LOCATION CUROB AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic, shallow Typic Petrocalcids
TYPICAL PEDON: Curob very gravelly loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; light brown (7.5YR 6/4) very gravelly loam, brown (7.5YR 4/4) moist; moderate thin platy structure; slightly hard, very friable; few very fine roots; common very fine tubular pores; 35 percent gravel; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (2 to 4 inches thick)
Bw1--3 to 7 inches; light brown (7.5YR 6/4) gravelly loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure parting to moderate fine granular; slightly hard, very friable; common very fine roots; many very fine tubular pores; 30 percent gravel; violently effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (4 to 12 inches thick)
Bw2--7 to 13 inches; brown (7.5YR 5/4) very gravelly loam, brown (7.5YR 4/4) moist; weak very fine subangular structure; slightly hard, very friable; many very fine roots; many very fine tubular pores; 40 percent gravel; violently effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (0 to 8 inches thick)
2Bkm--13 to 19 inches; trowelled, laminated indurated calcium carbonate cemented petrocalcic with 1/8 to 1/2 inch thick calcium carbonate pendants on the underside. (4 to 16 inches thick)
3C1--19 to 35 inches; light brown (7.5YR 6/4) extremely gravelly loamy coarse sand, brown (7.5YR 5/3) moist; massive; slightly hard, very friable; few very fine roots; many very fine tubular pores; 80 percent pebbles; discontinuous areas of indurated pan; violently effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (10 to 21 inches thick)
3C2--35 to 45 inches; light brown (7.5YR 6/4) extremely gravelly loamy coarse sand, brown (7.5YR 5/3) moist; massive; hard, very friable; few very fine roots; many fine interstitial pores; 80 percent pebbles; violently effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary. (4 to 10 inches thick)
3C3--45 to 60 inches; light brown (7.5YR 6/4) extremely gravelly loamy coarse sand, brown (7.5YR 4/4) moist; massive; slightly hard, very friable; few very fine roots; many very fine tubular pores; 60 percent pebbles, 5 percent cobble; violently effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Coconino County, Arizona; about 19 miles southwest of Marble Canyon; 1,600 feet east and 800 feet north of the southwest corner of section 15, T. 37 N., R. 4 E.
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.
Soil Temperature - 57 to 59 degrees F.
Rock Fragments - 35 to 80 percent gravel and/or cobble. Averages 35 to 65 percent in the control section
Carbonates- 15 to 40 percent calcium carbonate equivalent
Thickness of petrocalcic - 5 to 18 inches
Depth to petrocalcic - 10 to 20 inches
A horizon
Hue: 7.5YR, 5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4 dry, 4 or 6 moist
Bw horizon
Hue: 7.5YR, 5YR, 2.5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 4 or 6, dry or moist
Texture: loam, sandy loam
C horizon
Hue: 7.5YR, 5YR
Value: 6 or 7 dry, 4 to 6 moist
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Curob soils are on fan remnants. These soils formed in limestone alluvium. Slopes range from 2 to 12 percent. Elevation ranges from 3,600 to 5,200 feet. Mean annual precipitation is 7 to 11 inches that falls as summer thunderstorms and gentle winter rains and snow. Mean annual air temperature is 55 to 57 degrees F. Frost- free period is 165 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bison, Clayhole, Kinan, Monierco, Monue, Pennell, and Seeg series. Bison soils are moderately deep to a hardpan. Clayhole soils have a high content of gypsum. Kinan, Monue, and Seeg soils are very deep. Monierco and Pennell soils are shallow to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; medium or slow runoff; moderate permeability.
USE AND VEGETATION: Used mainly for livestock grazing. Vegetation is blue grama, galleta, snakeweed and fourwing saltbush.
DISTRIBUTION AND EXTENT: Northern Arizona. The Curob series is of moderate extent. MLRA 35.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Coconino County, Arizona; Soil survey of Coconino County Area, Arizona, North Kaibab Part; 1991.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 3 inches (A horizon)
Cambic horizon - The zone from 3 to 13 inches (Bw1, Bw2 horizons)
Petrocalcic horizon - The zone from 13 to 19 inches (2Bkm horizon)
Classified according to Soil Taxonomy Second Edition, 1999.