LOCATION MEXTANK AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Aridic Calciustolls
TYPICAL PEDON: Mextank extremely gravelly fine sandy loam - woodland. (Colors are for dry soil unless otherwise noted).
A--0 to 1 inch; brown (7.5YR 5/3) extremely gravelly fine sandy loam, dark brown (7.5YR 3/2) moist; moderate thick platy structure; slightly hard, very friable, nonsticky and nonplastic; many very fine roots; common very fine tubular and irregular pores; violently effervescent; 90 percent gravel as surface; slightly alkaline (pH 7.7); abrupt smooth boundary. (1 to 5 inches thick)
BA--1 to 5 inches; brown (7.5YR 5/3) very gravelly fine sandy loam, dark brown (7.5YR 3/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; many very fine tubular and common very fine irregular pores; violently effervescent; 35 percent gravel; slightly alkaline (pH 7.8); abrupt smooth boundary. (0 to 7 inches thick)
Bk1--5 to 14 inches; brown (7.5YR 5/3) very gravelly loam, dark brown (7.5YR 3/3) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine, many fine, and few medium and coarse roots; common very fine irregular pores; common faint calcium carbonate coatings and thin pendants on rock fragments; violently effervescent; 40 percent gravel; slightly alkaline (pH 7.8); abrupt smooth boundary. (8 to 10 inches thick)
Bk2--14 to 27 inches; brown (7.5YR 5/2) very cobbly loam, brown (7.5YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common fine and medium, few very fine and coarse roots; common fine tubular and common very fine irregular pores; common faint calcium carbonate coatings and many pendants on rock fragments; violently effervescent; 5 percent stones, 25 percent cobble, and 20 percent gravel; moderately alkaline (pH 8.0); abrupt smooth boundary. (10 to 15 inches thick)
Bk3--27 to 36 inches; brown (7.5YR 5/4) very gravelly loam, brown (7.5YR 4/4) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; few very fine and fine and common medium roots; common very fine irregular and few fine tubular pores; common faint calcium carbonate coatings and many pendants on rock fragments; violently effervescent; 50 percent gravel; moderately alkaline (pH 8.0); clear smooth boundary. (8 to 10 inches thick)
Bk4--36 to 50 inches; brown (7.5YR 5/4) very gravelly sandy clay loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few fine and medium roots; common very fine irregular pores; few faint clay films on ped faces; common faint calcium carbonate coatings and many pendants on rock fragment;; violently effervescent; 50 percent gravel; moderately alkaline (pH 8.0); abrupt smooth boundary. (12 to 18 inches thick)
2Ck--50 to 60 inches; light brown (7.5YR 6/4) extremely gravelly coarse sandy loam, strong brown (7.5YR 4/6) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few fine and medium roots; common very fine and fine irregular pores; common faint calcium carbonate coatings and many pendants on rock fragments; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Coconino County, Arizona; on the Hualapai Indian Reservation; 2200 feet west and 2300 feet north of the southeast corner of section 34, T.20 N., R.8 W.
RANGE IN CHARACTERISTICS:
Soil moisture: Moist in some part of the soil moisture control section during December - March and July - September. Approximately 60 percent of the annual precipitation occurs during the winter months. Driest during May and June. Aridic ustic soil moisture regime.
Soil Temperature: 54 to 56 degrees F.
Thickness of mollic epipedon: 10 to 20 inches
Depth to calcic horizon: 1 to 20 inches
Clay content: ranges from 12 to 22 percent, averages less than 18 percent in the control section
Rock fragments: 35 to 60 percent in the control section. Below the control section, rock fragments may range up to 75 percent.
A horizon
Hue: 10YR, 7.5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist
Bk horizons
Hue: 10YR, 7.5YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 through 4, dry or moist
Texture: fine sandy loam, sandy loam, sandy clay loam
Calcium carbonate equivalent: 5 to 30 percent
2Ck horizon
Hue: 10YR, 7.5YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 4 through 6, dry or moist
Texture: Stratified coarse sandy loam, sandy loam, loam, sandy clay loam
Rock fragments: 35 to 75 percent
COMPETING SERIES: These are the Ayon (NM), Curabith (CO), Hogadero (NM), Hubert (AZ), Modyon (NM), and Pena (NM) series. Ayon soils averages more than 18 percent clay and is dominated by stone and cobble. Curabith soils have mean annual soil temperature of 49 to 52 degrees F., and have mollic surface layers of 7 to 10 inches. Hogadero soils have strongly cemented calcic horizons. Modyon soils are moderately deep to bedrock. Hubert and Pena soils do not have lithologic discontinuities in the lower pedon containing stratified materials.
GEOGRAPHIC SETTING: Mextank soils are on alluvial fans and fan terraces at elevations of 5000 to 6500 feet. These soils formed in alluvium and colluvium from sandstone and limestone. Slopes range from 2 to 20 percent. The mean annual air temperature is 52 to 54 degrees F. The mean annual precipitation is 14 to 18 inches. The frost-free period is 135 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lykorly and Disterheff series. Lykorly soils are fine-loamy and Disterheff series are fine textured.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Mextank soils are used for fuelwood production, grazeable woodland, and wildlife habitat. The present vegetation is Utah juniper, Colorado pinyon, bottle brush squirreltail, blue grama, muttongrass, turbinella oak, Wyoming big sagebrush, and Wright birdbeak.
DISTRIBUTION AND EXTENT: Northern Arizona. This series is not extensive. MLRA is 38 and 39.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Coconino County, Arizona; Soil survey of the Hualapai-Havasupai Area, AZ, Parts of Coconino, Mohave, and Yavapai Counties; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 14 inches (A, BA, Bk1 horizons)
Calcic horizon - The zone from 5 to 50 inches (Bk1, Bk2, Bk3, Bk4 horizons)
Classified according to Keys to Soil Taxonomy Ninth Edition, 2003.