LOCATION EL DARA            IL
Established Series
Rev. LJB-JWS, RC-RT
5/98

EL DARA SERIES


The El Dara series consists of very deep, moderately well drained, moderately permeable soils formed in stratified loamy and sandy Cretaceous age materials on uplands. Slope gradients range from 5 to 60 percent. Mean annual precipitation is about 34 inches, and mean annual temperature is about 52 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Oxyaquic Hapludalfs

TYPICAL PEDON: El Dara silt loam on a northwest facing convex slope of 7 percent in a pasture that has been cultivated at an elevation of about 780 feet. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 6 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) and light yellowish brown (10YR 6/4) dry; weak thin platy structure parting to moderate fine subangular blocky; friable; many very fine roots throughout and few fine roots between peds; moderately acid; clear smooth boundary. (6 to 9 inches thick)

Bt1--6 to 9 inches; brown (10YR 5/3) loam; moderate medium subangular blocky structure; friable; common fine roots throughout and many very fine roots between peds; few distinct brown (10YR 4/3) clay films on faces of peds; moderately acid; clear smooth boundary.

Bt2--9 to 17 inches; yellowish brown (10YR 5/4) loam; weak coarse prismatic structure parting to moderate medium subangular blocky; friable; common fine roots throughout and many very fine roots between peds; common distinct light gray (10YR 7/1) silt coats on faces of peds and common faint dark yellowish brown (10YR 4/4) clay films on faces of peds and in pores; few fine distinct black (2.5Y 2/1) masses of iron and manganese accumulation throughout; very strongly acid; clear wavy boundary.

Bt3--17 to 27 inches; light yellowish brown (10YR 6/4) clay loam; weak medium prismatic structure parting to moderate medium subangular blocky; friable; many very fine roots between peds; few prominent light gray (10YR 7/2) silt coats on faces of peds and common distinct dark yellowish brown (10YR 4/4) clay films on faces of peds and in pores; few fine distinct yellowish brown (10YR 5/6) masses of iron and manganese accumulation between peds; very strongly acid; clear smooth boundary.

Bt4--27 to 31 inches; light yellowish brown (10YR 6/4) loam; weak medium subangular blocky structure; friable; few very fine roots between peds; very few prominent light gray (10YR 7/2) silt coats on faces of peds and few prominent dark yellowish brown (10YR 4/4) clay films on faces of peds; common fine distinct yellowish brown (10YR 5/6) masses of iron accumulation throughout; very strongly acid; gradual wavy boundary.

Bt5--31 to 39 inches; brownish yellow (10YR 6/6) sandy loam; weak medium subangular blocky structure; friable; few very fine roots between peds; few prominent dark yellowish brown (10YR 4/4) clay films on faces of peds; common fine faint yellowish brown (10YR 5/6) masses of iron accumulation throughout; very strongly acid; gradual wavy boundary.

Bt6--39 to 53 inches; light yellowish brown (10YR 6/4) sandy loam; weak coarse prismatic structure parting to weak coarse subangular blocky; friable; few very fine roots between peds; few prominent dark yellowish brown (10YR 4/4) clay films on faces of peds and in pores; common fine distinct yellowish brown (10YR 5/8) masses of iron accumulation throughout and common medium distinct light brownish gray (10YR 6/2) iron depletions throughout; very strongly acid; clear wavy boundary.

Bt7--53 to 61 inches; light yellowish brown (10YR 6/4) loam; weak coarse prismatic structure; friable; very few prominent dark yellowish brown (10YR 4/4) clay films on faces of peds and very few prominent light gray (10YR 7/1) silt coats on faces of peds; few fine distinct strong brown (7.5YR 5/8) masses of iron accumulation throughout, common medium distinct reddish yellow (7.5YR 6/8) masses of iron accumulation throughout and common medium distinct light brownish gray (10YR 6/2) iron depletions throughout; very strongly acid; clear wavy boundary. (Combined thickness of the Bt horizon is 32 to 55 inches)

BC--61 to 66 inches; light yellowish brown (10YR 6/4) sandy clay loam; moderate coarse prismatic structure; friable; very few distinct yellowish brown (10YR 5/4) clay films on faces of peds and in pores and common prominent light gray (10YR 7/1) silt coats on faces of peds and in pores; common fine distinct strong brown (7.5YR 5/8) masses of iron accumulation throughout, common medium distinct reddish yellow (7.5YR 6/8) masses of iron accumulation throughout, common coarse distinct yellowish brown (10YR 5/6) masses of iron accumulation throughout, and common fine distinct light brownish gray (10YR 6/2) iron depletions throughout; 1 percent rounded quartzite pebbles; very strongly acid; clear wavy boundary. (0 to 15 inches)

C1--66 to 78 inches; light yellowish brown (10YR 6/4) sandy clay loam; moderate medium prismatic structure parting to weak medium subangular blocky; friable; very few prominent dark yellowish brown (10YR 4/4) clay films on faces of peds and in pores; common fine distinct strong brown (7.5YR 5/8) masses of iron accumulation throughout, common medium distinct reddish yellow (7.5YR 6/8) masses of iron accumulation throughout, common coarse distinct yellowish brown (10YR 5/6) masses of iron accumulation throughout, and common fine distinct light brownish gray (10YR 6/2) iron depletions throughout; strongly acid; clear wavy boundary.

C2--78 to 88 inches; light brownish gray (10YR 6/2) sandy clay loam; weak coarse prismatic structure parting to moderate coarse subangular blocky; friable; very few prominent grayish brown (10YR 5/2) clay films and very few prominent gray (10YR 5/1) clay films on faces of peds and in pores; few fine prominent strong brown (7.5YR 5/8) masses of iron accumulation throughout, common medium prominent reddish yellow (7.5YR 6/8) masses of iron accumulation throughout, and common medium distinct yellowish brown (10YR 5/6) masses of iron accumulation throughout; strongly acid; clear wavy boundary.

C3--88 to 96 inches; light brownish gray (10YR 6/2) sandy clay loam; weak coarse prismatic structure; firm; very few prominent gray (10YR 6/1) clay films on faces of peds and in pores; few fine distinct brownish yellow (10YR 6/6) masses of iron accumulation throughout; strongly acid.

TYPE LOCATION: Adams County, Illinois; about 1.5 miles west and 1 mile north of Richfield; 600 feet north and 460 feet west of the SE corner, sec. 1, T. 3 S., R. 7 W; USGS Payson topographic quadrangle; lat. 39 degrees 49 minutes 53 seconds N. and long. 91 degrees 7 minutes 45 seconds W.

RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon ranges from 40 to 80 inches. The loess mantle, where present, is less than 20 inches in thickness. The particle-size control section averages 18 to 30 percent clay, 25 to 80 percent fine sand and coarser, and less than 15 percent by volume of gravel.

The upper part of the series control section (A, AP, or E horizon) has properties as follows.

The Ap or A horizon has hue of 10YR, value of 4 or 5, and chroma of 2 to 4. Some uncultivated pedons have moist value of 3 in an A horizon that is less than 7 inches in thickness. The Ap or A horizon typically is sandy loam, fine sandy loam, loam, or silt loam. Clay content averages 10 to 25 percent. Reaction ranges from very strongly acid to moderately acid except pedons that have been limed range to slightly alkaline.

The E horizon, where present, has hue of l0YR, value of 4 to 6, and chroma of 2 to 6. It typically is sandy loam, fine sandy loam, or loam, and less commonly is silt loam. Clay content averages 5 to 20 percent. Reaction ranges from moderately acid to very strongly acid except pedons that have been limed range to neutral.

Some pedons have a BE horizon as much as 6 inches in thickness.

The middle part of the series control section (Bt, 2Bt, BC or 2BC horizon) has properties as follows.

The Bt horizon has hue of l0YR or 7.5YR, value of 4 to 6, and chroma of 3 to 6. Redoximorphic features have hue of 10YR, 7.5YR, or 2.5Y value of 4 to 6, and chroma of 2 to 8. The upper 10 inches of the argillic horizon does not have redoximorphic depletions with chroma of 2 or less. The Bt horizon is sandy clay loam, clay loam, loam, sandy loam, or fine sandy loam. Some pedons have silty clay loam when the upper horizons formed in loess. Some pedons are stratified. Clay content averages 18 to 30 percent. Reaction is very strongly acid or strongly acid, some pedons contain a subhorizon in the upper part that ranges from moderately acid to neutral.

The BC horizon, where present, has properties similar to the Bt horizon.

The lower part of the series control section (C or 2C horizon) has properties as follows.

The C horizon has hue of 7.5YR, l0YR, 2.5Y, or 5Y, value of 4 to 7, and chroma of 1 to 8. It commonly is stratified in color or texture or both. Textures include sandy loam, loamy sand, sand, loam, silt loam, or sandy clay loam. Clay content averages 5 to 25 percent. Reaction ranges from moderately acid to very strongly acid.

COMPETING SERIES: These are the Beech, Blocher, Cadmus, Dormont, Funkstown (T)MD, Glenhall, Kidami, Miami, Octagon, Pevely, Rainsville, Rawson, Richland, Royerton, Shawtown, Summitville, Vaughnsville, and Wapahani. These competing series did not form in cretacious deposits. Beech soils average 15 to 35 percent rock fragments in the particle-size control section. Blocher and Dormont soils average less than 25 percent sand in the particle-size control section. In addition, Dormont soils have a paralithic contact at depths below 48 inches. Cadmus soils have carbonates below depths of 24 inches. Funkstown (T) soils have limestone residuum below a depth of 25 inches. Glenhall soils have more than 15 percent rock fragments in the 2B horizon and are less acid in the lower part of the series control section. Kidami soils are less acid than moderately acid in the lower part of the series control section. Miami, Octagon and Royerton soils have carbonates at depths below 20 inches. Pevely soils have a lithic contact at depths below 20 inches. Rainsville soils have carbonates at depths below 45 inches. Rawson soils have more than 35 percent clay in the lower part of the series control section. Richland soils have more than 20 percent rock fragments in the lower part of the series control section. Shawtown soils have carbonates at depths below 36 inches. Summitville soils have a paralithic contact below a depth of 40 inches. Vaughsville soils have hue redder than 7.5YR in the upper part of the argillic horizon. Wapahani soils are less than 20 inches to the base of the argillic horizon and have carbonates at depths below 8 inches.

GEOGRAPHIC SETTING: El Dara soils are exposed on side slopes of a highly dissected upland ridge. They are included with the Dissected Till Plains geographic section. Slope gradients range from 5 to 60 percent. These soils formed in stratified loamy and sandy materials of Cretaceous age. Some pedons formed in as much as 20 inches of loess. Some of the area is believed to be unglaciated. Mean annual temperature ranges from 5l to 55 degrees F, mean annual precipitation ranges from 32 to 36 inches, frost free period ranges from 160 to 190 days, and elevation ranges from 650 to 850 feet above sea level.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Atlas, Bunkum, Clarksdale, Downsouth, Emery, Gosport, Ipava, Keomah, Keswick, Lindley, Passport, Rushville, Timewell, Virden, Wakenda, and Winfield soils. Atlas soils average more than 35 percent clay in the particle-size control section, formed in Sangamon paleosol of Illinoian age, are somewhat poorly drained, and are on similar positions as El Dara soils. Bunkum and Emery soils formed in loess and the underlying pedisediment, average less than 25 percent sand in the particle-size control section, are somewhat poorly drained, and are found upslope from the El Dara soils. Clarksdale, Ipava, Keomah, and Timewell soils are somewhat poorly drained, formed in loess, average more than 35 percent clay in the particle-size control section, and are found above El Dara soils on less sloping areas. Downsouth, Winfield and Wakenda soils formed in loess, average less than 15 percent sand in the particle-size control section, and are found above El Dara soils on less sloping areas. In addition, Wakenda soils are well drained. Gosport soils average more than 35 percent clay in the particle-size control section, formed in shale residuum, have a paralithic contact at depths below 20 inches, are well drained, and are on slopes below the El Dara soils. Keswick soils average more than 35 percent clay in the particle-size control section, are on similar slopes below El Dara soils, and formed in Pre-Illinoian age glacial till. Lindley soils are on similar or steeper slopes, typically at lower elevations, are well drained, and formed in Pre-Illinoian age glacial till. Passport soils formed in loamy pedisediments and in Illinoian glacial till that contains a strongly developed paleosol, and are somewhat poorly drained. Rushville and Virden soils formed in loess, average more than 35 percent clay in the particle-size control section, and are above El Dara soils.

DRAINAGE AND PERMEABILITY: Moderately well drained Permeability is moderate. The potential for surface water runoff is high or very high. The seasonal apparent high water table is at a depth of 2.0 to 3.5 feet below the surface during the spring.

USE AND VEGETATION: Many of the less sloping areas are used for pasture or meadow; but some of those areas are used for cultivated crops. Most of the steep areas are used for woodland. Native vegetation is deciduous forest, mainly oak and hickory. El Dara soils are subject to gully erosion.

DISTRIBUTION AND EXTENT: Western and Central Illinois. Extent is small.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana

SERIES ESTABLISHED: Adams County, Illinois, l974.

REMARKS: Classification adjusted to agree with lST Issue #17 on 23 Aug 94 by CLG. Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface of the soil to a depth of 6 inches (Ap horizon); argillic horizon - the zone from a depth of 6 to 61 inches (Bt1, Bt2, Bt3, Bt4, Bt5, Bt6, and Bt7 horizons). Oxyaquic subgroup based on soil saturation above a depth of 40 inches. Well drained El Dara soils will be included in the Oxyaquic subgroup.

Series relocated and adjusted for Adams County Update 5/14/97 by RDC-RT Changes made to location, description, geology, competing series, geographically associated soils, drainage, and permeability.

It is difficult to differentiate the properties of the lower part of the modern solum from those of the older materials. Development can go down several feet.

Note: El Dara soils may range to somewhat poorly or poorly drained if a paleosol is present near the surface. As slope and erosion increase, coarse-loamy and sandy textures become dominant and may warrant new series because of the uniqueness of the Cretaceous aged Baylis formation in western Illinois. The Baylis formation resembles the Dakota formation in western Iowa and is composed of layered sand, pink and gray clays, and gravel members. A small area near Wedron, Illinois may also have this type of formation.

El Dara was formerly identified as being formed in outwash materials. Areas mapped El Dara outside Cretaceous boundaries should be investigated during MLRA update activities. Many of the geographically associated soils in the Cretaceous areas are formed in deposits not recognized in their respective Official Series Descriptions. Clayey and very sandy soils are considered unnamed inclusions in mapping units of the El Dara series. There is not sufficient acreage for separate series in this geologic sequence to represent new series.

ADDITIONAL DATA: Data for a different El Dara pedon is identified by laboratory numbers 22641-22649. It is on file at the NRCS MLRA Office Region 11.


National Cooperative Soil Survey
U.S.A.