LOCATION LEO                     NV+UT

Established Series
Rev. JBF/BKP
06/2016

LEO SERIES

The Leo series consists of very deep, excessively drained soils that formed in alluvium from mixed rocks. Leo soils are on alluvial fans, mountain valley fans, fan remnants, inset fans, and fan skirts. Slopes are 0 to 15 percent. The mean annual precipitation is about 200 mm and the mean annual temperature is about 12 degrees C.

TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Typic Torriorthents

TYPICAL PEDON: Leo gravelly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The surface is partially covered with 25 percent gravel.

A--0 to 13 cm; pale brown (10YR 6/3) gravelly sandy loam, dark grayish brown (10YR 4/2) moist; weak thick platy structure; soft, very friable, nonsticky and nonplastic; common very fine, and fine roots; common very fine vesicular and many very fine interstitial pores; 25 percent gravel; moderately alkaline (pH 8.2); clear smooth boundary. (8 to 18 cm thick)

C1--13 to 38 cm; light brownish gray (10YR 6/2) gravelly fine sandy loam, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium roots; common very fine tubular; strongly effervescent; 5 percent cobbles and 25 percent gravel; moderately alkaline (pH 8.2); clear wavy boundary. (13 to 33 cm thick)

C2--38 to 71 cm; light brownish gray (10YR 6/2) very gravelly loamy coarse sand, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, nonsticky and nonplastic; ; common very fine and fine and few medium roots; common very fine and fine interstitial pores; few thin randomly oriented calcium carbonate and silica coatings on rock fragments; strongly effervescent; 5 percent cobbles and 40 percent gravel; moderately alkaline (pH 8.2); clear smooth boundary. (15 to 150 cm thick)

C3--71 to 102 cm; grayish brown (10YR 5/2) extremely gravelly coarse sand, dark grayish brown (10YR 4/2) moist; single grain; loose, nonsticky and nonplastic; common very fine and fine roots; many very fine interstitial pores; few thin randomly oriented calcium carbonate and silica coatings on rock fragments; strongly effervescent; 5 percent cobbles and 60 percent gravel; moderately alkaline (pH 8.4); clear smooth boundary. (0 to 50 cm thick)

C4--102 to 152 cm; grayish brown (10YR 5/2) very gravelly coarse sand, dark grayish brown (10YR 4/2) moist; single grain; loose, nonsticky and nonplastic; few very fine and common fine roots; many very fine interstitial pores; very few thin randomly oriented calcium carbonate and silica coatings on rock fragments; 50 percent gravel; strongly effervescent; strongly alkaline (pH 8.6).

TYPE LOCATION: Lincoln County, Nevada; approximately 4 miles southwest of Delamar ghost town about 2,250 feet west and 1,600 feet north of the southeast corner of Section 8, T. 6 S., R. 64 E; USGS Delamar 7.5 minute topographic quadrangle; latitude 37 degrees 26 minutes 20 seconds N and longitude 114 degrees 50 minutes 19 seconds W; WGS84 Decimal Degrees 37.4388889 latitude, -114.8386111 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in some part for short periods during winter and early spring months and for 10 to 20 days cumulative between July and October due to convection storms; typic aridic soil moisture regime.
Soil temperature: 12 to 15 degrees C.
Soil reaction: Moderately alkaline through strongly alkaline.

Particle-size control section - Clay content: Averages 5 to 12 percent.
Rock fragments: Averages 35 to 60 percent, dominantly gravel.
Other features: A strata of sandy loam or fine sandy loam exists within the particle-size control section.

A horizon
Value: 5 through 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Effervescence: Noneffervescent through strongly effervescent.

C1 horizon
Value: 5 through 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Texture: Fine sandy loam, sandy loam, sand, loamy sand, loamy fine sand or coarse sand.
Rock fragments: Averages 15 to 60 percent.
Texture modifiers: Gravelly or very gravelly.
Effervescence: Slightly effervescent through strongly effervescent.
Other features: Strong influence from pyroclastic materials. Some pedons have randomly oriented silica and secondary calcium carbonate concretions on rock fragments.

C2, C3 and C4 horizons
Value: 5 through 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Texture: Dominantly loamy sand, loamy fine sand, coarse sand or sand. Strata of fine sandy loam, sandy loam, and gravel layers may be present.
Rock fragments: Averages 35 to 60 percent. Individual strata may range from 10 to 100 percent rock fragments.
Consistence: Loose or soft dry, loose or very friable moist.
Structure: Massive or single grain.
Effervescence: Slightly effervescent through strongly effervescent.
Other features: Strong influence from pyroclastic materials. Some pedons have randomly oriented silica and secondary calcium carbonate concretions on rock fragments.

COMPETING SERIES: These are the Bluewing Gynelle, Inmo, Ioka, Itme, Izamatch, Izo, Nepalto, Wardenot and Willwood series.

Bluewing and Inmo soils are dry through July through October. Gynelle soils have a 2Bk horizon and have electrical conductivity of more than 4 mmhos/cm. Ioka and Willwood soils have a mean annual soil temperature of less than 10 degrees C. Itme soils have dominantly 2 to 5 mm gravel. Izamatch and Wardenot soils regularly have pedogenic calcium carbonate accumulations on the bottom of rock fragments as indicated Bk and Ck horizons. Izo and Willwood soils lack strata of sandy loam or fine sandy loam in the particle-size control section. Nepalto soils have hue of 2.5YR and average rock fragment sizes greater than 75 mm.

GEOGRAPHIC SETTING: Leo soils are on alluvial fans, inset fans, fan remnants, fan piedmonts, mountain valley fans and fan skirts. Leo soils formed in alluvium derived from mixed rock sources. Slopes are 0 to 15 percent. Elevations range from 1,178 to 2,130 meters. The mean annual precipitation is about 125 to 200 mm; the mean annual temperature is 9 to 12 degrees C. The frost-free season is 100 to 150 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Delamar, Pahroc, and Tybo soils. Delamar soils are moderately deep to an indurated duripan. Pahroc soils are shallow to an indurated duripan. Tybo soils are very shallow and shallow to a duripan.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Excessively drained; runoff is very low to medium; high saturated hydraulic conductivity.

USE AND VEGETATION: Leo soils are used for livestock grazing, irrigated cropland and wildlife habitat. The vegetation consists mainly of Nevada ephedra, spiny hopsage and desert needlegrass. Alfalfa and small grains are the principal irrigated crops.

DISTRIBUTION AND EXTENT: South-central Nevada and possibly Utah. These soils are extensive. MLRA 28A and 29.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Esmeralda County, Nevada, 1984.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A and part of C1 horizons).
Particle-size control section - The zone from 25 to 100 cm (Part of the C1, C2 and part of the C3 horizons).

ADDITIONAL DATA: Previous authors and editors include: TM/WED/RLB. The type location was moved 1/2013 to Lincoln County, Nevada, South Part to better reflect the series concept.
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National Cooperative Soil Survey
U.S.A.