LOCATION SEARCHLIGHT NV

Established Series
Rev. LJL/BAL/ET
12/2015

SEARCHLIGHT SERIES

The Searchlight series consists of very deep, well drained soils that formed in alluvium from mixed rock sources. Searchlight soils are on fan aprons over fan remnants. Slope ranges from 2 to 8 percent. The mean annual precipitation is about 6 inches and mean annual air temperature is about 66 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Typic Haplargids

TYPICAL PEDON: Searchlight extremely gravelly sandy loam, rangeland and wildlife habitat. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with approximately 60 percent pebbles.

A--0 to 2 inches; pale brown (10YR 6/3) extremely gravelly sandy loam, brown (10YR 4/3) moist; strong thin to thick platy structure; soft, very friable, nonsticky and nonplastic; common very fine roots, many very fine and fine vesicular and interstitial pores; 60 percent pebbles; strongly effervescent (5 percent calcium carbonate equivalence in the fine earth fraction); strongly alkaline (pH 8.6); abrupt smooth boundary. (1 to 2 inches thick)

Bkq--2 to 12 inches; light brownish gray (10YR 6/2) stratified gravelly sandy loam to very gravelly loamy coarse sand, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium roots; many very fine and fine interstitial pores; averages 30 percent pebbles; strongly effervescent (5 percent calcium carbonate equivalence in the fine earth fraction); common distinct calcium carbonate and silica coats on undersides of rock fragments; strongly alkaline (pH 8.6); abrupt smooth boundary. (8 to 18 inches thick)

2Btkq1--12 to 17 inches; light brown (7.5YR 6/3) gravelly coarse sandy loam, brown (7.5YR 4/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine and few medium roots; common very fine and fine interstitial pores; many distinct colloidal stains and bridging of sand grains; few fine irregularly shaped filaments of calcium carbonate; 20 percent pebbles; strongly effervescent (5 percent calcium carbonate equivalence in the fine earth fraction); few distinct calcium carbonate and silica coats on undersides of coarse fragments; strongly alkaline (pH 8.6); abrupt smooth boundary.

2Btkq2--17 to 33 inches; very pale brown (10YR 7/3) gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky and nonplastic; few very fine and fine roots; many very fine and fine interstitial and few very fine tubular pores; many moderate colloidal stains and few thin clay skins lining pores and on faces of ped; many fine irregularly shaped filaments of calcium carbonate; 25 percent pebbles; violently effervescent (5 percent calcium carbonate equivalence in the fine earth fraction); many thin calcium carbonate and silica coats on coarse fragments; strongly alkaline (pH 8.8); clear smooth boundary. (combined thickness of the 2Btkq horizons is 10 to 31 inches thick)

2Bkq--33 to 60 inches; pale brown (10YR 6/3) stratified very gravelly loamy coarse sand to gravelly loamy coarse sand, dark yellowish brown (10YR 4/4) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine and fine interstitial pores; common fine irregularly shaped filaments of calcium carbonate; averages 41 percent pebbles; violently effervescent (7 percent calcium carbonate equivalence in the fine earth fraction); many distinct calcium carbonate and silica coats on underside of coarse fragments; strongly alkaline (pH 8.8).

TYPE LOCATION: Clark County, Nevada; approximately 4 miles south of Boulder City; about 900 feet east and 3400 feet south of the northwest corner of section 20, T. 24 S., R. 64 E. USGS Boulder City SE 7.5 minute topographic quadrangle; 35 degrees, 50 minutes, 31 seconds north latitude and 114 degrees, 51 minutes, 41 seconds west longitude; UTM 11s 0693225e, 3968330n; NAD83.

RANGE IN CHARACTERISTICS:

Soil moisture - Usually dry, moist in some part for short periods during winter and early spring and for 10 to 20 days cumulative between July to October following convection storms. The soils have a typic aridic moisture regime.

Soil temperature - 67 to 71 degrees F.

Depth to argillic horizon - 10 to 19 inches.

Depth to base of argillic horizon - 20 to 50 inches.

Calcium carbonate equivalent of the fine earth fraction: 5 to 10 percent.

Secondary calcium carbonate by volume: Less than 5 percent.

Control section - Percent clay: Averages 12 to 18 percent.

Rock fragments: Averages 15 to 35 percent gravel.

Reaction: Moderately alkaline or strongly alkaline.

A horizon - Value: 6 or 7 dry, 4 or 5 moist

Chroma: 3 or 4

C horizon - Value: 6 or 7 dry 4 or 5 moist

Chroma: 2, 3 or 4

Rock fragments: range from 15 to 50 percent.

Effervescence: Slightly effervescent to violently effervescent

2Btkqb horizons - Value: 4 or 5 moist

Chroma: 3, 4 or 6

Texture of the fine earth: Coarse sandy loam or sandy loam

Rock fragments: 15 to 35 percent, mainly gravel

Structure: Subangular blocky or massive

Effervescence: Slightly effervescent to violently effervescent

2Bkqb horizon - Value: 6 or 7 dry, 4 or 6 moist

Chroma : 3, 4 or 6

Texture of the fine earth: Loamy coarse sand or loamy sand.

Clay content: 2 to 10 percent.

Rock fragments: Averages 35 to 60 percent pebbles.

COMPETING SERIES: These are the Helendale (CA), Onite (NM), Rotura (T NM), Sonoita (AZ), Tray (CA) and Yucca (NM). Helendale, Yucca and Onite soils contain 5 to 15 percent rock fragment in the particle size control section. Sonoita soils contain less than 5 percent calcium carbonate equivalent. Tray soils have a massive horizon with an ESP of 15 to 30. Rotura soils have petrocalcic horizon at 40 to 60 inches and contain less than 5 percent gravel in the particle size control section.

GEOGRAPHIC SETTING: Searchlight soils are on fan aprons over fan remnants. These soils formed in alluvium from mixed rock sources. Slope ranges from 2 to 8 percent. Elevations are 1750 to 3400 feet. The climate is hot and arid with warm, moist winters and hot, dry summers. The mean annual precipitation is 5 to 7 inches; mean annual air temperature is 64 to 69 degrees F., and the frost-free season is 240 to 300 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arizo and Tonopah series. Arizo and Tonopah soils are sandy-skeletal and lack an argillic horizon. Tonopah soils have a calcic horizon.

DRAINAGE AND PERMEABILITY: Well drained; low runoff; moderately rapid permeability.

USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. The present vegetation is mainly creosotebush and white bursage.

DISTRIBUTION AND EXTENT: Mojave Desert of southern Nevada, U.S.A; MLRA 30.. These soils are of small extent

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: PHOENIX, ARIZONA

SERIES ESTABLISHED: Clark County (Las Vegas and Eldorado Valley Area), Nevada, 1964.

REMARKS: The type location was moved in 1997 and the series was reclassified to better represent the series concept.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - 0 to 2 inches (A horizon).

Argillic horizon - 12 to 33 inches (2Btkq1 and 2Btkq2 horizons).

Particle-size control section - 12 to 32 inches (2Btkq1 and part of the 2Btkq2 horizons).

Responsibility for this series was transferred from Davis to Phoenix 12/2015. The last revision to the series was 12/2005. ET

National Cooperative Soil Survey
U.S.A.