Cannonball Concretions – Theodore Roosevelt National Park, North Dakota

Over thousands of years, the Little Missouri River has shaped the soft sedimentary layers of the Great Plains—showcasing some of its best work, are the badlands and geological formations found within Theodore Roosevelt National Park, North Dakota.

The amazing colors and shapes of the theatrical Badlands aside, the large spherical boulders known as Cannonball Concretions definitely steal the show—these “cannonballs” were formed when sand grains from an ancient river deposit were cemented together by minerals dissolved in ground water, their perfectly round shape a beautifully stark contrast to the jagged, deeply eroded ridges of the surrounding badlands.

Discovering the Cannonball Concretions for yourself is easy, simply park at the designated pullout and hike a few feet along the Buckhorn Trail—this 11.3 mile loop trail also passes through a prairie dog town with no shortage of residents, including the occasional bison.