LOCATION UNAKA TN+NCEstablished Series
TAXONOMIC CLASS: Fine-loamy, isotic, mesic Typic Dystrudepts
TYPICAL PEDON: Unaka loam on a forested east-facing 25 percent slope. (Colors are for moist soil unless otherwise stated.)
A1-- 0 to 3 inches; very dark brown (10YR 2/2) loam; weak medium and fine granular structure; very friable; many fine and medium roots; common fine flakes of mica; 5 percent pebbles; strongly acid; clear smooth boundary. (0 to 9 inches thick)
A2-- 3 to 8 inches; dark brown (10YR 3/3) loam; weak medium granular structure; very friable; many fine and medium roots; common fine flakes of mica; 5 percent pebbles; strongly acid; clear smooth boundary. (0 to 9 inches thick)
Bw1-- 8 to 12 inches; dark yellowish brown (10YR 4/4) loam; weak medium and fine subangular blocky structure; many fine roots; common fine flakes of mica; 5 percent pebbles; strongly acid; clear smooth boundary.
Bw2-- 12 to 24 inches; yellowish brown (10YR 5/4) loam; weak medium subangular blocky structure; friable; common fine roots; common fine flakes of mica; 10 percent pebbles; strongly acid; clear wavy boundary. (Combined thickness of the Bw horizons range from 6 to 18 inches thick.)
Cr-- 24 to 32 inches; granite saprolite that crushes to sandy loam; yellowish brown (10YR 5/4) loam in cracks and seams; strongly acid. (4 to 12 inches thick)
R--32 inches; hard granite bedrock.
TYPE LOCATION: Unicoi County, Tennessee; near top of Divide Mountain at elevation of 4400 feet; 200 yards north of field on abandoned road, 3 miles northeast of benchmark "Sugar"; (Coordinates could not be determined from the description for this revision).
RANGE IN CHARACTERISTICS: Depth to hard granite or gneiss ranges from 20 to 40 inches. Content of rock fragments in the A and B horizons ranges from about 5 to 20 percent and up to as much as 35 percent in the C horizon. Soil reaction is strongly acid or very strongly acid. Flakes of mica range from few to common throughout.
The A horizon has hue of 10YR, value of 2 or 3, and chroma of 2 or 3. Texture of the fine earth is loam, fine sandy loam or sandy clay loam.
The Bw horizon has hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 4 to 6. The fine earth is typically loam, but ranges to clay loam, sandy loam and sandy clay loam in some profiles.
The C horizon (where present) is multicolored saprolite, or has hue of 10YR, value of 5, and chroma of 4 to 6. Texture of the fine earth is sandy loam or loam.
COMPETING SERIES: These include the Brookshire, Jeffrey, and Porters series in the same family, and the Ashe, Burton, and Crossville series in closely related families. Brookshire and Porters soils are deeper than 40 inches to bedrock. Jeffrey soils formed from arkosic sandstone. Ashe soils do not have the dark surface layer. Burton soils have dark surface layers 10 to 20 inches thick and are in a frigid temperature regime. Crossville soils have siliceous mineralogy and are underlain by sandstone.
Note: Competing series have not been updated since most of these will also require reclassification using the 7th Edition of Keys to Soil Taxonomy (1996).
GEOGRAPHIC SETTING: Unaka soils are commonly on high mountains and are underlain by granite and gneiss. Elevations range from 3600 to nearly 5000 feet. They are mainly on east and north aspects. Slopes range from 5 to 80 percent. Mean annual temperature ranges from about 50 to 55 degrees F., and mean annual precipitation is about 46 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Brookshire, Porters and Crossnore (proposed) series and the related Ashe, Burton and Edneytown series. Ashe and Porters soils commonly are at lower elevations and are on south and west aspects. Burton soils commonly are on the domes of high mountains. Brookshire soils are in the coves. Crossnore soils are moderately deep to soft bedrock (Cr). Edneytown soils, which have an argillic horizon, are at lower elevations on less steep slopes.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability. Runoff class is medium on strongly sloping or moderately steep slopes, and high on steeper slopes. Runoff is much lower where forest litter has little or no disturbance.
USE AND VEGETATION: Nearly all areas are in forest consisting chiefly of yellow-poplar, black cherry, oaks, hemlock, buckeye, yellow birch, black birch, beech, and white pine. Cleared areas are used mostly for pasture.
DISTRIBUTION AND EXTENT: The Unaka mountain range in Tennessee and in North Carolina and possibly Virginia. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Lexington, Kentucky
SERIES ESTABLISHED: Unicoi County, Tennessee; 1980.
REMARKS: The 1/97 revision placed Unaka soils in a fine-loamy family. This series was formerly placed in a coarse-loamy family. Laboratory PSA (pipette method) and corresponding field texture estimates (feel method) indicate control section clay contents of generally 12 to 24 percent, with most pedons marginally coarse-loamy. However, chemical lab data indicate that sufficient amorphous, clay-sized materials occur in the particle-size control section to place this soil in a fine-loamy family. Average clay contents are generally less than 25 percent.
This latest revision places Unaka soils in an isotic mineralogy class. Using the 7th Edition of Keys to Soil Taxonomy (1996), Unaka soils would classify as fine-loamy, isotic, mesic Andic Dystrochrepts. However, a proposal has been made to add an acid oxalate-extractable silicon requirement to Andic subgroups, which would exclude Balsam soils, which lack volcanic glass.
Additionally, textures were also modified in the range in characteristics for horizons within the solum.
The 8/2007 revision expanded the slope range for the series from 10 to 60 percent slopes, to 5 to 80 percent slopes
Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon: 0 to 8 inches (A1 and A2 horizons).
Cambic horizon: 12 to 24 inches (Bw horizons).
Lithic contact: hard bedrock at a depth of 32 inches (R).
Isotic mineralogy class - within the PSCS the soil generally has high amorphous materials (high pH-dependent charge) and a high moisture retention (at 1500 kPa) to clay ratio.
Properties that would place the soil in an Andic subgroup--a horizon or horizons with total thickness of 7 inches (18 cm) or more within 30 inches (75 cm) of the mineral soil surface with a fine-earth bulk density of 1.0 g/cm3 or less (at 33 kPa water retention) and ammonium oxalate extractable aluminum plus 1/2 iron percentages totaling more than 1.0.
Revised: 2/94-NTH,DEL; 1/97-DHK, 12/97-DHK, 8/07-HCD