LOCATION VIEWPOINT NM+AZEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, frigid Lithic Argiustolls
TYPICAL PEDON: Viewpoint gravelly loam, very stony -- on a convex knoll sloping 8 percent to the southwest at 8,890 feet elevation -- forest. The surface has a discontinuous cover of needles, twigs and cones. (Colors are for dry soil unless otherwise noted. When described, the soil was moist from 0 to 8 inches, and dry below to the bedrock contact.)
A-- 0 to 3 inches; brown (7.5YR 4/2) gravelly loam, very dark brown (7.5YR 2/2) moist; weak thick platy structure parting to moderate medium granular; soft, very friable, slightly sticky and nonplastic; few fine and common very fine roots; common very fine irregularly shaped pores; 15 percent gravel and 2 percent stones; slightly acid (pH 6.4); clear smooth boundary. (2 to 4 inches thick)
Bt1-- 3 to 7 inches; brown (7.5YR 4/3) gravelly sandy clay loam, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few coarse, few medium, few fine, and common very fine roots; few very fine tubular pores; few faint clay films on faces of peds; 25 percent gravel and 5 percent cobbles; neutral (pH 6.6); clear wavy boundary.
Bt2-- 7 to 17 inches; brown (7.5YR 4/3) cobbly sandy clay loam, dark brown (7.5YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few coarse, few medium, few fine, and few very fine roots; few very fine tubular pores; common faint clay films on faces of peds and on rock fragments; 15 percent cobbles, 15 percent gravel, and 5 percent stones; neutral (pH 6.6); clear wavy boundary. (Combined thickness of the Bt horizons is 8 to 18 inches)
2R-- 17 inches; basalt bedrock.
TYPE LOCATION: San Juan County, New Mexico; on the Navajo Indian Reservation about 9.5 miles west-southwest of Sheep Springs; 750 feet north and 2,000 feet west of the southeast corner of sec.28, T.22N., R.19W.; Latitude 36 degrees 6 minutes 23 seconds N and Longitude 108 degrees 52 minutes 10 seconds W.
RANGE IN CHARACTERISTICS:
Soil moisture - Typically, the soil moisture control section is moist in all parts from January to May and intermittently moist in some part from June to December. The soil is driest during July and August. Typic ustic soil moisture regime.
Soil temperature: 41 to 44 degrees F.
Mean summer soil temperature: 59 to 63 degrees F.
Soil depth: 10 to 20 inches to hard bedrock
Reaction: slightly acid or neutral
Silicate clay content, control section weighted average: 20 to 35 percent
Sand content: fine sand and coarser is 35 to 65 percent
Rock fragment content, control section weighted average: 15 to 35 percent
Depth to base of argillic horizon: 10 to 20 inches
Organic carbon content: 0.6 to 3.4 percent
A horizon
Hue: 5YR, 7.5YR.
Value: 3 or 4 dry, 2 or 3 moist
Chroma: 1 or 2, dry or moist
Texture: gravelly loam or very gravelly loam
Rock fragments: 15 to 60 percent; 15 to 35 percent gravel, 0 to 15 percent cobbles, 0.5 to 10 percent stones and boulders
Bt1 horizon
Hue: 5YR, 7.5YR.
Value: 3 through 5 dry, 2 through 4 moist
Chroma: 2 or 3, dry or moist
Texture: loam, sandy clay loam, clay loam with appropriate modifiers
Clay content: 18 to 35 percent
Rock fragments: 15 to 35 percent; 15 to 30 percent gravel, 0 to 15 percent cobbles, 0 to 5 percent stones
COMPETING SERIES: These are the Beje (UT), Berland (NM), Bonjea (WY), Cedric (MT), Coni (CO), Connieo (MT), Kiln (NM) and Skyute (CO) series. Beje soils are drier in the spring and typically are more alkaline and have hue yellower than 7.5YR. Berland soils are very shallow and have less than 15 percent rock fragments. Bonjea soils are drier and have mean summer soil temperatures of 60 to 68 degrees F. Cedric soils have granite rock fragments dominantly 2 to 10 mm in diameter and have accumulations of secondary calcium carbonate. Coni soils are more moist in the late spring and early summer and typically have hue yellower than 7.5YR. Connieo soils have granitic rock fragments dominantly 2 to 7 mm in diameter. Kiln soils are drier, have less than 35 percent medium and coarser sand in the argillic horizon, and are typically more alkaline. Skyute soils have less than 15 percent rock fragments.
GEOGRAPHIC SETTING: Viewpoint soils are on shoulders and knolls of mesas and calderas, and shoulders of hills, buttes, and escarpments. They formed in alluvium, colluvium, and residuum derived from Tertiary basalt and tuff-breccia. Slopes are 2 to 35 percent. Elevation ranges from 8,200 to 9,800 feet. The mean annual precipitation is 20 to 24 inches with more than 50 percent falling as snow from winter storms. The mean annual temperature is 39 to 42 degrees F. The average frost-free period is 60 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Owlspring, Sonsela, Todacheene, and Washpass soils. Owlspring soils are fine-silty, very deep, and occur on adjacent toeslopes. Sonsela soils are loamy-skeletal, very deep, and occur on backslopes. Todacheene soils are very deep, non-wooded, and occur on adjacent footslopes and fan terraces. Washpass soils are very deep, have a cryic temperature regime, and are on north-facing slopes.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability
USE AND VEGETATION: Viewpoint soils are used for timber production and livestock grazing. Present vegetation is ponderosa pine and Douglas fir with an understory of Kentucky bluegrass, muttongrass, earth sedge, bottlebrush squirreltail, prairie junegrass, Arizona fescue, Oregongrape, Gambel oak, and mountain snowberry.
DISTRIBUTION AND EXTENT: Viewpoint soils are of small extent on the Defiance Uplift-Chuska Mountains portion of the Colorado Plateau province in northwest New Mexico and northeast Arizona. MLRA 35, LRR-D.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: San Juan County, New Mexico, Shiprock Area Soil Survey, 1993. Viewpoint is a local place name for a mesa in the survey area.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 17 inches (A, Bt1, and 2Bt2 horizons)
Argillic horizon - The zone from 3 to 17 inches (Bt1 and 2Bt2 horizons)
Lithic contact - The boundary with hard bedrock at 17 inches (2R layer)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.
ADDITIONAL DATA: Organic carbon values determined for one pedon by Inter-Mountain Laboratories, Inc.
Updated and revised for the correlation of Ft. Defiance Area AZ715 2/08 DWD