County: Ottawa

Date: July 1963

Photographer: Grace Muilenburg/KGS

Place Name: Rock City

Short description: Crossbedded sandstone at Rock City in Ottawa County. Sandstone spheres up to 20 feet in diameter cover an area roughly the size of two football fields at Rock City. Known as concretions, the spheres weathered out of a sandstone layer in the Dakota Formation. The sandstone formed mainly from sand deposited along the edge of a sea that covered the western half of Kansas during the Cretaceous Period.

Hi-Resolution Version

Credit: This photo may be reproduced for non-commercial and educational purposes. When using this photo in a publication, website, or presentation, please credit Kansas Geological Survey. For information about use for commercial purposes, please contact the KGS editor.