LOCATION RILEY ILEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, mesic Fluvaquentic Hapludolls
TYPICAL PEDON: Riley silty clay loam - nearly level on a low ridge in a cultivated field at an elevation of about 470 feet above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) silty clay loam, gray (10YR 5/1) dry; moderate fine granular structure; firm; common fine roots throughout; very dark gray (10YR 3/1) organic coatings on faces of peds; slightly acid; abrupt smooth boundary.
A--7 to 13 inches; very dark grayish brown (10YR 3/2) silty clay loam, gray (10YR 5/1) dry; moderate fine and medium subangular blocky structure; firm; common fine roots throughout; moderately acid; abrupt smooth boundary. (Combined thickness of the A horizon is 10 to 18 inches.)
Bw1--13 to 19 inches; dark grayish brown (10YR 4/2) silty clay loam; weak coarse subangular blocky structure; firm; common fine roots throughout and common very fine and fine roots in cracks; common very fine and fine continuous tubular pores; very few distinct patchy very dark grayish brown (10YR 3/2) organic coatings on faces of peds; many fine distinct irregular brown (7.5YR 4/3) masses of iron accumulation throughout; moderately acid; clear smooth boundary.
Bw2--19 to 27 inches; grayish brown (10YR 5/2) loam; moderate coarse subangular blocky structure; firm; common very fine and fine roots in cracks; common very fine and fine continuous tubular pores; many fine and medium distinct irregular dark yellowish brown (10YR 3/6) masses of iron accumulation throughout; moderately acid; clear smooth boundary. (Combined thickness of the Bw horizon is 6 to 24 inches.)
2C1--27 to 36 inches; brown (10YR 4/3) loamy sand; weak coarse subangular blocky structure; friable; few fine faint dark yellowish brown (10YR 4/4) masses of iron accumulation throughout; moderately acid; clear smooth boundary. (12 to 36 inches thick)
2C2--36 to 60 inches; brown (10YR 5/3) sand; single grain; loose; neutral; clear smooth boundary.
2C3--60 to 80 inches; 60 percent brown (10YR 5/3) and 40 percent pale brown (10YR 6/3) sand; single grain; loose; neutral.
TYPE LOCATION: Adams County, Illinois; about 2 miles west of the village of Marblehead; 1595 feet east and 340 feet south of the northwest corner of sec. 2, T. 3 S., R. 9 W.; USGS Quincy Southwest topographic quadrangle; lat. 39 degrees 50 minutes 35 seconds N. and long. 91 degrees 24 minutes 30.2 seconds W.
RANGE IN CHARACTERISTICS: The depth to the base of the cambic horizon typically is 18 to 28 inches, but ranges to 40 inches. The mollic epipedon ranges from 10 to 20 inches in thickness. Sand coarser than very fine sand is between 15 and 60 percent in the particle size-control section. Reaction is moderately acid to slightly alkaline in the solum and moderately acid to moderately alkaline in the underlying material.
The upper part of the series control section (A or Ap horizon) has hue of 10YR, value of 2 or 3, and chroma of 1 to 3. Texture is silty clay loam, clay loam, silt loam or loam.
The middle part of the series control section (Bw horizon that formed in loamy alluvium) has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 2 to 4. Redoximorphic features have hue of 7.5YR or 10YR, value of 2 to 6 and chroma of 1 to 6. Texture is silty clay loam, clay loam, sandy clay loam, loam, or silt loam. It averages between 24 and 35 percent clay and between 20 and 65 percent sand.
The lower part of the series control section (2C horizon that formed in sandy alluvium) has value of 4 to 7, and chroma of 2 to 4. Redoximorphic features have a hue of 7.5YR or 10YR, value of 2 to 6 and chroma of 1 to 6. Texture commonly is loamy sand or sand, and contains lenses or strata of silt loam, loam, fine sandy loam, loamy fine sand, coarse sand or silty clay loam. The average texture of the 2C horizon is loamy fine sand or coarser. Clay content averages 2 to 10 percent and sand content ranges from 20 to 90 percent. Coarse sand averages more than 35 percent by volume.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Riley soils are on nearly level to undulating low rises on flood plains. Slope gradients are 0 to 3 percent. These soils formed in moderately fine textured or medium textured aluvium, 16 to 40 inches in thickness, over sandy waterlaid sediments. Mean annual temperature varies from 50 degrees to 57 degrees F., and mean annual precipitation varies from 38 to 45 inches, frost free period ranges from 170 to 200 days, and elevation ranges from 340 to 1020 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beaucoup, Fults, Gorham, Landes and Ware soils. The poorly drained Beaucoup, Fults and Gorham are on lower-lying parts of the flood plain. Landes and Ware soils are on similar or slightly higher parts of the flood plain nearby and are well or moderately well drained.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. The potential for surface water runoff is low or medium. Permeability is moderate in the solum and rapid in the underlying sediments. The seasonal high water table is 1.0 foot to 2.0 feet below the surface from January to May in most years.
USE AND VEGETATION: Most areas of Riley soils are cropped. Corn, soybeans and wheat are the principal crops. Native vegetation dominantly is deciduous trees.
DISTRIBUTION AND EXTENT: Illinois, mainly on the bottomlands of the major rivers. Extent is moderate in MLRA's 108 and 115.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Jackson County, Illinois, 1929.
REMARKS: Diagnostic horizons and features recognized in this pedon are: Mollic epipedon - the zone from the surface of the soil to a depth of 13 inches (Ap and A horizons) Cambic horizon - the zone from approximately 13 to 27 inches (Bw1 and Bw2 horizons) Fluvaquentic Hapludoll feature - irregular decrease in organic carbon at the strongly contrasting particle-size break at a depth of 27 inches and matrix color with chroma of 2 in the zone 15 cm thick immediately below the mollic epipedon.