LOCATION STEPROCK AREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, siliceous, subactive, thermic Typic Hapludults
TYPICAL PEDON: Steprock very flaggy loam, 16 percent slopes in woodland.
(Colors are for moist soil unless otherwise stated.)
Oi--1 to 0 inches; partly decomposed organic matter.
A--0 to 1 inch; dark grayish brown (10YR 4/2) very flaggy loam; weak fine granular structure; very friable; few fine roots; about 20 percent by volume gravel 1/4 to 3 inches in diameter and 20 percent by volume flat fragments of sandstone 3 to 10 inches in diameter; strongly acid; abrupt smooth boundary. (0 to 3 inches thick)
E--1 to 3 inches; brown (10YR 5/3) very flaggy loam; weak fine subangular blocky structure; friable; few fine roots; few fine pores; about 20 percent by volume flat fragments of sandstone 3 to 10 inches in diameter; strongly acid; clear smooth boundary. (2 to 6 inches thick)
BE--3 to 9 inches; yellowish brown (10YR 5/8) very flaggy fine sandy loam; weak medium subangular blocky structure; friable; many fine and medium roots; common fine pores; about 20 percent by volume gravel 1/4 to 3 inches in diameter and 20 percent by volume flat fragments of sandstone 3 to 10 inches in diameter; very strongly acid; clear smooth boundary. (0 to 8 inches thick)
Bt1--9 to 16 inches; strong brown (7.5YR 5/8) very gravelly loam; weak fine and medium subangular blocky structure; friable; many fine and medium roots; common medium pores; few thin patchy clay films; about 20 percent by volume gravel 1/4 to 3 inches in diameter and about 15 percent by volume flat fragments of sandstone 3 to 10 inches in diameter; very strongly acid; clear wavy boundary. (4 to 9 inches thick)
Bt2--16 to 24 inches; yellowish red (5YR 5/8) very gravelly loam; moderate fine and medium subangular blocky structure; friable; common fine and medium roots; few medium pores; many thin patchy clay films on faces of peds and in pores; about 35 percent by volume gravel 1/4 to 3 inches in diameter and about 20 percent by volume flat fragments of sandstone 3 to 15 inches in diameter; few medium distinct strong brown (7.5YR 5/6) iron depletions in matrix; very strongly acid; gradual wavy boundary. (6 to 10 inches thick)
Bt3--24 to 28 inches; yellowish red (5YR 5/8) very gravelly loam; weak fine subangular blocky structure; very friable; few fine roots; about 75 percent by volume weathered fragments of sandstone 1/4 to 10 inches in diameter; few thin vertical streaks of loamy sand coated with thin clay films; very strongly acid; clear irregular boundary. (3 to 6 inches thick)
Cr--28 to 48 inches; yellowish red (5YR 5/8) weathered sandstone bedrock with thin vertical interstices filled with sand.
TYPE LOCATION: White County Arkansas; 1.9 miles west on county road from Ark. Hwy., 31 at Floyd in NE1/4SE1/4SW1/4 sec. 29, T. 7 N., R 9 W.
RANGE IN CHARACTERISTICS: Solum thickness and depth to Cr horizons range from 20 to 40 inches. Depth of unweathered hard bedrock is 60 inches or more. Reaction is strongly acid or very strongly acid except where surface layers are limed.
The A horizon has hue of 10YR, value of 3, 4, or 5, and chroma of 2 or 3. Ap horizons have hue of 10YR, value of 4 or 5 and chroma of 3 or 4. The fine earth fraction is sandy loam, loam, silt loam, or fine sandy loam. Gravelly, very gravelly, very flaggy, stony, and very stony phases are recognized. Sandstone, siltstone, or shale fragments less than 3 inches in diameter range from 15 to 45 percent and larger fragments range from 5 to 30 percent by volume.
The E horizon has hue of 10YR, value of 5 or 6 and chroma of 3 or 4. The fine earth fraction is sandy loam, loam, silt loam, or fine sandy loam. Gravelly, very gravelly, flaggy or very flaggy phases are recognized. Sandstone, siltstone, or shale fragments less than 3 inches in diameter range from 15 to 45 percent and larger fragments range from 5 to 30 percent by volume.
The BE horizon has hue of 10YR, 7.5YR or 5YR, value of 5 and chroma of 6 or 8. The fine earth fraction is sandy loam, fine sandy loam, or loam. Gravelly, very gravelly, flaggy or very flaggy phases are recognized. Sandstone, siltstone, or shale fragments less than 3 inches in diameter range from 15 to 45 percent and larger fragments range from 5 to 30 percent by volume.
The Bt horizon has hue of 5YR or 2.5YR, value of 4 or 5, and chroma of 6 or 8. In some pedons the lower part of the Bt horizon has hue of 7.5YR, value of 5 and chroma of 6 or 8. Iron accumulations and depletions are in shades of red or brown. Texture is sandy clay loam, clay loam, silt loam, or loam with textural modifier of very gravelly or very flaggy. Sandstone, siltstone, or shale fragments less than 3 inches in diameter range from 30 to 50 percent and larger fragments range from 5 to 20 percent by volume.
The BC horizon, if present, has colors similar to that of the Bt horizon. Textures of the fine earth fractions are sandy loam, fine sandy loam, loamy fine sand, loamy sand, and silt loam. The percent of coarse fragments is similar to the Bt horizon.
Some pedons have C horizons about 1 to 6 inches thick. Textures of the fine earth fractions are sandy loam, fine sandy loam, loamy fine sand, loamy sand, sand, or silt loam. Sandstone, siltstone, or shale fragments less than 3 inches in diameter range from 30 to 50 percent and larger fragments range from 5 to 20 percent by volume.
The Cr horizon is partly weathered sandstone, or siltstone, shale, or interbedded layers of these materials. Hardness of the material on Moh's scale range from 1.5 to 3.
COMPETING SERIES: These are the Bigfork, Lillington, Saffell, Subligna, and Zafra series. Bigfork soils are underlain by hard chert and tilted 20 degrees to 60 degrees from the horizontal. Lillington soils have sola more than 60 inches thick. Saffell and Subligna soils lack bedrock within 60 inches. Zafra soils are underlain with interbedded sandstone and lenses of shale tilted at 20 degrees to 60 degrees from the horizontal
GEOGRAPHIC SETTING: Steprock soils are on sideslopes of ridges and hills at intermediate elevations of the uplands in MLRAs 117 and 118. These soils dominantly have slopes between 8 and 20 percent but range from 3 to 60 percent. The soil formed in loamy residuum or residuum and colluvium weathered from sandstone, siltstone, and shale of the Atoka formation or similar acid low base bedrock. Near the type location, average annual temperature ranges from 60 degrees to 63 degrees F., and average annual precipitation ranges from 45 to 50 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Enders, Leadvale, Leesburg, Linker, Mountainburg, and Nella series. Enders soils have more than 35 percent clay and less than 35 percent coarse fragments in the upper 20 inches of the argillic horizon and are at lower elevations. Leesburg and Nella soils have less than 35 percent coarse fragments in the upper 20 inches of the argillic horizon and are on slightly lower sideslopes. Leadvale soils have a fragipan and are on lower lying sideslopes, valley fill and terraces. Linker soils are underlain by hard sandstone and are on nearby plateaus and benches. Mountainburg soils are shallow to hard sandstone and are on higher ridgetops or adjacent benches.
DRAINAGE AND PERMEABILITY: Steprock soils are well drained. Runoff is medium or rapid and permeability is moderate.
USE AND VEGETATION: Most of these soils are used for pasture. Forests are blackjack, post, red and white oaks, blackgum, hickory, and shortleaf pine. A small amount is used for cultivatd row crops.
DISTRIBUTION AND EXTENT: Boston Mountains, Arkansas Valley and Ridges of Arkansas and Oklahoma. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Little Rock, Arkansas
SERIES ESTABLISHED: White County, Arkansas; 1980.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon--surface to a depth of 9 inches.
Argillic horizon--depth between 9 and 28 inches.
Paralithic contact--28 to 48 inches
These soils were formerly included with the Linker series.