Image for the Asking: How Old Is Old?

Image for the Asking: How Old Is Old?

Don McGowan

Story and image by Don McGowan

“How high is up?” This is a question that children have harangued adults about unceasingly over the years. It’s one that can seem sublimely foolish—at least as most of those adults would see it.

There is, too, a second inquiry which often accompanies the first: “How old is old?” And for someone like me, this is much more sensible than a question about altitude or elevation.

Having arrived at the ripe age of 75, I deem that my three-quarters of a century qualify me as old; yet, all those years hardly amount to a drop in the proverbial bucket when it comes to the age of a single Smokies rock or rock strata.

These are ancient, almost beyond counting, these “Mountains of the Blue Mist,” these Shaconage (in the Cherokee language). But before we launch into thinking about how old “old” is, let’s return to a lesson we all learned in high school geology. Earth is comprised of three primary types of rock: igneous, metamorphic, and sedimentary.

Igneous are rocks born in fire, so to speak, through vulcanism or other tectonic activity. Metamorphic are rocks created by physical or chemical changes in the structure of other rocks, mainly through pressure and temperature. And sedimentary rocks come to us through the forces of deposition or other accumulation accompanied by cementation. Sedimentary rocks are usually characterized by layering or stratification formed by particles of varying degrees of size or fineness.

Nearly a billion years ago, there were highlands along the margins of what is now the continent of North America. Over time, silts, clays, pebbles, gravels, and other loose materials from those highlands washed into adjacent lowlands. The rock layers they formed are known collectively as the Ocoee Super Group, now between 545 and 450 million years old. With even more time, those materials cemented into layers some nine miles thick in places. Within this collection of strata, there is a smaller subgroup, the Snowbird Group, and more refinement of it yet will take you to an individual layer called Roaring Fork Sandstone, a greenish-gray, fine- to medium-grained metamorphosed rock which only rarely makes an appearance in the eroded layers seen in a streambed or along a roadside.

To bring our story forward, between 310 and 245 million years ago, the African tectonic plate collided with the North American plate. This uplifted the Ocoee Super Group from Newfoundland to Alabama, bending and folding its components and pushing them northwestward to eventually set the stage for the Smokies of today.

There is an outcropping of Roaring Fork Sandstone near the entrance to the Greenbrier Cove section of the Smokies. The Middle Prong of the Little Pigeon River cuts through this outcropping where it has formed beautiful potholes, dancing rapids, and small waterfalls. It is a premier location from which to photograph Smokies water. When I am there, the definition of “old” seems clearer to me, and my own time here more miniscule than ever.

 

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Don McGowan owns and operates EarthSong Photography. For five years he was the staff photographer for Friends of the Smokies. He offers workshops and photography instruction in beautiful locations around the country, including the Smokies.

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