LOCATION ZEPHAN NV+CAEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Xeric Haplargids
TYPICAL PEDON: Zephan gravelly sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
Al--0 to 5 cm; brown (10YR 5/3) gravelly sandy loam, brown (10YR 4/3) moist; moderate fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine, fine, and medium roots; many very fine, fine, and medium pores; 20 percent pebbles, 5 percent cobbles and 2 percent stones; moderately acid (pH 6.0); clear smooth boundary. (3 to 10 cm thick)
A2--5 to 20 cm; pale brown (10YR 6/3) gravelly loam, dark yellowish brown (10YR 4/4) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine pores; 25 percent pebbles; moderately acid (pH 6.0); clear smooth boundary. (0 to 20 cm thick)
Bt1--20 to 28 cm; light yellowish brown (10YR 6/4) gravelly clay loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; hard, friable, sticky and slightly plastic; common fine and very fine roots; common fine and very fine pores; few thin clay films on peds; l5 percent pebbles; slightly acid (pH 6.3); clear wavy boundary. (0 to 20 cm thick)
Bt2--28 to 66 cm; brown (7.5YR 5/4) very cobbly clay, dark yellowish brown (10YR 4/4) moist; weak coarse prismatic structure; very hard, firm, sticky and plastic; few medium and coarse roots; few medium pores; common moderately thick clay films on peds; 40 percent decomposing coarse fragments; moderately acid (pH 6.l); clear wavy boundary. (25 to 50 cm thick)
Bt3--66 to 89 cm; brown (7.5YR 5/4) extremely cobbly clay, strong brown (7.5YR 5/6) moist; massive; very hard, firm, sticky and plastic; very few roots; very few pores; few moderately thick clay films in pores; 60 percent decomposing coarse fragments; slightly acid (pH 6.2); gradual irregular boundary. (20 to 36 cm thick)
Cr--89 to 107 cm; weathered rhyolite. (3 to 20 inches thick)
R--107 cm; hard rhyolite.
TYPE LOCATION: Washoe County, Nevada; about l50 yards south above the railroad tracks and 300 yards north of the water tank in a little valley just south of Panther Valley; about 2,500 feet east and l00 feet south of the northwest corner of section 26, T. 20 N., R. 20 E. latitude 39 degrees 34 minutes 39 seconds N and longitude 119 degrees 42 minutes 20 seconds W; NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually dry, moist in winter and spring, aridic soil moisture regime bordering on xeric.
Mean annual soil temperature - 9 to 12 degrees C.
Depth to paralithic contact - 64 to 100 cm.
Depth to hard bedrock - 100 to 125 cm.
Particle-size control section - Clay content: 35 to 45 percent.
Rock fragments: 35 to 60 percent.
A horizon - Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 through 4.
Reaction: Moderately acid to neutral.
B horizon - Hue: 10YR or 7.5YR.
Value: 4 through 6 dry, 4 or 5 moist.
Chroma: 3 or 4 dominantly, but may be as high as 6 in the lower part of some pedons.
Textures: Clay, sandy clay, subhorizons may be sandy clay loam or heavy clay loam.
C horizon - Other features: A thin medium acid or strongly acid C horizon occurs above bedrock in some pedons.
COMPETING SERIES: These are the Berning, Bilbo, Clenage, Havingdon, Lambranch, Maderbak, Pula, Surgen, Tanawit, Tenmile and Vanwyper series.
Berning, Bilbo, Lambranch, Pula, Tanawit, and Tenmile soils lack bedrock within 100 cm. Cleanage, Havingdon, Maderbak, Surgen, and Vanwyper soils have hard bedrock within 100 cm.
GEOGRAPHIC SETTING: Zephan soils are on plateaus, hills and mountains. These soils formed in residuum and colluvium from rhyolite and altered andesite. Slopes are 4 to 50 percent. Elevations are 1,370 to 1,980 meters. The climate is semiarid. The mean annual precipitation is 200 to 300 mm; mean annual temperature is 8 to 1l degrees C.; mean January temperature is -1 to 0 degrees C.; mean July temperature is 19 to 21 degrees C.; and the frost-free season is 80 to ll0 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Manogue, Mizel, Wedekind, and Xman soils. Manogue soils are Vertisols. Mizel soils are shallow and lack an argillic horizon. Wedekind soils are loamy, shallow, and have a mollic epipedon. Xman soils have less than 30 percent rock fragments in the particle-size control section and are shallow to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; slow permeability; moderately high or moderately low saturated hydraulic conductivity.
USE AND VEGETATION: Zephan soils are used for wildlife habitat, recreation, and urban development. Vegetation is primarily horsebrush, cheatgrass, bottlebrush squirreltail, ephedra, big sagebrush, and low sagebrush.
DISTRIBUTION AND EXTENT: Western Nevada. These soils are of small extent.
MLRA OFFICE RESPONSIBLE: Reno, Nevada
SERIES ESTABLISHED: Washoe County, South Part, Nevada, l980.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the surface to about 20 cm. (A1 and A2 horizon)
Argillic horizon - The zone from about 20 to 89 cm. (Bt1, Bt2 and Bt3 horizons)
Paralithic contact - The boundary at about 89 cm.
Particles-size control section - The zone from about 20 to 70 cm. (Bt1, Bt2 and upper Bt3 horizons)