2018/01/18

Two More Secrets of Putnam County

Verble Hollow
This cove in the area of Monterey is home to a spectacular 80 foot waterfall that emerges from a cave, and disappears into a cave. The caves are nerd-holes (caver jargon for a cave that only a geeky caver would want to visit), but the configuration of a waterfall isolated on a mountainside is pretty impressive. If you've seen Virgin Falls, or Lost Creek Falls, this should look familiar since it's the same geology that causes the others.

The land is managed by Belle Ridge Retreat. They have cabins, campsites for RVs and other vehicles, and trails for hiking and UTVs. You can connect with them on Facebook also.

Verble Hollow Falls 1, Putnam County, Tennessee
Verble Hollow Falls, Rami Ayoub, Putnam Co, TN

Bee Rock
An east facing cliff face just outside Monterey with an overlook, climbing routes, and a beautiful bed and breakfast called The Garden Inn at Bee Rock is just some of what you will find there. The inn and the overlook are on separate properties, but access may require cooperation of the inn. The main rule for accessing the Bee Rock overlook is to limit your visit to daylight hours. This should go without saying, leave no trace. Lots of people don't. Let's clean up after them and make the world a better, not worse place.

Kathie South Ferrari, Jason Lavender, Bee Rock, Putnam County, Tennessee 1 Bee Rock overlook, Putnam County, Tennessee 4

Flynn Lick Impact Site

Originally appeared in STANDING STONE PRESS, Monterey, Tenn., October, 1980
Reproduced with permission.


Dr. Richard C. Finch Associate Professor of Geology Tennessee Technological University

Imagine that you are a fish ... a long, long time ago. You are a marine fish, swimming in the shallow sea that covered most of Tennessee during the Early Devonian period. Although life has barely crept out onto the stark land surfaces, the  oceans teem with myriad life forms, and you are King: the largest, most  sophisticated animal alive, with no enemies big enough to worry you. You are content, for the world is yours.

Summertime and the livin’ is easy... Fish are jumpin’... Suddenly, as you are basking in the sun-warmed surface waters, a bright speck of light in a different portion oi the sky catches your eye. It is difficult to see at first, and you struggle to focus and see across the ocean – atmosphere interface, but faster than the sentence can be typed, and long before your fish brain can formulate a reaction, the speck has grown into a streaking, blazing ball of fire. Then, mere seconds later, your tranquil world is burst asunder by a mighty explosion. You have no time to turn and swim away; your body shudders and  our swim bladder feels as if it will rupture as you are jolted by powerful shock wave travelling faster than any sound you have ever known. In fact, the sound comes later, along with the waves that heel you about and sweep your helpless, stunned body along for what seems like an eternity.

But you are among  the lucky ... Millions of relatives are belly-up over an enormous hole in the sea floor, more than two miles across, and as much as 200 feet deep places. A ragged circle of low islands of tilted rock layers marks the crater rim, and another knob of shattered rock now stands in the center like a bulls-eye.

“What the heck happened?” you finally manage to ask yourself. Until the day you die you never forget that cataclysmic explosion. But you never know the answer. Today, some 360 million years, later, Jackson countians farm the valleys where the fish once swam, and geologists roam the hillsides seeking the answer to that ancient question: what happened geologic eons ago to cause the strange circular area of disturbed rocks now exposed by the downcutting of Flynn’s Creek and its tributaries.

More than a century ago, James Merrill Safford, A.M., PhD., and M.D. — Tennessee State Geologist from 1854 to 1850 and again from 1871 to 1960 — noted that the rock layers in the area upstream from Flynn’s Lick were tilted and broken by faults, quite atypical for strata in central Tennessee. Since then, the “Flynn Creek structure” has been examined by dozens of geologists, probed by the drills of hopeful mining companies, visited by geology classes from various states, and been the subject of a Phi) dissertation. The author of this study, Dr. Dave Roddy, is continuing his investigations today, as a geologist for the US. Geological Survey. Dave thinks he knows what happened here so long ago. Dave believes that the Flynn Creek structure is what geologists like to call an “astrobleme" —- the scar left on the earth by the awesome explosive impact of  large meteorite or comet.

Anyone who has driven the blacktop that winds through Flynn Creek valley knows that there is no “meteor crater” out there. What can the geologic eye see that the average motorist misses? The observant highway traveler can see tilted strata and brecciated (shattered) rock layers, but geologic mapping and sampling is necessary to bring out the overall pattern of the disturbed zone. Consider what Dave Roddy and other geologists have found: the disturbed area is circular, being about in diameter; the disturbance is most severe in the center of the structure, where a block of tilted rock layers have been uplifted about 1100 feet above its normal stratigraphic position; an extensive zone of intensely brecciated rock surrounds this central uplift; rock cores taken from drill holes show that the brecciated layers are underlain by folded and faulted strata, but that the disturbance in these beds dies out rapidly with depth, so that about 300 feet down the rock units are flat-lying; surrounding the breccia deposits is a “crater rim" of folded and faulted layers, the fault lines and fold axes being concentric about the crater; the Chattanooga Shale, a black shale normally about 35 feet thick in this region, is as much as 180 feet thick within the Flynn Creek structure; no volcanic rocks have been found associated with the structure; no meteorite fragments have been found in the structure, but peculiar cone-shaped structures known to geologists as “shattercones” can be found in some of the rocks of the central uplift.

The above geologic data, in conjunction with data from similar structures elsewhere on earth (and on the moon, Mars and Mercury), plus experimental data from laboratory high velocity impact cratering, strongly suggest that the Flynn Creek structure is the result of the explosive impact of an extra-terrestrial body crashing into the earth. An alternative hypothesis (formerly favored by most geologists) is the “cryptovolcanic" origin, which attributes the circular disturbed zone to a deep seated, “hidden” volcanic explosion within the earth. The fact that drill holes show that the deformation decreases at depth argues heavily against the theory. So does the presence of shattercones. These small cones of rock have been formed in laboratory experiments using shock waves generated by the impacts of high velocity projectiles. Volcanic explosions do not appear to generate the hypervelocity shock waves necessary to produce shattercones. The uplifted block in the center of the structure is a feature common to many impact craters on the moon, Mercury, and Mars. The lack of meteorite fragments can be explained by assuming the impacting body was a comet made of ice, or that the explosion was so intense that the meteorite was vaporized.

Whatever its origin, it is known that a large, deep circular hole existed in this area prior to the deposition of the Chattanooga Shale, for the shale accumulated to abnormal thicknesses in this hole on the sea floor. This fortuitous happenstance allows geologists to estimate the age of the structure: the Chattanooga Shale is considered to be of Late Devonian age. The crater had to have been formed shortly before the deposition of the shale, approximately 360 million years ago.

Much has been learned about the Flynn Creek structure, and much remains to be learned. Minerals companies are interested in the brecciated rock and faults which might be favorable places for deposition of sphalerite, fluorite or other economic minerals. The Defense Department is interested in the nature of explosion craters and the mechanics of their formation. Oil companies are always interested in uplifted structures. And geologists in general would like to answer the ancient fish’s question, just what the heck happened, anyway?

Birdwell Cave, Jackson County, Tennessee
Ric is pictured (center) inside Birdwell Cave which is inside the Flynn Creek impact structure.

A Day Tour of Jackson County

Cummins Falls, Cummins Falls State Park, Jackson County, Tennessee 2 When most folks hear about Jackson County, Tennessee, not much comes to mind. With the small city of Gainesboro, and the nearby Cumberland River, on the surface there seems to be little of interest there. Nothing is farther than the truth.

Many people don't realize that Cummins Falls is in Jackson County. While Cummins is an amazing waterfall, this blog post is about the less well known locations. Not all of these are on public lands, and I do not encourage trespassing. Please be respectful of landowners.


Flynn Creek Impact Structure
That's right, there's a meter impact site in Jackson County. Maybe two. It doesn't look like the classic
Barringer Crater impact though, and for good reason. The feature is quite old (around 360 million years before present), and it ended up getting buried under a lot of sediment, which was both good and bad for us. Good, because it preserved the structure, bad because it takes a trained eye to figure out what's going on.

Much of the property associated with the impact site is private. That said, there are excellent rock outcrops visible on the side of the road which tell the story of the impact.

For more information on the impact site, check out this great field guide. Also, this article written by my friend Dr. Ric Finch, and published here on my blog.

The caves pictured below are all within the impact site and allow one a more clear picture of the rocks involved in the impact.

Birdwell Cave, Jackson County, Tennessee Hawkins Impact Cave, Clinton Elmore, Jackson County, Tennessee 1
Wave Cave, Jackson County, Tennessee 1

The Boils
The locals call it The Boils, but not because the water is hot (it's a chilly 55º F), but because the water appears to boil as it wells up under pressure. The Boils is a roadside curiosity, and for a very long time no one knew for sure the origin of its waters. However, in the summer of 2015, a team of scientists (including myself) did a large scale geographic inventory of the region, and discovered several sinkholes taking in large amounts of water on Spring Creek which were shown to feed The Boils.

The Boils is managed by TWRA as a river access point and is open to public visitation year round. Which is convenient as it's also a nice place to photograph the sunset on Roaring River.

The Boils are interesting enough to warrant their own blog post. If you want to learn more about them, go here: http://chuck-sutherland.blogspot.com/2017/01/the-boils.html

The Boils, The Boils WMA, Jackson Co, TN


Wash Morgan Hollow
Wash Morgan Hollow (or "holler" if you're a local) is a wildflower preserve managed by The Nature Conservancy of Tennessee. With no real trail, one can walk up the valley to its head and find Wash Morgan Falls. Dozens of species of flowers can be found there throughout the year, and it is also a great destination for birders.
For more information look at TNCs webpage, or TDECs webpage.
Saxifraga virginiensis, Wash Morgan Hollow, Jackson County, Tennessee

Spring Creek Scenic Rivers
A scenic river isn't public land, but it is a special designation of river which prevents it from being impounded and is also used to recognize their scenic beauty. That there are three of these within the relatively obscure county of Jackson is noteworthy (the other two are Roaring River, and Blackburn Fork River).

The river originates from a blue hole karst spring in Putnam County, winds its way down to Waterloo and makes several small and beautiful waterfalls (and is joined by a spectacular waterfall at Mill Creek), and enters into Jackson County. It has rapids to kayak, pools to swim, and fish to be caught. For a long stretch a gravel country road follows its course and makes an enjoyable scenic drive any time of the year.

For more information on this and other scenic rivers in Tennessee, go here: http://www.paddletsra.org/scenicrivers/designated
Confluence of Roaring River and Spring Creek, Jackson County, Tennessee

Dirt Cave
Dirt Cave is more entrance than cave. None live that still know if and how the road changed the hydrology of the area. We suspect that this may have once been a large outflowing spring and the road was put in place blocking it up. Unfortunately we know from the trash that morons love to dump in there that the water flows underground, but no traces have shows where the water comes up. Local lore says that it returns to the surface at the nearby Boils, which seems likely.

The cave has been horribly abused. I am able to look at this for what it is, a cathedral of karst, a place of reverence. I hope one day we can clean the graffiti from its walls and end the illegal dumping there forever. But we are a long way from that time still. If you visit, please respect this place.
Dirt Cave entrance, Jackson Co, TN

Roaring River Park
Just above the confluence of Roaring River and the Cumberland River, on the south banks of Roaring River is a city park. There one will find walking trails, a boat launch, a pier to fish from, a pavilion, and playground equipment. Whether you're looking for a good place to scout waterfowl and other wildlife, put a kayak into the river, or have a picnic, this is a nicely developed area adjacent to a beautiful river.
Sunset over the Cumberland River, Gainesboro, TN

The Bull and Thistle
Few restaurants stand out as so excellent as to warrant me deviating from directing people to natural places. The Bull and Thistle is one of those places. My advice is that you visit as many beautiful natural places in Jackson County as you can and finish your day with a hearty meal. You'll thank me for the recommendation.