LOCATION AUREOLA IAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Typic Hapludolls
TYPICAL PEDON: Aureola loam on a convex northeast-facing slope of 3 percent - cultivated. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 9 inches; very dark brown (10YR 2/2) loam, dark grayish brown (10YR 4/2) dry; weak very fine granular structure; friable; neutral; abrupt smooth boundary.
A--9 to 14 inches; very dark brown (10YR 2/2) and very dark grayish brown (10YR 3/2) loam, brown (10YR 4/3) dry; weak very fine granular structure; friable; neutral; gradual smooth boundary. (Combined thickness of the A horizons is 10 to 18 inches.)
BA--14 to 19 inches; dark brown (10YR 3/3) loam, brown (10YR 4/3) dry; very dark grayish brown (10YR 3/2) coatings on faces of peds; weak very fine subangular blocky structure; friable; neutral; gradual smooth boundary. (0 to 7 inches thick)
Bw1--19 to 26 inches; yellowish brown (10YR 5/4) loam; dark yellowish brown (10YR 4/4) coatings on faces of peds; weak very fine and fine subangular blocky structure; friable; neutral; gradual smooth boundary.
Bw2--26 to 33 inches; yellowish brown (10YR 5/6) sandy loam; weak fine and medium subangular blocky structure; very friable; neutral; abrupt smooth boundary. (Combined thickness of the Bw horizons is 10 to 25 inches.)
2C1--33 to 48 inches; brownish yellow (10YR 6/6) loamy fine sand; few fibrous roots; strongly alkaline; violent effervescence; clear wavy boundary.
2C2--48 to 60 inches; olive yellow (2.5Y 5/6) loamy fine sand; few fibrous roots; strongly alkaline; violent effervescence.
TYPE LOCATION: Floyd County, Iowa; about 3 miles east and 1 mile south of Marble Rock; 2,415 feet north and 190 feet east of the southwest corner, sec. 13, T. 94 N., R. 17 W.
RANGE IN CHARACTERISTICS: Thickness of the loamy surficial sediments over sandy material weathered from calcareous sandstone is 20 to 40 inches. Thickness of the solum and depth to carbonates is 20 to 40 inches. This coincides closely with the thickness of the loamy sediment. The mollic epipedon is 10 to 20 inches thick unless eroded.
The A horizon typically is very dark brown (10YR 2/2) or very dark grayish brown (10YR 3/2) but includes black (10YR 2/1). It typically is loam or sandy loam but some is silt loam. It is neutral or slightly acid. An AB horizon is present in some pedons. It is very dark grayish brown (10YR 3/2) or dark brown (10YR 3/3).
The Bw horizon has value of 4 to 6, and chroma of 3 to 6. The Bw horizon typically is loam or sandy loam with a clay content of 10 to 15 percent.
When crushed, the 2C horizon ranges from loamy fine sand to sand. The 2C horizon has hue of 10YR or 2.5Y, value of 5 to 7, and chroma of 3 to 6.
COMPETING SERIES: These are the Becker, Bertram, Bolan, Carmi, Dickinson, Elrick, Etter, Flagler, Lowlein, Olin, Ridgeport, Wadenill, and Zenor soils. A similar series is the Rossfield soils. Becker, Ridgeport, and Zenor soils have more gravel in the lower part of the control section. Bolan, Dickinson, Elrick, Etter, and Flagler soils have carbonates deeper in the control section or are noncalcareous throughout. Carmi soils are noncalcareous and have more gravel throughout the control section. Lowlein, Olin and Wadenill soils have loamy textures in the control section below 40 inches. Bertram soils have a lithic contact at depths between 20 and 40 inches. Etter soils are more acid in the lower part of the control section.
GEOGRAPHIC SETTING: These soils are on nearly level to gently sloping ridge crests and gently sloping to strongly sloping side slopes. They formed in 20 to 40 inches of loamy surficial sediment and sandy material weathered from calcareous sandstone. In some areas red Cretaceous clay is at a depth of 40 inches to 60 inches or more. Mean annual temperature ranges from 44 to 48 degrees F, and mean annual precipitation ranges from 28 to 34 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dodgeville, Floyd, Jacwin, Mottland, and Ostrander soils. Dodgeville soils are underlain by a lithic contact with limestone at 20 to 40 inches. Floyd soils formed in glacial sediments lower on the landscape. Jacwin soils are underlain by shale and are lower on the landscape. Mottland soils are shallow to the underlying sandstone. Ostrander soils typically are higher on the landscape and formed in loamy surficial sediment and underlying materials of glacial origin.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate in the loamy surficial sediment and rapid in the underlying sandy material. Surface runoff is slow to medium.
USE AND VEGETATION: Most areas are used primarily for growing corn and soybeans. Native vegetation was prairie grasses.
DISTRIBUTION AND EXTENT: North central Iowa and possibly northeastern Iowa and southeastern Minnesota. They are inextensive.
MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Floyd County, Iowa, 1989. The name is taken from a small, unincorporated village in Floyd County.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon--the zone from the surface to a depth of 19 inches (Ap, A, and BA horizons); Cambic horizon--the zone from 14 to 33 inches (BA, Bw1, and Bw2 horizons); udic moisture regime.