LOCATION GRAN AZEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, thermic, shallow Typic Haplargids
TYPICAL PEDON: Gran very gravelly sandy loam-rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 1 inch; reddish yellow (7.5YR 6/6) very gravelly sandy loam, brown (7.5YR 4/4) moist; weak thin platy structure; slightly hard, friable, nonsticky and nonplastic; many fine roots; common very fine vesicular pores; 55 percent gravel; noneffervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (1 to 4 inches thick)
Bt--1 to 12 inches; light red (2.5YR 6/8) extremely gravelly coarse sandy clay, red (2.5YR 5/8) moist; moderate medium prismatic structure parting to strong medium angular blocky, hard, friable, very sticky and very plastic; common very fine roots; few very fine tubular pores; many moderately thick clay films on faces of peds; common pressure faces; 85 percent gravel; noneffervescent; moderately alkaline (pH 8.0); gradual irregular boundary. (7 to 16 inches thick)
2Crt--12 to 36 inches; partially weathered granitic rock (grus), few very fine roots; common thin clay films coating bedrock and in fractures; gradual irregular boundary. (12 to 24 inches thick)
2R--36 inches; granitic rock.
TYPE LOCATION: Maricopa County, Arizona; one mile south of Dynamite Boulevard in the NW corner of McDowell Regional Park; 900 feet south and 50 feet east of the NW corner of section 6, T. 4 N., R. 6 E. Latitude of 33 degrees, 43 minutes, 27 seconds N., Longitude of 111 degrees, 47 minutes, 14 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture - Intermittently moist in some part of the SMCS during July-September and December-February. Typic aridic soil moisture regime.
Rock fragments: greater than 35 percent by volume in the control section
Depth to paralithic contact: 8 to 20 inches
Depth to bedrock: 20 to 40 inches
Carbonates: noneffervescent
A horizon
Hue: 10YR, 7.5YR, 5YR
Value: 4 to 7 dry, 3 to 7 moist
Chroma: 4 to 8 dry, 3 to 6 moist
Texture: sandy loam, loam, clay loam, sandy clay loam
Clay content: 5 to 30 percent
Organic matter: less than 1 percent
Reaction: neutral to moderately alkaline
B horizon
Hue: 2.5YR, 5YR
Value: 4 to 6 dry, 3 to 5 dry
Chroma: 3 to 8, dry or moist
Texture: clay loam, sandy clay, clay
Clay content: 35 to 50 percent clay
Reaction: slightly acid to moderately alkaline
COMPETING SERIES: This is the Granolite (AZ)series. The Granolite soils formed in slope alluvium derived from volcanic and metamorphic rock and have accumulations of calcium carbonate.
GEOGRAPHIC SETTING: Gran soils are on pediments, hillslopes and mountain slopes and have gradients of 1 to 65 percent. They formed in alluvium-colluvium weathered from granite and to some extent from rhyolite, andesite, latite and diorite. Elevation is 1,800 to 4,000 feet. The climate is warm and semi-arid continental. Average annual precipitation is 8 to 12 inches occurring as summer thunderstorms and gentle winter rain. Mean annual temperature is 66 to 70 degrees F. Frost-free period is about 220 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dixaleta and Wickenburg soils. Dixaleta and Wickenburg soils lack argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately slow permeability.
USE AND VEGETATION: Used for livestock grazing. The native vegetation is brittlebush, creosotebush, cholla, ironwood, paloverde, mesquite, jojoba, catclaw, triangle bursage, yucca, barrel cactus, saguaro cactus, ocotillo, and graythorn.
DISTRIBUTION AND EXTENT: South Central Arizona. The series is moderately extensive. MLRA is 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Maricopa County, Arizona, 1982.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: the zone from 0 to 1 inch (A horizon)
Argillic horizon: the zone from 1 to 12 inches (Bt horizon)
Paralithic contact: the boundary at 12 inches (2Crt horizon)
Lithic contact: the boundary at 36 inches (2R horizon)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.
Revised for the correlation of AZ661, 2/2009, WWJ