonomic classification in December 2002 based on soil property data.
The classification was changed from Lithic Xerollic Calciorthids to Lithic Xeric Haplocalcids in 9/94.
ADDITIONAL DATA: Previous authors and editors include: JCL-RLT-MJD.