LOCATION PELONCILLO AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic, shallow Typic Argidurids
TYPICAL PEDON: Peloncillo extremely cobbly sandy clay loam-rangeland. (Colors are for dry soil unless otherwise noted.) 75 to 85 percent surface coverage composed of 50 percent cobbles, 25 percent mixed gravel, and 25 percent duripan fragments of 1 to 10 cm in diameter with rounded edges.
A--0 to 1 inch; very pale brown (10YR 7/4) extremely cobbly sandy clay loam, dark yellowish brown (10YR 4/4) moist; weak fine platy structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine vesicular and common very fine interstitial pores; 65 percent cobbles, pebbles with thin lime coatings and pebble-size duripan fragments; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (1 to 3 inches thick)
Btk1--1 to 6 inches; light brown (7.5YR 6/4) very gravelly clay loam, brown (7.5YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, sticky and slightly plastic; many fine roots; common fine tubular and interstitial pores; few thin clay films on faces of peds and in pores; 50 percent pebbles and cobbles with thin lime coatings; few very fine lime filaments and soft masses; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (2 to 6 inches thick)
Btk2--6 to 10 inches; light brown (7.5YR 6/4) very gravelly light clay loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine interstitial pores; few thin clay films on faces of peds and in pores; 60 percent pebble-size duripan fragments; common very fine and fine lime filaments and soft masses; violently effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (2 to 6 inches thick)
Btk3--10 to 15 inches; light brown (7.5YR 6/4) very gravelly light clay loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic and in pores; 50 percent pebbles-size duripan fragments; common very fine and fine lime filaments and soft masses; violently effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (2 to 5 inches thick)
2Bqm--15 to 20 inches; pink (7.5YR 8/4) dry and light brown (7.5YR 6/4) moist; indurated silica-lime cemented duripan with thin laminar surface; abrupt wavy boundary. (4 to 6 inches thick)
2Bkqm--20 to 60 inches; alternating 2 to 5 inches thick pink indurated silica-lime layers with 3 to 10 inches thick and light brown (7.5YR 6/4) very gravelly sandy loam.
TYPE LOCATION: Graham County, Arizona; approximately 18 miles east of Safford on Old Safford Road just below foot slopes of Black Hills; 1,000 feet north of the SW corner section 32, T.6S., R.29E.
RANGE IN CHARACTERISTICS:
Soil moisture: Upper 4 inches or more intermittently moist in July and August. MCS usually moist in some part in December through February. Typic aridic moisture regime.
Mean annual soil temperature: 59 degrees to 72 degrees F.
Rock fragments (particle-size control section): 35 to 85 percent cobbles and pebbles
Depth to duripan: 7 to 20 inches
A horizon
Hue: 10YR or 7.5YR
Value: 5 to 7 dry, 4 or 5 moist
Chroma: 3 or 4 dry or moist
Organic matter: Less than 1 percent
B horizon
Hue: 7.5YR or 10YR
Value: 4 or 5 dry or moist
Chroma: 3 or 4 dry or moist
Texture: c1, 1 (25 to 35 percent clay)
Carbonates: More than 15 percent calcium carbonate
Bm horizon
Below the Bqm horizon intermittent duripan layers 2 to 5 inches thick to more than 60 inches
COMPETING SERIES: These are the Dedas (NV) and Fourcorners (CA) series. Dedas soils have a thin duripan over bedrock and bedrock is at a depth of 16 to 24 inches. Fourcorners soils are moist in some part of the moisture control section for less than 20 days cumulative during July to September.
GEOGRAPHIC SETTING: Peloncillo soils are on dissected alluvial fans or fan terraces and have gradients of 1 to 30 percent. They formed in alluvium from volcanic rocks. Elevations are 3,000 to 5,000 feet. Mean annual precipitation is 8 to 12 inches. Mean annual temperature is 57 degrees to 70 degrees F. Frost-free period is 180 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Akela, Cave, Graham, House Mountain, Lehmans, Limpia, Pinaleno, Tres Hermanos and Tapco soils. Akela, Graham, House Mountain, and Lehmans soils have a lithic contact at a depth of less than 20 inches. Limpia, Pinaleno, and Tres Hermanos soils are deep. Cave soils contain less than 35 percent coarse fragments and lack an argillic horizon. Tapco soils are fine and have less than 35 percent rock fragments in the particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately slow permeability.
USE AND VEGETATION: Used for rangeland. Natural vegetation is creosotebush, ocotillo, prickly pear, cholla, poverty three-awn, bush muhly and annuals.
DISTRIBUTION AND EXTENT: Southeastern Arizona and possibly southwestern New Mexico. The soil is of moderate extent. MLRA 41.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Graham County (Gila-Duncan Area, Parts of Graham and Greenlee Counties), Arizona, 1979.
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 about 1 to 15 inches (Btk horizons).
Duripan- The zone from about 15 to 20 inches (Bqm horizon).
Pronounced Pay-loan-see-yo.
ADDITIONAL DATA: National Soil Survey Laboratory sample S77AZ-009-001 and S77AZ-009-003.