LOCATION THEECAN AZEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Paleustalfs
TYPICAL PEDON: Theecan very cobbly sandy loam - woodland. (Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; brown (10YR 5/3) very cobbly sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium thick platy parting to moderate fine granular structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and few fine roots; common very fine irregular pores; noneffervescent; 20 percent cobble and 25 percent gravel as surface lag; neutral (pH 6.6); abrupt smooth boundary. (2 to 4 inches thick)
BA--2 to 5 inches; brown (7.5YR 4/2) sandy clay loam, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine irregular and tubular pores; noneffervescent; neutral (pH 6.6); abrupt smooth boundary. (0 to 4 inches thick)
Bt1--5 to 9 inches; mixed brown (7.5YR 4/2) and yellowish red (5YR 4/6) sandy clay, dark brown (7.5YR 3/2) and yellowish red (5YR 4/6) moist; weak coarse prismatic structure; hard, firm, sticky and very plastic; few very fine and medium and common fine roots; common very fine irregular pores; common faint clay films on ped faces and in pores; common pressure faces; noneffervescent; neutral (pH 6.6); clear smooth boundary. (3 to 6 inches thick)
Bt2--9 to 23 inches; yellowish red (5YR 4/6) clay, yellowish red (5YR 4/6) moist; moderate coarse prismatic structure; very hard, very firm, very sticky and very plastic; few very fine and fine, common medium roots; common very fine irregular and few very fine tubular pores; common faint clay films on ped faces and in pores; many pressure faces and few slickensides; noneffervescent; neutral (pH 6.8); gradual smooth boundary. (12 to 15 inches thick)
Bt3--23 to 33 inches; yellowish red (5YR 4/6) sandy clay, yellowish red (5YR 4/6) moist; weak coarse prismatic structure; very hard, firm, very sticky and very plastic; few fine to medium roots; common fine irregular and few fine tubular pores; common faint clay films on ped faces and in pores; common pressure faces and few slickensides; common faint coatings of sand grains on ped faces; noneffervescent; neutral (pH 7.0); gradual smooth boundary. (8 to 12 inches thick)
Bt4--33 to 40 inches; mixed yellowish red (5YR 5/6) and strong brown (7.5YR 5/6) sandy clay, yellowish red (5YR 4/6) and strong brown (7.5YR 4/6) moist; moderate medium prismatic structure; hard, firm, sticky and very plastic; few very fine and fine roots; common very fine irregular and few very fine tubular pores; common faint clay films on ped faces and in pores; noneffervescent to slightly effervescent; neutral (pH 7.2); abrupt smooth boundary. (5 to 10 inches thick)
2C--40 to 58 inches; mixed yellowish red (5YR 5/6) and strong brown (7.5YR 5/6) extremely gravelly loamy coarse sand, yellowish red (5YR 4/6) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine to medium roots; common very fine and fine irregular pores; noneffervescent to slightly effervescent; 65 percent gravel and 10 percent cobble; neutral (pH 7.2); abrupt smooth boundary. (0 to 18 inches thick)
3C--58 to 65 inches; mixed yellowish red (5YR 5/6) and yellowish red (5YR 4/6), and strong brown 7.5YR 5/6) sandy clay loam, yellowish red (5YR 5/6) and yellowish red (5YR 4/6) moist; massive; slightly hard, friable, slightly sticky and nonplastic; few very fine and fine roots; common very fine irregular pores; noneffervescent to slightly effervescent; neutral (pH 7.2).
TYPE LOCATION: Coconino County, Arizona; on the Hualapai Indian Reservation; 1400 feet west and 850 feet south of the northeast corner of section 17, T. 28 N., R. 7 W.
RANGE IN CHARACTERISTICS:
Soil Moisture: Moist in some part of the soil moisture control section during December - March and intermittently moist during July - September. Driest during May and June. Typic ustic soil moisture regime.
Soil Temperature: 52 to 56 degrees F.
Rock fragments: Less than 15 percent gravel in the control section
Clay content: Averages 35 to 50 percent in the control section
Linear extensibility: 6.0 cm or more from the surface horizon to 40 inches
A horizon
Hue: 10YR, 7.5YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 or 3, dry or moist
Bt horizons
Hue: 5YR, 7.5YR
Value: 4 through 6, dry or moist
Chroma: 2 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: Less than 5 percent
C horizons
Hue: 5YR, 7.5YR
Value: 4 or 5, dry or moist
Chroma: 5 or 6, dry or moist
Texture: Stratified sandy clay loam and loamy coarse sand
Calcium carbonate equivalent: 0 to 10 percent
Some pedons may have a few soft masses of calcium carbonate and others may have strata high in gravel content.
COMPETING SERIES: These are the Pinntank (AZ) and Tovar (AZ) series. Pinntank and Tovar soils are moderately deep to bedrock.
GEOGRAPHIC SETTING: Theecan soils are on fan terraces at elevations of 6200 to 6800 feet. These soils formed in dissected tertiary alluvium from mixed rock sources. Slopes range from 2 to 35 percent. The mean annual air temperature is 50 to 54 degrees F. The mean annual precipitation is 18 to 20 inches. Frost-free period is 120 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Pinespring, Jacques, Frazwell, Pocomate, and Deama soils. Pinespring and Jacques soils have a mollic epipedon. Frazwell soils are fine-loamy. Pocomate and Deama soils are shallow to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.
USE AND VEGETATION: Theecan soils are used for timber harvesting, firewood gathering, and grazeable woodland. The present vegetation is ponderosa pine, bottlebrush squirreltail, blue grama, Gambel oak, turbinella oak, and desert ceanothus.
DISTRIBUTION AND EXTENT: Northern Arizona. This series is not extensive. MLRA 35.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Coconino County, Arizona; Soil survey of the Hualapai-Havasupai Area, AZ, Parts of Coconino, Mohave, and Yavapai Counties; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 5 inches (A, BA horizons)
Argillic horizon - The zone from 5 to 40 inches (Bt1, Bt2, Bt3, Bt4 horizons)
Vertic subgroup - Linear extensibility of 6.0 cm or more to 40 inches
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy Tenth Edition, 2006.