Established Series
Rev. WDC


The Elioak series consists of very deep, well drained, moderately permeable soils on uplands. They formed in materials weathered from micaceous crystalline rocks. Slopes range from 0 to 30 percent. Mean annual temperature is 50 degrees F., and mean annual precipitation is 40 inches.

TAXONOMIC CLASS: Fine, kaolinitic, mesic Typic Hapludults

TYPICAL PEDON: Elioak silt loam - in a cultivated field (colors are for moist soil unless otherwise stated)

Ap-- 0 to 6 inches; dark yellowish brown (10YR 4/4) silt loam; weak fine granular structure; slightly hard, very friable; many fine roots; moderately acid; abrupt smooth boundary. (4 to 10 inches thick)

E-- 6 to 10 inches; yellowish brown (10YR 5/4) silt loam; weak fine and medium granular structure; slightly hard, very friable; common fine roots; strongly acid; gradual smooth boundary. (2 to 6 inches thick)

BE-- 10 to 15 inches; yellowish red (5YR 5/6) silt loam; weak fine subangular structure; hard, friable, slightly sticky, slightly plastic; few fine roots; strongly acid; gradual smooth boundary. (3 to 7 inches thick)

Bt1-- 15 to 33 inches; red (2.5YR 4/6) silty clay loam; moderate fine subangular structure; hard, friable, sticky and slightly plastic; few fine roots; thick continuous clay films; common fine mica flakes; strongly acid; gradual wavy boundary.

Bt2-- 33 to 42 inches; variegated red (2.5YR 5/6), yellowish red (5YR 5/6), and strong brown (7.5YR 5/6) silty clay loam; weak medium structure; slightly hard, friable, slightly sticky and slightly plastic; very few fine roots; many thick continuous clay films; common fine mica flakes; strongly acid; gradual wavy boundary. (Combined thickness of the Bt is 16 to 32 inches thick)

C-- 42 to 65 inches; variegated yellowish red (5YR 4/6), red (10R 5/8), light red (10R 6/8), and reddish yellow (7.5YR 6/8) silt loam; variegations are fine and distinct with cut faces having a brindled appearance; saprolite with laminar structure; soft, very friable; highly micaceous; strongly acid.

TYPE LOCATION: Montgomery County, Maryland; about two miles north of Rockville, 50 feet east of the intersection of Chieftain Avenue and Derwood Road.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 30 to 50 inches. Depth to bedrock ranges from 5 to 10 feet. Angular rock fragments of white quartzite, from gravel to stone size, range from 0 to 20 percent by volume throughout and are commonly most abundant on or near the surface. Mineralogy is dominated by kaolinite. Unlimed reaction ranges from medium acid to very strongly acid.

The A and E horizons have hue of 5YR to 10YR, value of 3 to 5, and chroma of 2 to 4. Value of 3 is confined to the A horizon, which is less than 4 inches thick. The A horizon is silt loam, loam, clay loam, fine sandy loam high in silt, or their gravelly analogues.

The B horizons have hue of 10R to 5YR, value of 3 to 5, and chroma of 4 to 8 except in subhorizons that are variegated, which may have hue that is less red. The Bt horizons range from silty clay loam or clay loam to silty clay with the average clay content of the particle size control section between 35 and 45 percent. Clay films are of the same color as the matrix or are one unit lower in value, chroma, or both.

The BC horizon (where present) has hue of 10R to 7.5YR, value of 3 through 6, and chroma of 4 through 8. The BC horizon is loam, silt loam or fine sandy loam, but includes textures of the Bt horizons. The tendency toward platiness in the lower Bt and BC horizons are inherent from rock structure.

The C horizon is commonly variegated in shades of red and yellow, but in some pedons the color is uniform in hue of 10R to 7.5YR with value of 4 through 7 and chroma of 3 through 8. The C horizon is loam, silt loam or fine sandy loam, or less commonly silty clay loam. The C horizon has a higher mica content than the solum. It is 15 inches to several feet in thickness.

COMPETING SERIES: The Culpeper and Minnieville series are in the same family. Culpeper soils have rock fragments of sandstone, chert, or other mixtures of sedimentary rocks. Minnieville soils have developed over hornblende gneiss and hornblende schist and do not have fragments of quartz muscovite schist.

The Agnos, Appling, Braddock, Cecil, Christiana, Dunmore, Frederick, Georgeville, Groseclose, Hayesville, Herndon, Howell, Hulett, Madison, Mayodan, Muse, Norton, Pacolet, Sequoia, Trappist, Turbeville, Unison, and Wedowee series are similar soils in related families. Agnos, Braddock, Groseclose, Howell, Muse, Norton, Sequoia, Trappist, and Unison soils have mixed mineralogy. The Appling, Cecil, Georgeville, Herndon, Hulett, Madison, Mayodan, Pacolet, and Wedowee soils have a thermic temperature regime. The Christiana, Dunmore, Frederick, and Turbeville soils have sola thicker than 60 inches; in addition, the Turbeville soils have a thermic temperature regime. Hayesville soils have oxidic mineralogy.

GEOGRAPHIC SETTING: Elioak soils occupy summits and upper slopes in northern portions of the Piedmont Plateau. Most slopes are less than 15 percent but range from 0 to 30 percent. The soils formed in residuum weathered from mica schists and phyllites, and to a minor extent from granitized schist and micaceous gneiss. The climate is temperate and humid with a mean annual temperature of 45 to 55 degrees F. and mean annual precipitation of 40 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brandywine, Chester, Codorus, Comus, Glenelg, Glenville, Hatboro, Legore, Linganore, Manor, Montalto, Mt. Airy, and Neshaminy. Brandywine, Codorus, Comus, Hatboro, and Neshaminy soils do not have an argillic horizon. Linganore and Mt. Airy soils are in a loamy-skeletal particle-size family. Chester, Glenelg, Glenville, Legore, and Neshaminy soils have less than 35 percent clay in the particle-size control section. Legore, Linganore, Montalto, and Neshaminy soils have base saturation of greater than 35 percent in the C horizon. Codorus, Comus, and Hatboro soils are on floodplains. Glenville soils are on footslopes or near the heads of drainageways. Brandywine, Chester, Glenelg, Legore, Linganore, Manor, Montalto, Mt. Airy, and Neshaminy soils are in topographic positions similar to those of the Elioak soils.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to rapid. Permeability is moderate.

USE AND VEGETATION: Elioak soils are in pastures, orchards, general local crops, and nonagricultural uses. Native vegetation consists of black oak, yellow poplar, black walnut and Virginia pine.

DISTRIBUTION AND EXTENT: Pennsylvania, Delaware, Maryland, and Virginia. The series is of moderate extent.


SERIES ESTABLISHED: York County, Pennsylvania, 1939.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

a. Argillic horizon - the zone from approximately 15 to 42 inches

b. Typic Udults feature - have a udic moisture regime and base saturation by sum of cations of less than 35 percent 1.25m below the upper boundary of the argillic horizon, or 1.8m below the surface of the soil, or immediately above a lithic or paralithic contact, whichever is shallowest.

Additional Data: Lab data from Elioak pedon No. S57MD 13-2 published in Soil Characterization Studies in Maryland; Summary of Data 1950-1966. Soil Survey Series No. 1. March, 1969.

National Cooperative Soil Survey