Thursday, February 3, 2011

Russ Manning Cleared of Geologic Crimes!

After accusing author Russ Manning of being confused about the Skyuka Arch yesterday, I confirmed that I was a little confused myself. It wasn't the Manning book I read twenty years ago, it was Natural Bridges of Tennessee, a 1979 bulletin of the Tennessee Division of Geology by James Corgan and John Parks. I remembered I had found the book in question at UTC's library and thought I might take another look at it.

Then another thought hit me like a wall of limestone going sixty miles an hour: I didn't need to go to the library! I had photocopied the pages of the bulletin all those years ago and stashed them away in my trailbook files.

The bulletin contains a description with measurements and even a photo of the Skyuka Arch. Yes, it is the same one Brady and I revisted yesterday. And yes, the two state geologists, of all people, are evidently the source of the confusion about the type of rock and its original elevation. "The rock that forms the bridge is obviously sandstone," they write. They go on postulate that "apparently this arch acquired its distinctive shape elsewhere and tumbled into place as a large boulder that rolled down the mountain."

My apologies to Russ Manning! Russ, you may have committed some minor plagiarism (and who doesn't, these days?), but you're not to blame for turning Monteagle limestone into Pennsylvanian sandstone.

Ah, Geology! Ah, humanity!

Wednesday, February 2, 2011

The Skyuka Arch

Almost twenty years ago, I read about a small but mythical arch on the side of Lookout Mountain. Russ Manning, in his 1992 book The Historic Cumberland Plateau: An Explorer's Guide, described it as "unique, possibly the only such arch in the world." Following Mr. Manning's description, Terry Hamrick and I located the tiny arch and I took a photograph.

Now, decades later, I had forgotten exactly where the arch might be but I did remember this about it: aside from the location, almost everything else Russ Manning had said about the Skyuka Arch was wrong!

I wanted to take another look just be sure that Russ Manning, who I don't know personally but would normally consider a reliable source, wasn't completely off his rocker when it came to arches on Lookout Mountain. So today Brady and I parked the truck at the Skyuka trailhead at the Highway 318/Alford Hill intersection. Walking up the highway a short distance to a wooden barrier that read "no parking" (still exactly as described by Manning), we could see it from the road. The Skyuka Arch beckoned! As arches goes, this one was just an infant: about five feet tall, two feet tall, and two feet long. As Manning says, the arch is really nothing more than a short section of solution passage exposed to the elements.

Beyond that it gets weird. "The arch-shaped rock is sandstone," Manning writes, "while the surrounding rock is siltstone. The most likely explanation is that the arch originated atop the mountain, perhaps as the opening to a cave or spring, but then fell, coming to rest in its present location, forming an arch."

Whoops! I'm no geologist but I do know that the arch and most of the rocks in immediate area are all part of the same outcropping of limestone, not sandstone nor siltstone, and that particular bit of rock is completely at home at its current elevation. There are plenty of sandstone boulders in the area that came from the top of the mountain, but the Skyuka Arch is not among them.

That said, I salute Mr. Manning for bringing the world's attention to a small rock feature that otherwise would probably have gone unnoticed. The Skyuka Trailhead is actually quite a fascinating place, arch and all. The trailhead marks the point at which the Old Federal Road starts up the mountain. The area has huge boulders, massive sinkholes, English Ivy growing on a Kudzu scale, red barrels, mysterious holes, and even a secret hideout under a large rock that Brady and I discovered only this evening.

A secret hideout, you ask? Where? We could see it from the Arch, and that, my friend, is just another reason to visit that most infamous of the arches of Lookout Mountain.