Tag Archives: Stanley

GeoPic of the Week: Tilted rock layers at Cossatot Falls, Cossatot River State Park – Natural Area

Tilted Rock at Cossatot Falls

Tilted rock layers at Cossatot Falls, Cossatot River State Park – Natural Area

The Cossatot River is located in the Ouachita Mountains physiographic province in south-western Arkansas.  Notice the tilted rock layers.  Geologists informally use the term dipping to describe these rock layers.  The majority of rocks in the Ouachita Mountains are dipping and sometimes almost vertical.  Why?  The Ouachita Mountains Region contains sedimentary rocks that were originally deposited as flat-lying layers.  Later on, these rocks were uplifted and compressed northward due to a major mountain building process called the Ouachita Orogeny.  This caused the rock layers to be tilted.  The rocks exposed at Cossatot Falls are sandstones in the Mississippian Stanley Formation.