LOCATION GROTTOHILL              CA

Tentative Series
SMR/GMW/EEM/LJL/ET
04/2015

GROTTOHILL SERIES

The Grottohill series consists of very deep, well drained soils that formed in alluvium derived from granitoid. The Grottohill soils are on fan remnants and fan aprons. Slopes range from 1 to 8 percent. The mean annual precipitation is about 200 millimeters (8 inches) and the mean annual air temperature is about 15 degrees C (59 degrees F).

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Ustic Haplocambids

TYPICAL PEDON: Grottohill sandy loam, on a 3 percent slope at an elevation of 1,364 meters (4,480 feet). (Colors are for dry soils unless otherwise noted.) The soil surface is covered by 12 percent fine gravel and 6 percent medium and coarse gravel.

A1 -- 0 to 3 centimeters (0 to 1 inches); brown (10YR 5/3) sandy loam, brown (10YR 4/3) moist; moderate thick platy structure; soft, very friable, slightly sticky and nonplastic; common very fine roots throughout; common very fine irregular pores; 4 percent fine gravel and 1 percent medium and coarse gravel; neutral (pH 6.8); abrupt smooth boundary.

A2 -- 3 to 9 centimeters (1 to 4 inches); brown (10YR 5/3) sandy loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; common very fine roots throughout; common fine irregular and common very fine dendritic tubular pores; 5 percent fine gravel and 2 percent medium and coarse gravel; neutral (pH 6.7); abrupt smooth boundary. (Combined thickness of A horizons is 3 to 10 centimeters, 1 to 4 inches.)

Bw -- 9 to 56 centimeters (4 to 22 inches); brown (7.5YR 5/4) sandy loam, dark yellowish brown (10YR 4/4) moist; moderate coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots throughout; common very fine irregular and dendritic tubular pores; 4 percent fine gravel and 1 percent medium and coarse gravel; slightly alkaline (pH 7.5); clear smooth boundary. (12 to 53 centimeters 5 to 21 inches thick)

Bk -- 56 to 90 centimeters (22 to 35 inches); yellowish brown (10YR 5/4) sandy loam, brown (10YR 4/3) moist; moderate coarse subangular blocky structure; moderately hard, very friable, slightly sticky and slightly plastic; common very fine roots throughout; common very fine irregular and dendritic tubular pores; 1 percent fine prominent spherical white (10YR 8/1), dry, calcium carbonate masses with sharp boundaries in matrix; 4 percent fine gravel and 1 percent medium and coarse gravel; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary.

Btk -- 90 to 115 centimeters (35 to 45 inches); brown (7.5YR 5/4) sandy loam, brown (7.5YR 4/4) moist; massive; moderately hard, very friable, nonsticky and nonplastic; few very fine, fine, and medium roots throughout; common very fine irregular and dendritic tubular and common medium tubular pores; 2 percent faint yellowish brown (10YR 5/4), dry, clay bridges between sand grains; 2 percent medium prominent irregular very weakly cemented very pale brown (10YR 8/2), dry, calcium carbonate nodules with sharp boundaries in matrix; 6 percent fine gravel and 2 percent medium and coarse gravel; slightly effervescent; strongly alkaline (pH 8.5); clear wavy boundary.

B'k -- 115 to 152 centimeters (45 to 60 inches); brown (7.5YR 5/4) gravelly sandy loam, brown (7.5YR 4/4) moist; massive; moderately hard, very friable, slightly sticky and nonplastic; few very fine roots throughout; few fine and common very fine interstitial pores; 10 percent distinct white (10YR 8/1), dry, calcium carbonate coats on bottom surfaces of rock fragments and 2 percent medium prominent irregular very weakly cemented very pale brown (10YR 8/2), dry, calcium carbonate nodules with sharp boundaries in matrix; 10 percent fine gravel, 10 percent medium and coarse gravel and 2 percent cobbles; strongly effervescent; moderately alkaline (pH 8.3); abrupt wavy boundary. (Combined thickness of Bk and Btk horizons is 40 to 113 centimeters, 16 to 44 inches.)

2C -- 152 to 170 centimeters (60 to 67 inches); brown (7.5YR 5/4) very gravelly coarse sand, brown (7.5YR 5/4) moist; single grain; loose, nonsticky and nonplastic; few very fine roots throughout; common very fine, fine and medium interstitial pores; 30 percent fine gravel, 20 percent medium and coarse gravel and 2 percent cobbles; slightly effervescent; strongly alkaline (pH 8.5).

TYPE LOCATION: San Bernardino County, California; approximately 34 kilometers (21 miles) south of the town of Nipton, California; approximately 6.5 kilometers (4 miles) northwest of the intersection of Ivanpah Road and Cedar Canyon Road; 430 meters (1,410 feet) east and 325 meters (1,065 feet) south of the north west corner of sec. 35 N., T. 13, R. 16 E.; San Bernardino Base and Meridian; USGS Grotto Hills, CA 7.5 minute topographic quadrangle; 35 degrees, 10 minutes, 6.6 seconds north latitude and 115 degrees, 14 minutes, 1.3 seconds west longitude; UTM 11S 660856e 3893157n; (DATUM: NAD83).

RANGE IN CHARACTERISTICS:

Soil moisture control section: usually dry, moist in some part from December to March and intermittently moist for 10 to 20 days during July to September following summer convection storms; aridic bordering on ustic soil moisture regime.

Soil temperature: 15 to 19 degrees C. (59 to 66 degrees F.)
Depth to cambic horizon: 5 to 19 centimeters (2 to 7 inches).
Depth to secondary carbonates: 15 to 60 centimeters (6 to 24 inches).
Surface rock fragments: 15 to 35 percent gravel.

Control section
Clay content: 7 to 14 percent.
Rock fragments: 5 to 15 percent, dominantly gravel.

A horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry and moist.
Clay content: 5 to 9 percent.
Rock fragments: 5 to 14 percent dominantly fine gravels.
Reaction: slightly acid to slightly alkaline.

Bw horizon
Hue: 7.5YR or 10YR.
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 3 or 4 dry, 3 to 6 moist.
Texture: sandy loam or fine sandy loam.
Clay content: 6 to 12 percent.
Rock fragments: 5 to 12 percent dominantly fine gravel, 0 to 2 percent cobbles.
Reaction: neutral to slightly alkaline.

Bk and/or Btk horizons
Hue: 7.5YR or 10YR.
Value: 4 to 6 dry, 3 to 5 moist.
Chroma: 3 to 6 dry, 3 or 4 moist.
Texture: loamy sand, coarse sandy loam, sandy loam or fine sandy loam.
Clay content: 7 to 14 percent.
Rock fragments: 5 to 20 percent dominantly fine gravel, 0 to 2 percent cobbles.
Effervescence: noneffervescent to violently effervescent.
Calcium carbonate equivalence of the fine earth: 0 to 3 percent.
Reaction: neutral to strongly alkaline.

C(k,q)horizon
Hue: 7.5YR or 10YR.
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 3 or 4, dry and moist.
Texture: coarse sand, sandy loam, and fine sandy loam.
Clay content: 2 to 14 percent.
Rock fragments: 6 to 50 percent dominantly fine gravel, 0 to 2 percent cobbles.
Effervescence: neutral to strongly effervescent.
Calcium carbonate equivalence of the fine earth: 0 to 3 percent.
Reaction: neutral to strongly alkaline.

COMPETING SERIES: These are the Ima (NM+TX), Mallet (AZ) and Perilla (AZ) series. Ima soils are dry in the soil moisture control section from October to May and are formed from sandstone and shale. Mallet and Perilla soils receive significantly larger amounts of precipitation characteristic of the Sonoran Desert (300 to 400 millimeters, 12 to 16 inches of precipitation). Mallet soils also do not have accumulation of secondary carbonates above 75 centimeters (30 inches) and have greater than 1 percent organic matter in the particle size control section.

GEOGRAPHIC SETTING: The Grottohill soils are on fan remnants and fan aprons. Slopes range from 1 to 8 percent. These soils formed in alluvium from granitoid sources. Elevation is 1,340 to 1,585 meters (4,395 to 5,200 feet). The climate is arid with cool, moist winters and warm, intermittently moist summers. The mean annual precipitation is 175 to 225 millimeters (7 to 9 inches) and the mean annual air temperature is 13 to 17 degrees C. (56 to 62 F.) The frost free season is 210 to 270 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Rosshorse (T CA), Sagamore (T CA) and Stonekey (T CA) soils. Rosshorse soils have a calcic horizon. Sagamore soils are very shallow and shallow to a petrocalcic horizon. Stonekey soils are moderately deep to a petocalcic horizon.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high saturated hydraulic conductivity.

USE AND VEGETATION: These soils are used for recreation and wildlife habitat. The present vegetation is big galleta, black grama, Joshua tree and Cooper's goldenbush.

DISTRIBUTION AND EXTENT: Mojave Desert of southeastern California, U.S.A.; MLRA 30. These soils are of small extent.

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

SERIES PROPOSED: San Bernardino County, California; Soil Survey of Mojave National Preserve Area, California, 2012. The name is coined.

REMARKS: Diagnostic horizons and features in this pedon include:

Ochric epipedon - from a depth of 0 to 18 centimeters (0 to 7 inches) (A1 and A2 horizon).
Cambic horizon - from a depth of 9 to 152 centimeters (4 to 60 inches) (Bw, Bk, Btk and Bk' horizons).
Particle-size control section - from a depth of 25 to 100 centimeters (10 to 39 inches) (Bw, Bk and Btk horizons).

ADDITIONAL DATA: NASIS User Pedon ID: 11CA795054.

Responsibility for this series was transferred from Davis to Phoenix 4/2015. The last revision to the series was 10/2012. ET

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National Cooperative Soil Survey
U.S.A.