LOCATION LASTCHANCE NV

Established Series
Rev. LJL/TM/ET
09/2015

LASTCHANCE SERIES

The Lastchance series consists of moderately deep to a petrocalcic, well drained soils that formed in alluvium derived from limestone and dolomite. Lastchance soils are on fan remnants. Slope ranges from 2 to 15 percent. The mean annual precipitation is about 6 inches and the mean annual air temperature is about 62 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, carbonatic, thermic Calcic Petrocalcids

TYPICAL PEDON: Lastchance extremely gravelly loam, rangeland and wildlife habitat. (Colors are for dry soil unless otherwise noted.) The soil surface is covered by approximately 60 percent pebbles and 10 percent cobbles.

ABt--0 to 2 inches; very pale brown (10YR 7/4) extremely gravelly loam, yellowish brown (10YR 5/4) moist; moderate very thick platy structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine, common fine and medium vesicular pores; few faint clay films on bottoms of peds and lining vesicular pores in the upper inch; 60 percent pebbles and 5 percent cobbles; violently effervescent; strongly alkaline (pH 8.8 ); clear wavy boundary. (1 to 4 inches thick)

Bk1--2 to 11 inches; very pale brown (10YR 7/4) very gravelly loam, yellowish brown (10YR 5/4) moist; massive; soft, very friable, slightly sticky and slightly plastic; many very fine roots, few fine and medium roots; common very fine and few fine interstitial and tubular pores; few fine soft masses of calcium carbonate; many (50 percent) patchy thin (< 1 mm) calcium carbonate coatings on undersides of rock fragments; 40 percent pebbles and petrocalcic fragments, and 5 percent cobbles; violently effervescent; moderately alkaline (8.4 pH); clear wavy boundary.

Bk2--11 to 20 inches; very pale brown (10YR 7/4) very gravelly loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, firm, slightly sticky and slightly plastic; few very fine roots; few very fine and fine interstitial and tubular pores; common (5 percent) soft masses of calcium carbonate; many (75 percent) thick (1 to 20 mm) calcium carbonate coatings on rock fragments; 45 percent pebbles and petrocalcic fragments, and 5 percent cobbles; violently effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (The combined thickness of the Bk horizons is 16 to 29 inches.)

Bkqm--20 to 60 inches; very pale brown (10YR 8/3) very strongly cemented petrocalcic, very pale brown (10YR 7/3) and light yellowish brown (10YR 6/4) moist; massive; very rigid and very rigid; 40 percent discontinuous strata and lenses of weakly cemented material in the lower part.

TYPE LOCATION: Nye County, Nevada; approximately 3 miles northeast of Pahrump on the road to Horse Springs; about 550 feet south and 100 feet east of the northwest corner of section 8, T. 20 S., R. 54 E.; USGS Pahrump, NV 7.5 minute topographic quadrangle; 36 degrees, 14 minutes, 1 seconds north latitude and 115 degrees, 56 minutes, 29 seconds west longitude; UTM 11S, 595122e, 4010371n; NAD 83.

RANGE IN CHARACTERISTICS:

Soil moisture - Usually dry, moist in some during winter and spring and intermittingly moist in the upper part following summer convection storms; typic-aridic soil moisture regime.

Soil temperature - 59 to 66 degrees F.

Depth to petrocalcic horizon - 20 to 30 inches.

Control section - Percent clay: 8 to 18 percent.
Rock fragments: 35 to 70 percent, mainly petrocalcic fragments.
Calcium carbonate equivalent in the fine earth fraction: 20 to 50 percent; less than 20 millimeter fraction averages 40 to 70 percent.

ABt horizon - Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 through 4.
Reaction: Moderately alkaline or strongly alkaline.
Other features: In most pedons, clay films and silt coats commonly occur in the upper part and textures are heavier than underlying horizons due to additions of dust.

Bk or Bkq horizons - Value: 6 or 7 dry.
Chroma: 3 or 4.
Texture: Loam, fine sandy loam, sandy loam.
Rock fragments: 35 to 70 percent, mainly petrocalcic fragments and limestone or dolomite pebbles.
Reaction: Moderately alkaline or strongly alkaline.
Other features: Identifiable secondary carbonates are calcium carbonate coatings on rock fragments and soft masses. Few thin silica coatings are on rock fragments in some pedons.

Bkqm horizon - Value: 7 or 8 dry.
Structure: Massive or platy.
Pan thickness: Greater than 3 feet thick.
Cementation: Very strongly cemented or indurated, lenses of weakly or moderately cemented material are in the lower part.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Lastchance soils are on fan remnants. These soils formed in alluvium derived from limestone and dolomite. Slope ranges from 2 to 15 percent. Elevations are 2,800 to 4,600 feet. The climate is typical of the Mojave desert, with cool, moist winters and hot, dry summers. The mean annual precipitation is 4 to 7 inches; mean annual air temperature is 57 to 64 degrees F., and the frost-free period is 180 to 250 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arizo, Commski, and Ferrogold series. Arizo and Commski soils lack petrocalcic horizons and are on inset fans and drainageways. Ferrogold soils are shallow to petrocalcic horizons and are on higher elevation fan remnants with blackbrush vegetation.

DRAINAGE AND PERMEABILITY: Well drained; high runoff; moderate permeability.

USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. The present vegetation is mainly white bursage, creosotebush, Spanish dagger, Anderson wolfberry, spiny menodora, winterfat and range ratany.

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: Nye County, Nevada, Southwest Part, 2001.

REMARKS: The name is coined from the Last Chance Range of hills to the west.

Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 2 inches (ABt horizon).
Calcic horizon - 2 to 20 inches (Bk1 and Bk2 horizons).
Petrocalcic horizon - 20 to 60 inches (Bkqm horizon).
Particle-size control section - 10 to 20 inches (Part of the Bk1 and Bk2 horizons).

Responsibility for this series was transferred from Davis to Phoenix 9/2015. The last revision to the series was 3/2006. ET

National Cooperative Soil Survey
U.S.A.