LOCATION COBSTONE TNEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, siliceous, semiactive, thermic Typic Hapludults
TYPICAL PEDON: Cobstone cobbly fine sandy loam on a 2 percent slope in pasture. (Colors are for moist soils)
Ap--0 to 5 inches; dark grayish brown (10YR 4/2) cobbly fine sandy loam; weak medium granular structure; very friable; many fine and common medium roots; many fine tubular pores; 25 percent sandstone cobbles and pebbles 1/8 inch to 5 inches across; strongly acid; clear wavy boundary (3 to 10 inches thick)
BE--5 to 12 inches; strong brown (7.5YR 5/8) very cobbly fine sandy loam; weak medium and fine subangular blocky structure; very friable; common fine and medium roots; many fine and common medium tubular pores; 45 percent sandstone cobbles and pebbles 1/8 inch to 8 inches across; strongly acid; gradual wavy boundary. (7 to 12 inches thick)
Bt1--12 to 28 inches; strong brown (7.5YR 4/6) extremely cobbly sandy clay loam; weak fine subangular blocky structure; very friable; few fine roots; common fine and medium tubular pores; few clay films on faces of peds and some weak bridging of sand grains; 65 percent sandstone cobbles and pebbles 1/8 inch to 12 inches across; strongly acid; gradual wavy boundary.
Bt2--28 to 34 inches; strong brown (7.5YR 5/8) extremely cobbly fine sandy loam; weak fine subangular blocky structure; very friable; common fine and medium tubular pores; few clay films in pores; 75 percent sandstone cobbles and pebbles 1/8 inch to 12 inches across; very strongly acid; gradual wavy boundary. (Thickness of the Bt horizon ranges from 15 to 40 inches)
BC--34 to 63 inches; yellowish brown (10YR 5/8) extremely cobbly sandy loam; weak fine subangular blocky structure; very friable; 80 percent sandstone cobbles, pebbles and stones 1/8 inch to 18 inches across; very strongly acid.
TYPE LOCATION: Bledsoe County, Tennessee; from College Station Mountain Road take Hwy. 28 south 1 mile, site is 350 feet west of road and 150 feet south of Cannon Creek.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 30 to 60 inches or more and depth to bedrock is greater than 60 inches. Reaction is strongly acid or very strongly acid. Rounded cobbles, pebbles and stones range from 25 to 50 percent in the A, E and BE horizons and from 35 to 80 percent in the Bt, BC and C horizons. The rock fragments are mostly sandstone and the dominate size is 3 to 10 inches across but some are as large as 30 inches across. Stones on the surface are more common in wooded areas where they have not been removed.
The A or Ap horizon has hue of 10YR, value of 4 and chroma of 2 to 4. Some pedons have value of 3 in horizons less than 6 inches thick. The fine earth fraction is loam, sandy loam or fine sandy loam. Some pedons have an E horizon with hue of 10YR, value of 5 or 6 and chroma of 2 to 4. The texture is the same as the A horizon.
Many pedons have a transitional horizon between the A or E and the Bt horizon.
The Bt horizon has hue of 10YR or 7.5YR, value of 4 or 5 and chroma of 4 to 8. The fine earth fraction is sandy loam, fine sandy loam, loam, and sandy clay loam.
The BC and C horizons have colors like the Bt horizon. The textures are loam, sandy loam, fine sandy loam or loamy sand.
COMPETING SERIES: These are the Avant, Bigfork, Lillington, Saffell, Steprock, Subligna, and Zafra series in the same family. The Avant and Bigfork soils are underlain by hard chert tilted at 20 to 60 degrees from the horizontal. The Lillington soils formed in gravelly alluvium on high terraces of the Coastal Plain. The Saffell soils formed in loamy and gravelly sediments on Coastal Plains uplands. The Steprock soils formed in residuum and colluvium and are on hillsides and ridges. The Subligna soils have a high content of chert fragments. The Zafra soils are underlain with interbedded sandstone and shale that is tilted 20 to 60 degrees from the horizontal.
GEOGRAPHIC SETTING: Cobstone soils are on alluvial fans and low stream terraces near the base of the Cumberland Plateau escarpment. Slopes range from 0 to 5 percent. These soils formed in loamy local alluvium with a high content of sandstone cobbles and stones. The climate is warm and humid. The mean annual temperature is about 60 degrees F. and the mean annual precipitation is 53 inches near the type location.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Welchland, Sequatchie and Whitwell series. The Sequatchie soils are on adjacent low stream terraces, have less than 35 percent coarse fragments and have a dark surface layer more than 6 inches thick.
The moderately well drained Whitwell soils are on slightly lower lying stream terraces adjoining this soil and have less than 15 percent fragments.
DRAINAGE AND PERMEABILITY: Well drained; Slow runoff; moderately rapid permeability. The soils are not normally flooded, but a few areas are flooded for very brief periods.
USE AND VEGETATION: About fifty percent of the areas of Cobstone soils are cleared and the rest remains in mixed hardwood forest. The cleared land is dominantly pasture or is idle.
DISTRIBUTION AND EXTENT: The areas adjoining the Cumberland Mountains and Cumberland Plateau regions of Tennessee. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Bledsoe County, Tennessee - 1987
REMARKS: Cobstone soils were formerly included in the Welchland series. Laboratory data for the typical pedon was obtained from the National Soil Survey Laboratory: S84TN-007-003. Data is also available for the control section for two additional pedons: S84TN-007-001 and S84TN-007-002.
Diagnostic horizons recognized in this pedon are:
Ochric epipedon - 0 to 5 inches (Ap horizon)
Argillic horizon - 12 to 34 inches (Bt horizon.)