LOCATION GORDO AZEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Pachic Argiustolls
TYPICAL PEDON: Gordo silt loam - forest. (Colors are for dry soil unless otherwise noted.)
0i--0 to 1 inch; pine litter and aspen leaves.
A1--1 to 9 inches; brown (7.5YR 4/2) silt loam, dark brown (7.5YR 3/2) moist; strong fine granular structure; soft, friable, nonsticky and slightly plastic; many fine roots; many very fine interstitial pores; noneffervescent; slightly acid (pH 6.1); clear wavy boundary. (4 to 9 inches thick)
A2--9 to 21 inches; brown (7.5YR 4/2) silt loam, dark brown (7.5YR 3/2) moist; moderate very fine and fine granular structure; soft, friable, slightly sticky and plastic; many fine roots; many very fine interstitial pores; noneffervescent; moderately acid (pH 6.0); clear wavy boundary. (5 to 14 inches thick)
Bt1--21 to 29 inches; reddish brown (5YR 4/3) gravelly loam, dark reddish brown (5YR 3/3) moist; weak medium granular and weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and plastic; many coarse roots; many fine interstitial and common fine tubular pores; few faint clay films on faces of peds; noneffervescent; slightly acid (pH 6.2); clear smooth boundary. (8 to 13 inches thick)
Bt2--29 to 41 inches; reddish brown (5YR 4/4) gravelly loam, dark reddish brown (5YR 3/4) moist; weak fine subangular blocky structure; hard, friable, sticky and plastic; many medium and coarse roots; common fine interstitial and tubular pores; few faint clay films on faces of peds and lining pores; noneffervescent; slightly acid (pH 6.2); clear wavy boundary. (9 to 16 inches thick)
2Cr--41 to 61 inches; reddish brown (5YR 5/4) highly weathered basalt and cinders with reddish brown (5YR 4/4) clay loam material coating rock fragments; massive; hard; noneffervescent.
TYPE LOCATION: Apache County, Arizona. Southeast 1/4 of section 1, T. 7 N., R. 25 E.; east of McNary, Arizona.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is not dry in any part for as long as 90 days cumulative per year. Driest during May and June. Typic ustic moisture regime.
Rock fragments: averages less than 35 percent
Depth to weathered bedrock: 40 to more than 60 inches
Mollic epipedon: 16 to 36 inches thick. Organic matter ranges from 1 to 16 percent.
Reaction: Typically slightly acid, but ranges from moderately acid to neutral
Clay content: averages 18 to 35 percent in the control section
A horizon
Hue: 5YR, 7.5YR, 10YR
Value: 3 through 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist
Texture: silt loam, loam
Bt horizon
Hue: 2.5YR, 5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 through 4, dry or moist
Texture: silt loam, loam, clay loam
COMPETING SERIES: These are the Bowbells (ND), Cambern (AZ), Carfall (MT), Center Creek (UT), Chugcreek (WY), Detra (UT), Fiesta (NM), Flaxton (ND), Hereford (AZ), Hesperus (CO), Jaythree (NM), Laceycreek (MT), Ohwiler (CO), Pachel (MT), Schauson (UT), Shermap (CO), Todacheene (NM), Tschicoma (NM) and Weed (CO) series. Bowbells, Carfall, Center Creek, Fiesta, Flaxton, Hereford, Hesperus, Jaythree, Laceycreek, Ohwiler, Pachel, Schauson, Shermap, Todacheene, Tschicoma and Weed soils are very deep. Cambern soils are moderately deep to tuff and ash. Chugcreek soils have a lithic contact of granite at moderate depths. Detra soils have a lithic contact of limestone between 40 and 60 inches deep.
GEOGRAPHIC SETTING: The Gordo soils are on hills and mountains and have slopes of 0 to 50 percent. Elevations are 7,200 to 10,400 feet. The soil formed in basalt, pyroclastic rock including cinders and volcanic ash. Mean annual precipitation is 20 to 30 inches. Mean annual air temperature is about 36 to 45 degrees F. Frost-free period is about 50 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bandera, Brolliar, Sizer, Sponseller and Tatiyee soils. Bandera soils do not have argillic horizons. Brollier and Tatiyee soils are fine textured. Sizer and Sponseller soils have mollic epipedons less than 16 inches thick.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderate permeability.
USE AND VEGETATION: Used for livestock grazing and timber production. Vegetation includes ponderosa pine, fir, spruce and quaking aspen with an understory of Kentucky bluegrass, Arizona fescue and other grasses.
DISTRIBUTION AND EXTENT: Northern Arizona and Colorado. The series is moderately extensive. MLRA is 39.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Apache County, Arizona. Soil survey of Fort Apache Indian Reservation, Arizona; 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 1 to 21 inches (A1, A2, Bt1 horizons)
Argillic horizon - The zone from 21 to 41 inches ( Bt1, Bt2 horizons)
Paralithic contact - The boundary at 41 inches (2Cr horizon)
The nature of the parent materials suggests this soil would be better placed in the Vitrandic Argiustolls subgroup. Laboratory analysis is needed to confirm a classification change.