Claybanks Forest is a 56-acre preserve featuring rock outcrops with remarkable, internationally known Devonian fossils. It is located 5 miles southwest of Nora Springs in eastern Cerro Gordo County. Consisting of three separate parcels of land, it was purchased by the Cerro Gordo Conservation Board in 1966. The site was dedicated as a geological state preserve in 1982.
This preserve is known historically as “Hackberry Grove.” The name “Claybanks” refers to the light-colored soft limey shales of the 375- million-year-old rocks bearing the fossils. These outcrops of soft shale and limestone found along the banks of the Winnebago River (originally called Lime Creek) are where the “Lime Creek Formation” was first described in the geologic literature and thus represent the “type-locality” for this formation