LOCATION TWIST AZEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Calcic Argigypsids
TYPICAL PEDON: Twist loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; light reddish brown (5YR 6/4) loam, reddish brown (5YR 4/4) moist; weak thin platy structure; slightly hard, friable, slightly sticky and nonplastic; many very fine vesicular and few fine tubular pores; 5 percent fine gravel; very slightly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (1 to 2 inches thick)
Bt--2 to 7 inches; yellowish red (5YR 5/6) loam, yellowish red (5YR 4/6) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots; common fine and very fine tubular and interstitial pores; few faint clay films on faces of peds and lining pores; 5 percent gravel; slightly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (4 to 6 inches thick)
Btk--7 to 15 inches; reddish yellow (5YR 6/6) clay loam, yellowish red (5YR 4/6) moist; moderate medium subangular blocky structure; hard, friable, sticky and slightly plastic; many fine and very fine roots; common fine and very fine tubular and interstitial pores; common faint clay films on faces of peds and lining pores; 5 percent fine gravel; strongly effervescent, calcium carbonate segregated in many fine seams and soft masses, 18 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); clear smooth boundary. (7 to 10 inches thick)
Bk--15 to 37 inches; reddish yellow (5YR 7/6) and pink (5YR 8/3) sandy clay loam, yellowish red (5YR 5/6) and pink (5YR 7/3) moist; strong medium subangular blocky structure; very hard, firm, sticky and slightly plastic; many very fine and common fine roots; common fine and very fine tubular and interstitial pores; violently effervescent, weakly cemented with calcium carbonate, 60 percent calcium carbonate equivalent; strongly alkaline (pH 8.6); abrupt wavy boundary. (15 to 25 inches thick)
2Bky--37 to 53 inches; reddish yellow (5YR 7/6) sandy loam, reddish yellow (5YR 6/6) moist; massive; very hard, firm, nonsticky and nonplastic; common very fine and few fine roots; common fine and very fine tubular and irregular pores; strongly effervescent, calcium carbonate segregated as common soft masses and seams, 28 percent calcium carbonate equivalent; 5 percent crystalline gypsum; moderately alkaline (pH 8.0); clear wavy boundary. (10 to 18 inches thick)
2By1--53 to 58 inches; reddish yellow (5YR 7/6) sandy loam, reddish yellow (5YR 6/6) moist; massive; hard, friable, nonsticky and nonplastic; no observed roots; common fine and very fine tubular and irregular pores; noneffervescent; 30 percent crystalline gypsum; slightly alkaline (pH 7.8); smooth boundary. (4 to 8 inches thick)
2By2--58 to 60 inches; white (N8/) gypsum, white (N8/) moist; massive; hard, firm, nonsticky and nonplastic; noneffervescent; 70 to 80 percent crystalline gypsum; slightly alkaline (pH 7.8).
TYPE LOCATION: Mohave County, Arizona; about 17 miles south of the AZ/UT state line and 55 miles west of Hurricane Cliffs; 700 feet north and 1000 feet west of the southeast corner of section 20, T. 39 N., R. 10 W.; 36 degrees, 45 minutes, 45 seconds north latitude and 113 degrees, 23 minutes, 11 seconds west longitude.
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.
Rock fragments: less than 15 percent
Soil temperature: 56 to 61 degrees F.
Organic matter: less than 1 percent
Depth to base of argillic: 15 to 20 inches
Depth to calcic: 15 to 20 inches
Depth to gypsic: 30 to 39 inches
A horizon
Hue: 5YR, 7.5YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 3 to 6, dry or moist
Calcium carbonate equivalent: 1 to 15 percent
Bt and Btk horizon
Hue: 5YR, 7.5YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 4 to 6, dry or moist
Texture: clay loam, loam, sandy clay loam
Calcium carbonate equivalent: 1 to 20 percent
Bk horizon
Hue: 5YR, 7.5YR
Value: 6 to 8 dry, 5 to 8 moist
Chroma: 2 to 6, dry or moist
Texture: loam, sandy loam
Reaction: moderately or strongly alkaline
Calcium carbonate equivalent: 15 to 60 percent; can be weakly cemented
By horizon
Value: 6 to 8, dry or moist
Chroma: 0 to 6, dry or moist
Texture: gypsum with texture similar to sandy loam
Gypsum content: 5 to 80 percent
Calcium carbonate equivalent: 1 to 30 percent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Twist soils are on fan remnant and stream terraces and have 1 to 10 percent slopes. These soils formed in mixed alluvium derived dominantly from sedimentary formations dominated by limestone and gypsiferous shale. Elevations range from 4000 to 5000 feet. Mean annual precipitation is 7 to 11 inches. The mean annual air temperature is 54 to 59 degrees F. The frost-free period is 165 to 195 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Goblin, Robroost and Moenkopie soils. These soils do not have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately slow permeability.
USE AND VEGETATION: Twist soils are used for livestock grazing and wildlife habitat. The present vegetation is galleta, black grama, Mormon-tea and bottlebrush squirreltail.
DISTRIBUTION AND EXTENT: Northern Arizona. This series is of small extent. MLRA is 35.
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 2 inches (A horizon)
Argillic horizon - The zone from 2 to 15 inches (Bt, Btk horizons)
Calcic horizon - The zone from 17 to 53 inches (Btk, Bk, 2Bky horizons)
Gypsic horizon - The zone from 37 to 60 inches (2Bky, 2By1, 2By2 horizons)
Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy Tenth Edition, 2006.
Formerly classified as Typic Haplargids.