 The local rock formations are some of the most distinctive in the state of Oklahoma.Just north of Broken Bow, sedimentary rock has been thrust upward due to an ancient collision of the North American and South American Plates, forming what is now the Ouachita Mountains.Evidence of what is called the Ouachita orogeny can be seen all over the park, where some layers of rock can be seen tilted up at angles of about sixty-degrees.