LOCATION PINNTANK AZEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Paleustalfs
TYPICAL PEDON: Pinntank loam - woodland. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inches; recent and slightly decomposed pine litter.
A--1 to 3 inches; brown (7.5YR 4/3) loam, dark brown (7.5YR 3/3) moist; weak fine granular structure; soft, very friable, sticky and plastic; many very fine roots; many very fine irregular pores; 10 percent gravel; noneffervescent; neutral (pH 6.8); abrupt smooth boundary. (2 to 5 inches thick)
Bw--3 to 8 inches; brown (7.5YR 4/2) clay loam, very dark brown (7.5YR 2/2) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky and plastic; many very fine, few fine and medium roots; common very fine irregular and tubular pores; 5 percent gravel; noneffervescent; neutral (pH 6.6); abrupt wavy boundary. (0 to 7 inches thick)
Bt1--8 to 14 inches; reddish brown (5YR 5/4) clay, reddish brown (5YR 4/4) moist; strong coarse subangular blocky structure; hard, firm, very sticky and very plastic; common very fine, fine and medium, and few coarse roots; common very fine tubular pores; 10 percent gravel; common faint clay films in pores and on ped faces; noneffervescent; neutral (pH 6.8); clear wavy boundary. (4 to 9 inches thick)
Bt2--14 to 25 inches; reddish brown (5YR 4/4) and yellowish red (5YR 4/6) clay, reddish brown (5YR 4/4) and yellowish red (5YR 4/6) moist; strong coarse prismatic structure; very hard, very firm, very sticky and very plastic; few very fine and fine roots; few very fine tubular pores; 5 percent gravel; common faint clay films in pores and on ped faces, many pressure faces; noneffervescent; neutral (pH 6.8); abrupt wavy boundary. (9 to 16 inches thick)
R--25 inches; cherty limestone.
TYPE LOCATION: Coconino County, Arizona; on the Hualapai Indian Reservation; 1600 feet west and 1400 feet north of the southeast corner of Section 27, T.29N., R.8W.
RANGE IN CHARACTERISTICS:
Soil Moisture: Moist in some part of the soil moisture control section during January - March and intermittently moist during July - September. Driest during May and June. Approximately 60 percent of the precipitation occurs during the winter months. Typic ustic soil moisture regime.
Depth to bedrock: 20 to 40 inches
Soil Temperature: 47 to 51 degrees F.
Rock fragments: averages less than 25 percent gravel throughout
Clay content: 40 to 60 percent in the particle size control section, but ranges from 35 to 65 percent in any individual horizon
Linear extensibility: 6.0 cm or more from the surface horizon to bedrock
A horizon
Hue: 7.5YR, 10YR
Value: 3 through 5 dry, 2 through 4 moist
Chroma: 2 through 4, dry or moist
Bw horizon
Hue: 7.5YR, 10YR
Value: 4 through 6 dry, 2 through 5 moist
Chroma: 2 through 5, dry or moist
Texture: fine sandy loam, loam, sandy clay loam, clay loam
Bt horizon
Hue: 5YR, 2.5YR
Value: 4 through 6 dry, 3 through 5 moist
Chroma: 4 through 6, dry or moist
Texture: sandy clay, clay (15 percent or more (absolute) clay increase at the upper boundary within a vertical distance of 1 inch)
Calcium carbonate equivalent: Typically noneffervescent, but ranges to 5 percent calcium carbonate equivalent in some pedons immediately above the lithic contact
The Oi and/or the Bw horizons are absent in some pedons. Some pedons contain Cr horizons of weathered sandstone above unweathered bedrock.
COMPETING SERIES: These are the Theecan (AZ) and Tovar (AZ) series. Theecan soils are very deep and Tovar soils have an aridic ustic soil moisture regime.
GEOGRAPHIC SETTING: Pinntank soils are on plateaus and mesas at elevations of 6600 to 7400 feet. These soils formed in residuum derived from interbedded limestone and sandstone bedrock of the Kaibab Formation. Slopes range from 1 to 15 percent. The mean annual air temperature is 45 to 49 degrees F. The mean annual precipitation is 18 to 20 inches. The frost-free period is 120 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Pocomate and Retsover series. Pocomate soils are shallow to bedrock. Retsover soils are deep to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; slow permeability.
USE AND VEGETATION: Pinntank soils are used for timber production, firewood gathering, grazeable woodland, and wildlife habitat. The present vegetation is ponderosa pine, bottlebrush squirreltail, Ross sedge, blue grama, Gambel oak, and hairy goldaster.
DISTRIBUTION AND EXTENT: Northwestern Arizona. This series is not extensive. MLRA 39.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Coconino County, Arizona; Soil survey of Hualapai-Havasupai Area, Parts of Coconino, Mohave and Yavapai Counties; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 1 to 3 inches (A horizon)
Argillic horizon - The zone from 8 to 25 inches (Bt1, Bt2 horizons)
Lithic contact - The boundary at 25 inches (R horizon)
Vertic subgroup - Linear extensibility of 6.0 cm or more to bedrock
Pale feature - Clay increase of 15 percent or more within 1 inch at upper boundary of Bt