LOCATION MCWATT NV+CAEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Xeric Haplocambids
TYPICAL PEDON: Mcwatt extremely cobbly fine sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partly covered with 15 percent stones, 20 percent cobbles, and 20 percent pebbles.
A--0 to 4 inches; pale brown (10YR 6/3) extremely cobbly fine sandy loam, dark brown (10YR 3/3) moist; moderate thin and medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine and fine vesicular pores; 15 percent stones, 20 percent cobbles, and 30 percent gravel; neutral (pH 6.8); clear wavy boundary. (2 to 5 inches thick)
Bw1--4 to 10 inches; light brownish gray (10YR 6/2) extremely cobbly fine sandy loam, dark brown (10YR 3/3) moist; strong medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; many very fine tubular pores; 15 percent stones, 20 percent cobbles, and 30 percent gravel; neutral (pH 7.2); clear wavy boundary. (0 to 8 inches thick)
Bw2--10 to 20 inches; pale brown (10YR 6/3) extremely gravelly fine sandy loam, dark brown (10YR 3/3) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine, common fine and medium roots; many very fine interstitial pores; 3 percent stones, 20 percent cobbles, and 50 percent gravel; neutral (pH 7.2); clear irregular boundary. (7 to 12 inches thick)
2Cqk1--20 to 25 inches; light yellowish brown (10YR 6/4) extremely cobbly loamy sand, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, nonsticky and nonplastic; many very fine and fine, common medium and few coarse roots; many very fine interstitial pores; 10 percent stones, 35 percent cobbles, and 40 percent gravel; secondary carbonates and silica segregated as thin (<0.5 millimeter) coats on 30 percent of the bottoms of rock fragments; slightly alkaline (pH 7.6); clear irregular boundary. (5 to 23 inches thick)
2Cqk2--25 to 44 inches; light yellowish brown (10YR 6/4) extremely gravelly sand, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine, few medium and coarse roots; many very fine interstitial pores; 5 percent stones, 15 percent cobbles, and 50 percent gravel; secondary carbonates and silica segregated as thin (<0.5 millimeter) coats on 60 percent of the bottoms of rock fragments; slightly alkaline (pH 7.6); abrupt irregular boundary. (10 to 31 inches thick)
3R--44 inches; hard, vesicular basalt; silica and secondary carbonate coats lining few fractures.
TYPE LOCATION: Washoe County, Nevada; in the Black Hills about 3.5 miles south of Road 8A along the powerline in Long Valley; in nonsectionized township T. 42 N., R. 20 E.; USGS Painted Point 7.5 minute topographic quadrangle; 41 degrees 31 minutes 59 seconds north latitude and 119 degrees 42 minutes 32 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in winter and spring, dry from mid-June through October; Aridic moisture regime that borders on xeric.
Mean annual soil temperature - 47 to 53 degrees F.
Depth to sandy-skeletal material - 15 to 26 inches.
Depth to identifiable secondary carbonates - 17 to 29 inches.
Depth to bedrock - 40 to 60 inches to a lithic contact.
Particle-size control section - Clay content: Averages 2 to 8 percent;
Rock fragments: 60 to 75 percent, mainly cobbles and gravel. Lithology of fragments are mainly volcanic rocks such as basalt.
A horizon
Hue: 10YR or 2.5Y.
Reaction: Neutral or slightly alkaline.
Bw horizons
Value: 6 or 7 dry, 3 through 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Extremely gravelly fine sandy loam, extremely cobbly fine sandy loam, or extremely gravelly sandy loam.
Clay content: 8 to 15 percent.
Reaction: Neutral or slightly alkaline.
2Cqk horizons
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Extremely cobbly loamy sand, extremely gravelly sand, or extremely gravelly loamy sand.
Clay content: 0 to 5 percent.
Rock fragments: 60 to 80 percent, mainly cobbles and gravel.
Reaction: Slightly alkaline or moderately alkaline.
Effervescence: Noneffervescent matrix.
Identifiable secondary carbonates: Few to many less than 0.5 millimeter thick carbonate and silica coats on bottoms of rock fragments.
Calcium carbonate equivalent: 1 to 3 percent.
COMPETING SERIES: These are the Broncho, Malaga, McConnel, Mcnye, and Ragnel series.
Broncho, Malaga, McConnel, and Ragnel soils are very deep. Mcnye soils are 5 to 15 inches deep to disseminated secondary carbonates.
GEOGRAPHIC SETTING: Mcwatt soils are on plateaus and lake terraces. These soils formed in alluvium derived from basalt. Slopes are 4 to 50 percent. Elevations range from 4,480 to 6,060 feet. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 8 to 10 inches, the mean annual temperature is 45 to 47 degrees F., and the frost-free period is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Langston, Old Camp, and Paypoint soils. Langston soils are fine-loamy over sandy or sandy-skeletal and have argillic horizons. Old Camp soils are loamy-skeletal, shallow to lithic contacts, and have argillic horizons. Paypoint soils are ashy over sandy or sandy-skeletal and have argillic horizons.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; low surface runoff; moderately rapid permeability (high saturated hydraulic conductivity).
USE AND VEGETATION: Mcwatt soils are used for rangeland and wildlife habitat. The present vegetation is mainly Wyoming big sagebrush, bottlebrush squirreltail, Thurber's needlegrass, and spiny hopsage.
DISTRIBUTION AND EXTENT: Northwestern Nevada and northeastern California. These soils are moderately extensive. MLRA 23.
MLRA OFFICE RESPONSIBLE: Reno, Nevada.
SERIES ESTABLISHED: Washoe County, Nevada (North Part), 1995.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 7 inches (A horizon and part of the Bw1 horizon).
Cambic horizon - The zone from 4 to 20 inches (Bw1 and Bw2 horizons).
Lithic contact - The boundary at 44 inches to underlying hard, unweathered bedrock (3R layer).
Particle-size control section - The zone from 10 to 40 inches (Bw2 and 2Cqk1 horizons and part of the 2Cqk2 horizon).