LOCATION IRONPED                 CA

Established Series
Rev: CAH/ET
04/2015

IRONPED SERIES

The Ironped series consists of very shallow and shallow, somewhat excessively drained soils that formed in granitic, granitoid,and gneissic residuum and colluvium. The Ironped soils are on pediments, hills and mountains. Slopes range from 2 to 60 percent. The mean annual precipitation is about 125 millimeters (5 inches) and the mean annual air temperature is about 18.5 degrees C (65 degrees F).

TAXONOMIC CLASS: Mixed, thermic, shallow Typic Torripsamments

TYPICAL PEDON: Ironped gravelly loamy sand, on a linear, 5 percent slope at an elevation of 1098 meters. (Colors are for dry soil unless otherwise noted.) The surface is covered by approximately 50 percent gravel.

A -- 0 to 4 centimeters (0 to 2 inches); very pale brown (10YR 7/4) gravelly loamy sand, dark yellowish brown (10YR 4/4) moist; moderate thick platy structure; soft, very friable, nonsticky and nonplastic; common very fine roots; common very fine tubular pores; 30 percent gravel; very slightly effervescent; slightly alkaline (pH 7.4); clear wavy boundary. (2 to 13 centimeters thick)

Bw -- 4 to 15 centimeters (2 to 6 inches); light yellowish brown (10YR 6/4) gravelly loamy sand, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; common very fine tubular pores; 25 percent gravel; very slightly effervescent; slightly alkaline (pH 7.6); abrupt wavy boundary. (0 to 27 centimeters thick)

Crtk -- 15 to 150 centimeters (6 to 60 inches); slightly weathered granitic bedrock (fractures greater than 10 centimeters apart) with slight to moderate excavation difficulty; common very fine, few fine and medium roots in fractures; 30 percent distinct, strong brown (7.5YR 5/6) clay films in fractures and on rock fragments; 1 percent distinct, fine, white (10YR 8/1) calcium carbonate threads on rock fragments; 5 percent distinct, white (10YR 8/1) calcium carbonate coats on rock fragments.

TYPE LOCATION: San Bernardino County, California; approximately 1.0 kilometers west of the Iron Ridge Mountains; 0.7 kilometers south and 0.1 kilometers west of the NE corner of sec. 20, T. 6 N., R. 4 E., San Bernardino Base and Meridian; 34 degrees, 35 minutes and 51.1 seconds north latitude and 116 degrees, 34 minutes and 32.0 seconds west longitude; USGS Iron Ridge 7.5 minute quadrangle; UTM 11S 538919e 3828494n (DTM: NAD83).

RANGE IN CHARACTERISTICS:

Soil moisture control section: Usually dry, moist in some parts for short periods during winter and early spring and for 10 to 20 days cumulative between July and September following summer convection storms. The soils have a typic-aridic soil moisture regime.

Soil temperature: 19 to 22 degrees C.

Surface rock fragments: ranges from 5 to 80 percent; with 5 to 70 percent finegravel, 0 to 15 percent medium and coarse gravel, 0 to 5 percent cobbles and 0 to 2 percent stones.

Control section
Rock fragments: 2 to 34 percent, 0 to 30 percent gravel and 0 to 5 percent cobbles.
Organic matter: 0 to 0.5 percent
Clay content: 2 to 8 percent.
Depth to paralithic contact: 5 to 35 centimeters (2 to 14 inches).

A horizon
Value: 5 to 7 dry, and 3 to 5 moist.
Chroma: 3 to 5, moist.
Texture of the fine earth: sand or loamy sand.
Clay content: 3 to 8 percent.
Rock fragments: 2 to 34 percent, 0 to 30 percent gravel and 0 to 5 cobbles.
Effervescence: noneffervescent to slightly effervescent.
Reaction: slightly acid to moderately alkaline.

Bw horizon (when present)
Value: 3 to 6 dry, and 3 to 5 moist.
Chroma: 3 to 6, dry or moist.
Clay content: 2 to 8 percent.
Texture of the fine earth: coarse sand, sand and loamy sand.
Rock fragments: 2 to 30 percent, 0 to 20 percent gravel and 0 to 10 percent cobbles.
Effervescence: noneffervescent to violently effervescent.
Reaction: neutral to moderately alkaline.

COMPETING SERIES: These are the Jawbone (CA) and Pinecity (CA) series. Jawbone soils are not moist in the moisture control section for 10 to 20 days following summer convection storms. Pinecity soils have a mean annual soil temperature of 15 to 19 degrees.

GEOGRAPHIC SETTING: Ironped soils are on pediments, hills and mountains. Slopes range from 2 to 60 percent. These soils formed in granitic, granitoid and gneissic residuum and colluvium. Elevations range from 700 to 1,440 meters (2,300 to 4,700 feet). The climate is arid with hot, dry summers and warm, moist winters. The mean annual precipitation is 75 to 175 millimeters (3 to 7 inches, mean annual air temperature is 17 to 20 degrees C, and the frost-free season is 270 to 320 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cougarbutte, Gravesumit, Hexie, Lostpalms, Pinecity, and Silvermine soils. Cougarbutte soils are on fan aprons over pediments and have a loamy particle size control section. Gravesumit and Silvermine soils are on nearby fan remnants. Gravesumit soils are very deep and have an argillic and a calcic horizon, and a coarse-loamy particle-size control section. Silvermine soils are shallow to a weakly cemented duripan. Hexie soils are on mountain backslopes and are moderately deep to a paralithic contact. They have a coarse-loamy argillic horizon above the contact. Lostpalms soils are on steep pediments and have a shallow lithic contact and are skeletal with greater than 35 percent rock fragments. Pinecity soils are on pediments, hills or mountains, but are typically on north-facing slopes and/or at higher elevations with a cooler soil temperature regime.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat excessively drained; very low runoff on low-sloping pediment to very high runoff on steep hills and mountains; high saturated hydraulic conductivity above the weathered bedrock and moderately high in the bedrock.

USE AND VEGETATION: Ironped soils are used for recreation and wildlife habitat. The present vegetation is mainly creosote bush and burrobush.

DISTRIBUTION AND EXTENT: Southern Mojave Desert of southeastern California. MLRA 30. These soils are of moderate extent.

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

SERIES ESTABLISHED: San Bernardino County, California; Soil Survey of Joshua Tree National Park, California, 2012. The name is coined.

REMARKS: Diagnostic horizons and features recognized in the profile include:

Ochric epipedon - from a depth of 0 to 15 centimeters (A and Bw horizons).
Paralithic contact - the zone beginning at 15 centimeters (Crtk).
Particle size control section - from a depth of 0 to 15 centimeters (A and Bw horizons).

Responsibility for this series was transferred from Davis to Phoenix 4/2015. The last revision to the series was 5/2012. ET

---

National Cooperative Soil Survey
U.S.A.