LOCATION ROOKS ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Argiudolls
TYPICAL PEDON: Rooks silty clay loam - on a nearly level slope in a cultivated field at an elevation of 200 meters (655 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 23 cm (0 to 9 inches); black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; moderate fine granular structure; common fine roots; neutral; abrupt smooth boundary. [20 to 25 cm (8 to 10 inches) thick]
AB--23 to 38 cm (9 to 15 inches); very dark grayish brown (10YR 3/2) silty clay loam, gray (10YR 5/1) dry; weak fine subangular blocky structure parting to moderate fine granular; friable; few very fine roots; many faint black (10YR 2/1) organic coatings on faces of peds; neutral; clear smooth boundary. [0 to 20 cm or (0 to 8 inches) thick]
Bt1--38 to 56 cm (15 to 22 inches); brown (10YR 4/3) silty clay loam; moderate fine prismatic structure parting to moderate fine angular blocky; friable; few very fine roots; many faint very dark gray (10YR 3/1) organic coatings on faces of peds; few faint very dark grayish brown (10YR 3/2) organo-clay films on faces of peds; common faint dark grayish brown (10YR 4/2) clay films on faces of peds; common fine faint grayish brown (10YR 5/2) iron depletions in the matrix; neutral; clear smooth boundary.
Bt2--56 to 76 cm (22 to 30 inches); grayish brown (10YR 5/2) silty clay loam; weak medium prismatic structure parting to moderate fine angular blocky; friable; few very fine roots; common faint very dark gray (10YR 3/1) organic coatings on faces of peds; few faint very dark grayish brown (10YR 3/2) organo-clay films on faces of peds; common faint dark grayish brown (10YR 4/2) clay films on faces of peds; common fine prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; common fine faint gray (10YR 5/1) iron depletions in the matrix; neutral; clear smooth boundary. [Combined thickness of the Bt horizons is 36 to 56 cm (14 to 22 inches).]
2Btk1--76 to 97 cm (30 to 38 inches); grayish brown (10YR 5/2) silt loam; weak medium prismatic structure parting to weak fine angular blocky; friable; few very fine roots; few faint gray (10YR 5/1) clay films on faces of peds; few fine black (7.5YR 2.5/1) iron-manganese oxide accumulations throughout; common fine light gray (10YR 7/2) moderately cemented calcium carbonate concretions throughout; many medium prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; slightly effervescent; slightly alkaline; clear smooth boundary.
2Btk2--97 to 114 cm (38 to 45 inches); gray (10YR 6/1) and yellowish brown (10YR 5/6) silty clay loam; weak medium prismatic structure; friable; common faint gray (10YR 5/1) clay films on faces of peds; few fine black (7.5YR 2.5/1) iron-manganese oxide accumulations throughout; common fine light gray (10YR 7/2) moderately cemented calcium carbonate concretions throughout; strongly effervescent; moderately alkaline; clear smooth boundary. [Combined thickness of the 2Btk horizons is 20 to 38 cm (8 to 15 inches).]
3BCk--114 to 130 cm (45 to 51 inches); grayish brown (2.5Y 5/2) and light olive brown (2.5Y 5/4) silty clay loam; weak medium prismatic structure; firm; common faint gray (10YR 5/1) pressure faces on vertical faces of peds; common medium light gray (10YR 7/2) moderately cemented calcium carbonate concretions throughout; 1 percent gravel; strongly effervescent; moderately alkaline; clear smooth boundary. [0 to 20 cm (0 to 8 inches) thick]
3C--130 to 152 cm (51 to 60 inches); grayish brown (2.5Y 5/2) and light olive brown (2.5Y 5/4) silty clay loam; massive; firm; many faint gray (2.5Y 5/1) pressure faces on vertical cleavage planes; 3 percent gravel; strong effervescent; moderately alkaline.
TYPE LOCATION: Livingston County, Illinois; about 3.2 kilometers (2 miles) southwest of Long Point; 119 meters (390 feet) east and 716 meters (2,350 feet) south of the northwest corner of section 18, T. 29 N., R. 3 E. USGS Dana, Illinois topographic quadrangle; lat. 40 degrees 58 minutes 47 seconds N., and long. 88 degrees 55 minutes 46 seconds W., UTM Zone 16, 337675 Easting and 4538315 Northing; NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of soil development ranges from 102 to 132 cm (40 to 55 inches). Depth to the silty lacustrine sediments and carbonates is 64 to 102 cm (25 to 40 inches). The particle-size control section averages between 25 and 35 percent clay.
The Ap or A horizon has a hue of 10YR, value of 2 or 3, and chroma of 1 or 2. It is silty clay loam or silt loam. It is slightly acid to neutral.
Some pedons have a BA horizon instead of an AB horizon.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 through 6, and chroma of 2 through 6. It is commonly silty clay loam, but some subhorizons include silty clay. It is moderately acid to neutral. Sand content ranges from 1 to 10 percent, and clay content ranges from 27 to 45 percent.
The 2Btk horizon has hue of 10YR or 2.5Y, value of 4 through 6, and chroma of 1 through 6. It commonly is silt loam, but some pedons have thin subhorizons of silty clay loam or loam. It is slightly alkaline or moderately alkaline and contains free carbonates. Sand content ranges from 5 to 15 percent, and clay content ranges from 5 to 30 percent.
Some pedons have a 2BCk horizon.
The 3BCk or 3C horizon has hue of 10YR, 2.5Y or 5Y, value of 4 through 6, and chroma of 1 through 6. It is silty clay loam or silty clay. It is slightly alkaline or moderately alkaline and contains free carbonates. Sand content ranges from 5 to 15 percent, and clay content ranges from 27 to 45 percent. Gravel content ranges from 1 to 5 percent.
COMPETING SERIES: These are the Arrowsmith, Bearpen, Brenton, Edwardsville, Elburn, Grundelein, Hacreek, Harco, Higginsville, Keller, Lafayette, Lawndale, Lisbon, Lismod, Loran, Mundelein, Muscatune, Raub, Rowley, and Shannondale soils. Arrowsmith, Brenton, Edwardsville, Elburn, Harco, Lawndale, Lisbon, Lismod, and Mundelein soils contain less than 27 percent clay in the lower part of the series control section. Bearpen, Hacreek, Higginsville, Keller, Lafayette, and Shannondale soils do not have carbonates above a depth of 102 cm (40 inches). Grundelein and Rowley soils average more than 75 percent sand in the lower part of the series control section. Loran soils have a paralithic contact within a depth of 152 cm (60 inches). Muscatune soils have less then 5 percent sand in the series control section. Raub soils have more than 15 percent sand in the lower one-third of the series control section.
GEOGRAPHIC SETTING: Rooks soils are on nearly level areas of till floored lake plains of Wisconsinan age. Slope ranges from 0 to 5 percent. The soils formed in 64 to 102 cm (25 to 40 inches) of loess over 25 to 51 cm (10 to 20 inches) of silty, calcareous, lacustrine sediments over calcareous till. Mean annual air temperature ranges from 7 to 11 degrees C (45 to 52 degrees F), mean annual precipitation ranges from 813 to 1065 mm (32 to 42 inches), frost free days is 140 to 190 days, and the elevation ranges from 180 to 270 meters (590 to 885 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ashkum, Chenoa, Graymont, Harco, and Patton soils. The poorly drained Ashkum soils, the somewhat poorly drained Chenoa soils, and the moderately well drained Graymont soils formed in loess and the underlying till and do not have the silty, lacustrine sediments. The somewhat poorly drained Harco soils and the poorly drained Patton soils formed in loess and silty lacustrine sediments and do not have till within 152 cm (60 inches).
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. An intermittent perched seasonal high water table is at a depth of 30 to 61 cm (1.0 to 2.0 feet) at some time between January and May in most years. The potential for surface runoff is low or medium. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers per second) in the loess, moderately high (1.41 to 4.23 micrometers per second) in the lacustrine sediments, and moderately low or moderately high (0.42 to 1.41 micrometers per second) in the till. Permeability is moderate in the loess, moderately slow in the lacustrine sediments, and slow in the till.
USE AND VEGETATION: Most areas are cultivated. Corn, soybeans, small grain, and meadow are the principle crops. Native vegetation was prairie grass.
DISTRIBUTION AND EXTENT: Central and east-central Illinois. Extent is small.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Livingston County, Illinois, 1990.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from 0 to 38 cm (0 to 15 inches) (Ap and AB horizons); argillic horizon - the zone from 38 to 114 cm (15 to 45 inches) (Bt1, Bt2, 2Btk1, and 2Btk2 horizons); udic moisture regime; the fine to coarse silt ratios indicate stratification in the 2Bt horizons.