LOCATION SUNMILL CA

Established Series
Rev: PBF/CAH/ET
12/2015

SUNMILL SERIES

The Sunmill series consists of very deep, well drained soils that formed in alluvium from granitoid rocks. Sunmill soils are on fan remnants and fan aprons over fan remnants. Slopes range from 1 to 8 percent. The mean annual precipitation is about 100 millimeters (4 inches) and the mean annual air temperature is about 21.5 degrees C (71 degrees F).

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, hyperthermic Typic Calciargids

TYPICAL PEDON: Sunmill loamy sand, on a southeast-facing, linear, 5 percent slope under desert shrubs at an elevation of 690 meters (2,263 feet). Colors are for dry soil unless otherwise noted.) The surface is covered by approximately 30 percent fine gravel and 20 percent medium and coarse gravel.

A -- 0 to 4 centimeters (0 to 1.5 inches); very pale brown (10YR 7/4) loamy sand, yellowish brown (10YR 5/4) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; few very fine roots; few fine vesicular pores; 2 percent very pale brown (10YR 8/2) calcium carbonate coats on bottom of rock fragments; 7 percent fine gravel and 3 percent medium and coarse gravel; strongly effervescent; slightly alkaline (pH 7.7); clear smooth boundary. (2 to 6 centimeters thick)

Bk -- 4 to 26 centimeters (1.5 to 10 inches); very pale brown (10YR 7/4) loamy coarse sand, yellowish brown (10YR 5/6) moist; weak medium subangular blocky structure; loose, nonsticky and nonplastic; common very fine roots; few fine interstitial pores; 2 percent very pale brown (10YR 8/2) calcium carbonate coats on bottom of rock fragments; 5 percent fine gravel; strongly effervescent; slightly alkaline (pH 7.7); clear wavy boundary. (19 to 48 centimeters thick)

Btk1 -- 26 to 44 centimeters (10 to 17 inches); brownish yellow (10YR 6/6) sandy loam, yellowish brown (10YR 5/6) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; common very fine roots; few fine interstitial pores; 10 percent distinct, strong brown (7.5YR 5/6) clay films on ped faces; 2 percent very pale brown (10YR 8/2) calcium carbonate coats on bottom of rock fragments 5 percent fine gravel; strongly effervescent (calcium carbonate equivalent of 1 percent); slightly alkaline (pH 7.7); clear wavy boundary.

Btk2 -- 44 to 78 centimeters (17 to 31 inches); brownish yellow (10YR 6/6) sandy loam, yellowish brown (10YR 5/6) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; few fine interstitial pores; 50 percent medium and coarse, prominent, very pale brown (10YR 8/2), irregular, soft calcium carbonate masses throughout the matrix; 5 percent distinct, strong brown (7.5YR 5/6) clay films on ped faces; 5 percent fine gravel; violently effervescent (calcium carbonate equivalent of 15 percent); moderately alkaline (pH 8.2); clear wavy boundary. (Combined thickness of the Btk horizons is 10 to 90 centimeters).

B'k1 -- 78 to 91 centimeters (31 to 36 inches); very pale brown (10YR 7/3) loamy sand, light yellowish brown (10YR 6/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine roots; few fine interstitial pores; 75 percent coarse and very coarse, distinct, very pale brown (10YR 8/2), irregular, soft carbonate masses throughout matrix; 5 percent fine gravel; violently effervescent (calcium carbonate equivalent of 10 percent); moderately alkaline (pH 8.4); gradual wavy boundary.

B'k2 -- 91 to 137 centimeters (36 to 54 inches); very pale brown (10YR 8/3) coarse sand, light yellowish brown (10YR 6/4) moist; single grain; loose, nonsticky and nonplastic; few fine interstitial pores; 75 percent coarse and very coarse, distinct, very pale brown (10YR 8/2), irregular, soft carbonate masses throughout matrix; 10 percent fine gravel; violently effervescent; strongly alkaline (pH 8.7); gradual wavy boundary.

C -- 137 to 152 centimeters (54 to 60 inches); very pale brown (10YR 7/4) coarse sand, yellowish brown (10YR 5/4) moist; single grain; loose, nonsticky and nonplastic; few fine interstitial pores; 5 percent fine gravel; strongly effervescent; strongly alkaline (pH 8.6).

TYPE LOCATION: San Bernardino County, California; approximately 12.7 kilometers (8 miles) northwest of the town of Twentynine Palms and approximately 2.2 kilometers (1.3 miles) northwest of the junction of Giant Rock and Lear Roads; 440 meters (1,143 feet) south and 800 meters (2,624 feet) west of the NE corner of section 32, T. 2 N., R. 8 E., San Bernardino Base and Meridian; 34 degrees, 13 minutes and 05.9 seconds north latitude and 116 degrees, 10 minutes and 04.3 seconds west longitude; USGS Sunfair, California 7.5 minute topographic quadrangle; UTM 11S 0576650e 3786676n (DATUM: 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 convection storms. The soils have a
typic-aridic soil moisture regime.

Soil temperature: 22 to 25 degrees C (72 to 77 F).
Surface rock fragments: 25 to 75 percent; with 15 to 45 percent fine gravel,
10 to 35 percent medium and coarse gravel and 0 to 20 percent cobbles.

Control section -
Clay content: averages 10 to 18 percent.
Rock fragments: 2 to 20 percent, dominantly gravel.
Organic matter: 0 to 0.5 percent.
Depth to the upper boundary of an argillic horizon: 25 to 50 centimeters (10
to 19 inches).
Depth to the upper boundary of a calcic horizon: 25 to 45 centimeters (10 to
18 inches).

A horizon
Hue: 10YR or 2.5Y.
Value: 6 or 7 dry, and 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Texture of the fine earth: loamy sand, loamy fine sand, or sandy loam.
Clay content: 2 to 12 percent.
Rock fragments: 3 to 30 percent, with 3 to 25 percent gravel and 0 to 5
percent cobbles.
Effervescence: noneffervescent to violently effervescent.
Reaction: neutral to moderately alkaline.
Salinity: 0 to 2 dS/m.

Bk, Bw or C horizons
Hue: 7.5YR, 10YR or 2.5Y.
Value: 5 to 7, dry and 4 or 5, moist.
Chroma: 3 or 4, dry and 3 to 6, moist.
Texture of the fine earth: coarse sand, sand, loamy coarse sand, or loamy
sand.
Clay content: 2 to 6 percent.
Rock fragments: 2 to 30 percent, with 2 to 30 percent gravel and 0 to 5
percent cobbles.
Effervescence: noneffervescent to strongly effervescent.
Reaction: slightly or moderately alkaline.
Salinity: 0 to 2 dS/m.

(2)Bt or (2)Btk horizons
Hue: 7.5YR or 10YR.
Value: 5 to 7, dry and 4 to 6, moist.
Chroma: 3 to 6, dry and 4 to 6, moist.
Texture of the fine earth: coarse sandy loam, sandy loam or sandy clay
loam.
Clay content: ranges from 8 to 23 percent, averages 10 to 18 percent.
Rock fragments: 3 to 20 percent gravel.
Calcium carbonate equivalent: 1 to 20 percent.
Reaction: slightly to very strongly alkaline.
Salinity: 0 to 4 dS/m.

B'k, 2Bk or (2)Ck horizons
Hue: 7.5YR or 10YR.
Value: 6 to 8, dry and 4 to 8, moist.
Chroma: 2 to 6, dry and 3 to 6, moist.
Texture of the fine earth: coarse sand, sand, loamy coarse sand, loamy
sand or sandy loam.
Clay content: 4 to 15 percent.
Rock fragments: 3 to 10 percent gravel.
Calcium carbonate equivalent: 1 to 45 percent.
Reaction: slightly to strongly alkaline.
Salinity: 0 to 4 dS/m.

COMPETING SERIES: These are the Catfishbay (CA), Growler (AZ) and Wellton (AZ) series. Catfishbay and Wellton soils have a depth to the upper boundary of an argillic horizon of less than 25 centimeters. Growler soils have electrical conductivities (EC) in the 4 to 70 dS/m range below 25 centimeters (10 inches). In addition, Catfishbay soils have a soil moisture control section that is usually dry and is only moist in some part for short periods during winter and early spring and a mean annual soil temperature of 25 to 28 degrees C. Growler and Wellton soils have a soil moisture control section that is moist for more than 20 days, cumulative, from July to September.

GEOGRAPHIC SETTING: Sunmill soils are on fan remnants and fan aprons over fan remnants. Slopes range from 1 to 8 percent. These soils formed in alluvium from igneous rock. Elevations range from 300 to 790 meters (984 to 2,590 feet). The climate is arid, with hot, dry summers and warm, moist winters. The mean annual precipitation is 75 to 125 millimeters (3 to 5 inches) and the mean annual air temperature is 20 to 23 degrees C (68 to 73.5 degrees F). The frost-free season is 300 to 340 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dateshake (T CA), Joetree, Patscamp, Pearlspring (T CA) and Pintobasin soils. Dateshake, Joetree, Patscamp and Pearlspring soils are on similar landscape positions. Dateshake and Joetree soils have at least 50 centimeters of sands or loamy sands over an argillic horizon. In addition, Joetree soils do not have a calcic horizon. Patscamp soils have an argillic horizon with a fine-loamy particle-size control section. Pearlspring soils have a calcic horizon but do not have an argillic horizon. Pintobasin soils are on alluvial fans, fan aprons and in drainageways, have sandy particle-size control sections and do not have an argillic or calcic horizon.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; very low to medium runoff; high saturated hydraulic conductivity above and below the argillic horizon and moderately high or high saturated hydraulic conductivity within the argillic horizon.

USE AND VEGETATION: Sunmill soils are used for rangeland, wildlife habitat and urban land. The present vegetation is mainly creosote bush and burrobush.

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

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

SERIES ESTABLISHED: San Bernardino County, California, Soil Survey of Joshua Tree National Park, California, C2012. The name is from a local feature in the soil survey area.

REMARKS: Bk and Bw horizons occurring directly below the surface horizon do not meet the necessary criteria to be considered diagnostic cambic or calcic horizons. Diagnostic horizons and features in this pedon include:

Ochric epipedon - from a depth of 0 to 4 centimeters (A horizon).
Argillic horizon - from a depth of 26 to 78 centimeters (Btk1 and Btk2
horizons).
Calcic horizon - from a depth of 44 to 137 centimeters (Btk2, B'k1 and B'k2
horizons).
Particle-size control section - 26 to 78 centimeters (Btk1 and Btk2 horizons).

ADDITIONAL DATA: NASIS User PEDON ID: TMC2522410.

Responsibility for this series was transferred from Davis to Phoenix 12/2015. The last revision to the series was 1/2012. ET

National Cooperative Soil Survey
U.S.A.