LOCATION MOKAAC AZ
Established Series
Rev. AAD/DEW/PDC
11/2015
MOKAAC SERIES
The Mokaac series consists of very deep, excessively drained soils that formed in mixed alluvium and colluvium derived from sedimentary formations high in gypsum and calcium carbonate. Mokaac soils are on fan terraces and have slopes of 2 to 20 percent. The mean annual precipitation is about 10 inches and the mean annual air temperature is about 64 degrees F.
TAXONOMIC CLASS: Sandy-skeletal, gypsic, thermic Typic Calcigypsids
TYPICAL PEDON: Mokaac very cobbly loamy fine sand - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; light brown (7.5YR 6/4) very cobbly loamy fine sand, strong brown (7.5YR 5/6) moist; weak thin platy structure; soft, very friable, nonsticky and nonplastic; many very fine and few fine roots; many very fine vesicular and few fine tubular pores; 15 percent gravel, 15 percent cobble and 5 percent stones; violently effervescent, 8 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); clear smooth boundary. (1 to 3 inches thick)
Bky--3 to 10 inches; light brown (7.5YR 6/4) gravelly loamy fine sand, strong brown (7.5YR 5/6) moist; massive; soft, very friable, nonsticky and nonplastic; many very fine and common fine roots; common fine and very fine tubular pores; 20 percent gravel and 10 percent cobble; violently effervescent with calcium carbonate segregated as common fine seams and pendants on rock fragments, 25 percent calcium carbonate equivalent; 5 percent crystalline gypsum; moderately alkaline (pH 8.4); abrupt smooth boundary. (6 to 18 inches thick)
By1--10 to 26 inches; light brown (7.5YR 6/4) extremely gravelly sand, strong brown (7.5YR 5/6) moist; single grained; loose; many very fine, common fine and few medium roots; many fine very fine irregular pores; 55 percent gravel and 5 percent cobble; violently effervescent 30 percent calcium carbonate equivalent; 30 percent crystalline gypsum, common gypsum pendants on rock fragments; slightly alkaline (pH 7.8); abrupt smooth boundary. (10 to 20 inches thick)
By2--26 to 32 inches; light brown (7.5YR 6/4) loamy fine sand, strong brown (7.5YR 5/6) moist; massive; soft, very friable, nonsticky and nonplastic; common fine and very fine roots; common fine and very fine tubular pores; 10 percent gravel; violently effervescent, 15 percent calcium carbonate equivalent; 10 percent crystalline gypsum, common gypsum pendants on rock fragments; slightly alkaline (pH 7.8); abrupt smooth boundary. (4 to 8 inches thick)
By3--32 to 41 inches; light brown (7.5YR 6/4) very gravelly loamy coarse sand, brown (7.5YR 4/4) moist; single grained; loose; common fine and very fine roots; many fine and very fine irregular pores; 50 percent gravel; violently effervescent, 24 percent calcium carbonate equivalent; 30 percent crystalline gypsum, common gypsum pendants on rock fragments; slightly alkaline (pH 7.8); abrupt smooth boundary. (6 to 12 inches thick)
2Bkb1--41 to 52 inches; reddish yellow (5YR 6/6) loam, yellowish red (5YR 4/6) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and very fine roots; common fine and very fine tubular and interstitial pores; 5 percent gravel; violently effervescent with calcium carbonate segregated as common fine seams, 20 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); abrupt smooth boundary. (0 to 12 inches thick)
2Bkb2--52 to 60 inches; red (2.5YR 5/6) clay loam, red (2.5YR 4/6) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky and plastic; no roots; common fine and very fine tubular and interstitial pores; 10 percent gravel; violently effervescent with calcium carbonate segregated as common medium seams and soft masses, 20 percent calcium carbonate equivalent; moderately alkaline (pH 8.0)
TYPE LOCATION: Mohave County, Arizona; about 3.5 miles south of the Arizona-Utah state line and 1 mile west of Hurricane Cliffs; 1500 feet north and 1800 feet east of the southwest corner of section 14, T.41 N., R.10 W.; Latitude 36 degrees 57 minutes 06 seconds N, Longitude 113 degrees 20 minutes 50 seconds W.
RANGE IN CHARACTERISTICS:
Soil Moisture: Intermittently moist in some part of the soil moisture control section during July - September and December - February. Driest during May and June. Typic aridic soil moisture regime.
Percent gypsum x centimeters thickness = less than 3000
Percent gypsum plus calcium carbonate = greater than 40 percent
Rock Fragments: averages 35 to 60 percent gravel, cobble, and stones
Soil Temperature: 59 to 72 degrees F.
Depth to Calcic horizon: 1 to 3 inches
Depth to Gypsic horizon: 15 to 35 inches
A horizon
Hue: 5YR, 7.5YR
Value: 5 through 7 dry, 4 or 5 moist
Chroma: 4 through 6, dry or moist
Bk or Bky horizons
Hue: 5YR, 7.5YR
Value: 5 through 7 dry, 4 through 6 moist
Chroma: 4 through 6, dry or moist
Texture: loamy fine sand, fine sandy loam, sandy loam
Calcium carbonate equivalent: 10 to 35 percent
Gypsum: less than 10 percent
By horizon
Hue: 5YR, 7.5YR
Value: 5 through 7 dry, 4 through 6 moist
Chroma: 4 through 6, dry or moist
Texture: sand, loamy sand, loamy coarse sand, coarse sand
Calcium carbonate equivalent: 10 to 35 percent
Gypsum: 15 to 50 percent
The buried horizon may not be present in all pedons.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Mokaac soils are on fan terraces and have slopes of 2 to 20 percent. These soils formed in mixed alluvium and colluvium derived from sedimentary formations high in gypsum and calcium carbonate. Elevation ranges from 1600 to 4500 feet. Mean annual precipitation ranges from 8 to 12 inches. The mean annual air temperature is 57 to 70 degrees F. The frost-free period is 180 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Akinville,
Gypill and
Ruesh series. Gypill soils have a lithic contact at depths less than 20 inches. Ruesh soils are coarse-loamy. Akinville soils are sandy-skeletal.
DRAINAGE AND PERMEABILITY: Excessively drained; slow to rapid runoff; rapid permeability. Flooding is none to rare.
USE AND VEGETATION: Mokaac soils are used for livestock grazing and wildlife habitat. The present vegetation is creosotebush, gyp dropseed, big galleta and fluffgrass.
DISTRIBUTION AND EXTENT: Northwestern Arizona. The series is of small extent. MLRA is 30.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: PHOENIX, ARIZONA
SERIES ESTABLISHED: Mohave County, Arizona; Soil survey of Shivwits Area, Arizona, Part of Mohave County; 1994.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 3 inches (A horizon)
Calcic horizon - The zone from 3 to 10 inches (Bky horizon)
Gypsic horizon - The zone from 10 to 41 inches (By1, By2, By3 horizons)
Formerly classified as Calcic Gypsiorthids.
ADDITIONAL DATA: NSSL Reference sample S89AZ - 015 -3
Responsibility for this series was transferred from Davis to Phoenix 11/2015. The last revision to the series was 5/1997. ET
National Cooperative Soil Survey
U.S.A.