Red River Gorge Geological Area
400 Million Years of Geologic History
The core of the Red River Basin is the ‘Gorge,’ a canyon system within Daniel Boone National Forest in eastern Kentucky that was designated a National Geologic Area by the US government.
The geologic history of the Red River watershed spans over 400 million years, and starts with the deposition of sediments in marine and then river delta environments.
These sediments were compacted into rocks that were then shaped and weathered by natural elements over millions of years.
Chemical changes over time led to a unique collection of holes, tubes, and plates that provide interesting and challenging handholds for climbers and have elevated the Corbin Sandstone to a worldwide climber destination.
Recent weathering processes have exhumed rocks that have broken along joints into sheer cliffs, majestic arches, and large amphitheaters.
Examining the geologic processes in three phases
Bedrock Formation: The first phase begins with the accumulation of sediments in an ancient coastal river plain starting about 340 million years ago. The sands and other sediments deposited at this time are the materials that have since hardened to form the bedrock of the area.
Diagenesis: Diagenesis is the process by which the sediments were buried and turned into rock. The process began when sediments were first buried, and is ongoing today as groundwater flows through rock pores and continues to modify the rocks’ internal structure. Economically important oil and iron deposits also resulted from diagenetic processes.
Geomorphology: The final geological phase is the erosion of the bedrock into landforms such as the cliffs and arches that we see today. This formation of landforms is known as ‘geomorphology.’
Are they arches or bridges?
The Natural Bridge is an arch; Whittleton Arch is a bridge, and Henson’s and Moonshiner’s Arches are neither.
If you are confused, you are not alone.
Geologists have generally chosen the words “arch” and “bridge” to refer to landforms made by different processes, rather than to the actual shape of the structures.
Geologists define “natural bridges” as structures eroded into existing rock by running streams. “Natural arches” are structures weathered into exposed rock without streams.
