The Geology P.A.G.E.: Geology of the National Parks in Pictures - New River Gorge National Park & Preserve

Monday, November 27, 2023

Geology of the National Parks in Pictures - New River Gorge National Park & Preserve

My next post about the Geology of the National Parks Through Pictures is from my undergraduate years when we traveled the national parks during spring break.

You can find more Geology of the National Parks Through Pictures as well as my Geological State Symbols Across America series at my website Dinojim.com.

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New River Gorge National Park & Preserve

Another park that is within the Appalachian Mountains, the New River Gorge has a similar geological history as other nearby parks like Shenandoah National Park to the east and the Great Smoky Mountains to the south. It also traverses some of the same rock types as the Gauley River National Recreation Area a short distance to the north, however since the New River Gorge is much larger and deeper than the Gauley River valley, the rocks exposed are slightly older (although they also overlap).

The New River Gorge cuts through Carboniferous Age deposits from the Upper Mississippian age Bluefield Formation (~325 million years old) up through the Middle Pennsylvanian Allegheny Formation (~312 million years old).

Geology of the New River Gorge National Park & Preserve. Map courtesy of the NPS.

The different formations are groups of rocks made up of members that were deposited in similar environments. Although the water levels fluctuate up and down during this time interval, overall North America is moving towards Africa in this time period as the Iapetus Ocean was closing up towards the east. Eventually North America will meet up with Africa to form the supercontinent Pangea, but we haven't gotten there yet when these rocks were deposited.

Geological map units for the New River Gorge National Park & Preserve. Courtesy of the NPS.

The rock units here, as well as at Gauley River NRA, dip towards northwest in a direction that essentially follows the course of the river. One of the oldest formations, the Hinton Formation, was deposited along the coast, with both marine and freshwater deposits represented. It is made up of shales and siltstones, with lesser amounts of sandstones and limestones. It gets up to 1,000 feet thick within the gorge.

Geologic Profile of the New River Gorge. Image courtesy of WVGES.

Above the Hinton Formation, the Bluestone Formation is what is known as a regressive sequence, where the sea level slowly went downwards until there is a paleosol (ancient soil) deposited before the Pocahontas Formation starts to be deposited. The paleosol represents an unconformity, which is a buried erosional surface, and signifies the transition from the Mississippian to the Pennsylvanian. Above the Pocahontas Formation is the New River Formation, which is partially seen at the Gauley River NRA. This again represents a coastal environment and the last coastal environment deposited within the region.

The New River itself is often designated the "second oldest river in the world," however this is difficult thing to actually determine. We know that the oldest rocks that the New River erodes through are ~310 million years old, so the river must be younger than that.

It is also estimated that the river is at least 3 million years old based on glacial evidence that the New River follows the same course as the pre-glacial Teays River a river that used to flow towards the northwest and eventually was the ancestor to the lower reaches of the Illinois River. The Teays River, and eventually the New River, is the only river to cut across the Appalachian Mountains. This is because it predated the mountains and was able to cut down through them as they were lifted up, much like the Colorado River cutting out the Grand Canyon or the Black Canyon of the Gunnison. Estimates for the age of the New River therefore fluctuate between 3 and 310 million years, quite a variance.

Along the New River Gorge, with the steep sided cliffs due to the abundance of sandstone deposits forming ledges, there are a number of picturesque waterfalls. I believe this is Cathedral Falls, which starts far above me in the picture, tumbling over the New River Formation's Upper Nuttall Sandstone.

But while there are some of the largest waterfalls in West Virginia within the New River Gorge, there are also smaller waterfalls, that flow down many of the shale deposits along the gorge's depth.