LOCATION FOURCORNERS CA
Established Series
REV: PBF/ET
04/2015
FOURCORNERS SERIES
The Fourcorners series consists of very shallow and shallow, well drained soils that formed in mixed alluvium. Fourcorners soils are on fan remnants. Slope ranges from 4 to 30 percent. The mean annual precipitation is about 4 inches and the mean annual air temperature is about 67 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic, shallow Typic Argidurids
TYPICAL PEDON: On Fourcorners extremely gravelly sandy loam, 4 to 30 percent slopes at an elevation of 2,050 feet. (Colors are for dry soil unless otherwise noted.) The surface is covered by approximately 60 percent gravel, 15 percent cobbles and 10 percent stones.
A -- 0 to 1 inch; very pale brown (10YR 7/4) extremely gravelly sandy loam, yellowish brown (10YR 5/6) moist; moderate fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; many very fine vesicular pores; noneffervescent; 60 percent gravel, 15 percent cobbles, and 10 percent stones; slightly alkaline (pH 7.8); abrupt smooth boundary. (1 to 7 inches thick)
Bt -- 1 to 7 inches; reddish yellow (7.5YR 6/6) very gravelly sandy loam, strong brown (7.5YR 5/6) moist; weak very fine and fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; common fine, few very fine tubular and interstitial pores; 70 percent faint discontinuous clay films on ped faces and distinct patchy clay films on sands and gravel; few distinct carbonate coats on lower surfaces of peds or rocks; slightly effervescent; 30 percent gravel, 10 percent cobbles, and trace of stones; moderately alkaline (pH 8.0); abrupt wavy boundary. (4 to 9 inches thick)
Bkqm -- 7 inches; very pale brown (10YR 8/2) indurated duripan, very pale brown (10YR 7/3) moist.
TYPE LOCATION: San Bernardino County, California; about 6 miles east and 3,500 feet north of the airfield base buildings at Bicycle Lake, Fort Irwin, California in an unsectionalized area; 6,400 feet north and 1,150 west of the northwest corner of section 1, T. 13 N., R. 4 E., 35 degrees, 16 minutes, 22 seconds north latitude and 116 degrees, 31 minutes, 16 seconds west longitude; Tiefort Mountains USGS 7.5 minute quadrangle; (UTM 11S, 0543548e 3903390n)
RANGE IN CHARACTERISTICS:
Soil moisture control section: Usually dry, moist in some part for short periods during winter and early spring and for 10 to 20 days cumulative between July and October following convection storms. The soils have a Typic-Aridic moisture regime.
Soil temperature: 66 to 72 degrees F.
Surface rock fragments: 50 to 65 percent gravel, 3 to 30 percent cobbles, and 2 to 10 percent stones.
Control section -
Depth to duripan: 7 to 14 inches
Rock fragments: range is from 40 to 55 percent; mostly gravel and cobbles
Clay content: 12 to 25 percent
Reaction: slightly or moderately alkaline
Organic matter: 0 to 0.5 percent
A horizon
Value: 5 to 7 dry, and 4 or 5 moist
Chroma: 3 or 4 dry, and 3 to 6 moist
Clay content: 8 to 12 percent
Rock fragments: 35 to 85 percent; with 10 to 60 percent
gravel, 2 to 25 percent cobbles, and 0 to 10 percent
stones
Consistence: soft or slightly hard, very friable or
friable
Effervescence: noneffervescent to strongly effervescent
Reaction: slightly or moderately alkaline
Bt horizon
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, and 4 or 5 moist
Chroma: 4 to 6 dry, and 4 to 8 moist
Texture of the fine earth: sandy loam, loam or sandy clay
loam
Rock fragments: 35 to 75 percent; with 15 to 50 percent
gravel and 2 to 40 percent cobbles
Consistence: slightly hard to hard, very friable to firm
Effervescence: noneffervescent to strongly effervescent
Calcium carbonate equivalence: 0 to 1 percent
Reaction: slightly or moderately alkaline
COMPETING SERIES: These are the
Dedas (NV) and
Peloncillo (AZ) series. Dedas soils have a thin duripan over bedrock. Bedrock is at a depth of 16 to 24 inches. Peloncillo soils are moist in some part of the moisture control section for more than 20 days cumulative during July to September.
GEOGRAPHIC SETTING: Fourcorners soils are on fan remnants and ballenas. Slope ranges from 4 to 30 percent. The soils formed in mixed alluvium. Elevations are 2,000 to 3,000 feet. The climate is arid with hot, dry summers and warm, moist winters. Most precipitation occurs in winter but a significant portion is received between July and September following convection storms. The mean annual precipitation is 3 to 5 inches; mean annual air temperature is 64 to 70 degrees F., and the frost-free season is 300 to 340 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Arizo,
Dalvord,
Goldroad, and
Nellake soils. Arizo soils do not have an argillic horizon, have a sandy-skeletal particle-size control section, and are on inset fans and alluvial fans. Dalvord and Goldroad soils do not have an argillic horizon and are found on adjacent mountains. In addition, Goldroad soils have a hyperthermic soil temperature regime. Nellake soils are very deep and are found on similar landscapes and fan piedmonts.
DRAINAGE AND PERMEABILITY: Well drained; very low to medium runoff; moderately rapid to moderately slow permeability.
USE AND VEGETATION: Fourcorners soils are used for military exercises and wildlife habitat. The present vegetation is mainly creosotebush and white bursage.
DISTRIBUTION AND EXTENT: Mojave Desert of southeastern California. MLRA 30. These soils are of small extent in MLRA 30.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: PHOENIX, ARIZONA
SERIES PROPOSED: San Bernardino County, California, Fort Irwin Soil Survey Area, 1997. The name is from a location in the survey area.
REMARKS: Diagnostic horizons and features recognized in the profile are:
1. Ochric epipedon -- 0 to 1 inch (A horizon)
2. Argillic horizon -- 1 to 7 inches (Bt horizon)
3. Duripan -- The zone beginning at 7 inches.
Responsibility for this series was transferred from Davis to Phoenix 4/2015. The last revision to the series was 4/2000. ET
National Cooperative Soil Survey
U.S.A.