Tuscola Anticline

Part of the La Salle Anticlinorium

Location

Coles, Douglas, and southern Champaign Counties (E,F-7)

References

Bell 1943, Clegg 1959, Bristol and Prescott 1968, Buschbach and Bond 1974

Description

The Tuscola Anticline is the largest anticline in Illinois in terms of area and amount of closure. As contoured on top of the Galena Group (Bristol and Buschbach 1973), the Tuscola Anticline has closure of more than 700 feet (210 m). The enclosed area extends 25 miles (40 km) from southern Champaign County almost to the southern border of Douglas County and is 10 miles (16 km) wide in places. The southward-plunging nose extends well into Coles County. On the western limb, the top of the Galena (Trenton) Group drops 2,500 feet (760 m) in 3 to 4 miles (5-6.5 km). This is the greatest structural relief found along the La Salle Anticlinorium. In Illinois, only the Ste. Genevieve and Shawneetown Fault Zones produce greater vertical offsets.

The Tuscola Anticline lies along the eastern uplifted side of the Charleston Monocline that runs from southern Lawrence to southern Champaign County.

Like the rest of the La Salle Anticlinorium, the Tuscola Anticline underwent major uplift very late in the Mississippian Period and early in the Pennsylvanian Period. As a result, structural relief is considerably less on Pennsylvanian than on older horizons. Pennsylvanian rocks surround the anticline but have been eroded from its crest. Silurian rocks subcrop beneath glacial drift at the apex of the fold.

Hayes Oil Field was developed in the Galena (Trenton) on the Tuscola Anticline. About 147,000 barrels were produced between 1962 and 1971. In 1970 a gas storage field, developed on the anticline, used Mt. Simon Sandstone (Cambrian) as the reservoir.