LOCATION LASTONE                 NV

Established Series
REV: DJM/LJL/ET
09/2015

LASTONE SERIES

The Lastone series consists of very shallow and shallow, somewhat excessively drained soils that formed in residuum and colluvium from sandstone and siltstones. Lastone soils are on mountains. Slope ranges from 15 to 75 percent. The mean annual precipitation is about 14 inches and the mean annual temperature is about 48 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic, shallow Ustic Haplargids

TYPICAL PEDON: Lastone gravelly sandy loam, forest and wildlife habitat. (Colors are for dry soil unless otherwise noted.) The soil surface is covered by approximately 25 percent pebbles and 5 percent cobbles.

A--0 to 2 inches; brown (7.5YR 4/3) gravelly sandy loam, dark brown (7.5YR 3/2) moist; strong thick platy structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; common very fine and fine interstitial pores; 20 percent pebbles and 5 percent cobbles; slightly alkaline (pH 7.8); clear smooth boundary. (1 to 4 inches thick)

Bt--2 to 9 inches; reddish brown (5YR 4/4) extremely gravelly sandy loam, dark reddish gray (5YR 4/2) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine and coarse roots; few very fine and fine tubular pores; many, distinct, reddish brown (5YR 4/4) clay films between sand grains and on rock fragments; 70 percent pebbles, 5 percent paragravels and 5 percent cobbles; very slightly effervescent (2 percent calcium carbonate equivalent in the fine earth fraction); slightly alkaline (pH 7.8); gradual wavy boundary. (5 to 10 inches thick)

Cr--9 to 14 inches; reddish brown (5YR 5/4) weathered siltstone bedrock, dark reddish brown (5YR 3/3) moist; common fine and medium roots in the upper two inches in fractures; moderately alkaline (pH 8.0); abrupt smooth boundary. (2 to 6 inches thick)

R--14 inches; slightly fractured siltstone.

TYPE LOCATION: Clark County, Nevada; about 1/3 of a mile west of Lovell Canyon summit on the north side of the road in the south end of the Spring Mountain Range; in an unsectioned area 2,200 feet south and 7,200 feet west of the southeast corner of section 36, T. 20 S., R. 57 E.; USGS LaMadre Spring, NV. 7.5 minute topographic quadrangle; 36 degrees 9 minutes 56 seconds north latitude and 115 degrees 36 minutes 40 seconds west longitude; UTM 11s, 0624847e, 4003203n: NAD 83.

RANGE IN CHARACTERISTICS:

Soil moisture - usually dry, moist in late winter and early spring and intermittently moist in the upper part following summer convection storms; aridic soil moisture regime bordering on ustic.

Soil temperature - 47 to 52 degrees F.
Depth to argillic horizon: 1 to 4 inches.
Depth to paralithic contact: 8 to 14 inches.
Depth to hard bedrock: 10 to 20 inches.

Control section - Clay content: Averages 8 to 18 percent.
Rock fragments: Averages 45 to 80 percent mainly gravel, including 5 to 10 percent paragravel.
Reaction: Slightly alkaline or moderately alkaline.

A horizon - Hue: 7.5 YR or 5YR
Chroma: 3 or 4 dry, 2 or 3 moist.
Organic matter: 1.5 to 3.0 percent.

Bt horizon - Value: 3 or 4 moist.
Clay content: 10 to 20 percent.
Structure: Strong or moderate, fine or medium subangular blocky.
Reaction: Slightly alkaline or moderately alkaline.
Texture of the fine earth: Sandy loam or loam.
Consistence: Very friable or friable.
Organic matter: 1.0 to 2.0 percent.

COMPETING SERIES: These are the Cetrepas (NV), McClanahan (NV) and Zaqua (NV) series. Cetrepas soils have soil temperatures of 54 to 58 degrees F. and a clay content in the argillic horizon that ranges 18 to 27 percent. McClanahan soils have soil temperatures of 54 to 58 degrees F. and have a control section clay content that averages 18 to 27 percent. Zaqua soils have soil temperatures of 54 to 58 degrees F. and have a control section clay content that averages 27 to 35 percent.

GEOGRAPHIC SETTING: Lastone soils are on mountains. These soils formed in residuum and colluvium from sandstone and siltstones. Slope ranges from 15 to 75 percent. Elevations are 4,900 to 7,400 feet. The climate is sub-humid continental, cool, with moist winters and occasional summer convection storms. The mean annual precipitation is 12 to 16 inches; mean annual temperature is 45 to 50 degrees F., and the frost-free season is 90 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: This is the Traley series. Traley soils are moderately deep and have a calcic horizon.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained; very high runoff; moderate permeability.

USE AND VEGETATION: These soils are used for forest and wildlife habitat. The present vegetation is mainly singleleaf pinyon, Utah serviceberry, Gambels oak, yellowleaf silktassel, ceanothus and some Utah juniper.

DISTRIBUTION AND EXTENT: Mojave Desert of southern Nevada; MLRA 30. These soils are not extensive.

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

SERIES ESTABLISHED: Clark County Area, Nevada, 2006. Proposed in Clark County, Nevada, Clark County Soil Survey Area, 2006. The name is coined.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon -- 0 to 2 inches (A horizon).
Argillic horizon -- 2 to 9 inches (Bt horizon).
Paralithic contact -- 9 inches (Cr layer).
Hard bedrock -- 14 inches (R layer).
Particle-size control section --0 to 9 inches (A and Bt horizons).

Responsibility for this series was transferred from Davis to Phoenix 9/2015. The last revision to the series was 7/2006. ET

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National Cooperative Soil Survey
U.S.A.