Ouachita Mountains

The Ouachita Mountains are a mountain range located in Arkansas and Oklahoma. Heavily eroded ridges extend into Texas, and the range's subterranian roots may extend as far as central Texas, or beyond it to the current location of the Marathon Uplift.

The Ouachita (pronounced "wah-shi-tah") Mountains are fold mountains like the Appalachian Mountains to the east. During the Pennsylvanian part of the Carboniferous period, about 300 million years ago, the coastline of the Gulf of Mexico ran through the central parts of Arkansas. As the South American plate drifted northward, a subduction zone was created in this region. The South American oceanic crust was forced underneath the less-dense North American continental crust. Geologists call this collision the Ouachita orogeny. The collision buckled the continental crust, producing the fold mountains we call the Ouachitas. At one time the Ouachita Mountains were very similar in height to the current elevations of the Rocky Mountains. Due to the Ouachitas' age, the craggy tops have eroded away leaving the low formations that used to be the heart of the mountains.

Unlike most other mountain ranges in the United States, the Ouachitas run east and west rather than north and south. This unique formation has been known to cause confusion to pilots flying over the region. Also, Ouachitas are distinctive in that volcanism, metamorphism, and intrusions are notably absent throughout most of the system.

The Ouachita Mountains contain the Ozark National Forest and Hot Springs National Park as well as numerous state parks and scenic byways.

External link

• Geology of the Ouachita Mountains, from a rockhound's perspective.