Geology and Topography of Tennessee
has lots of angular white quartz pebbles. The difference between breccia and conglomerate is the shape of the "clasts", or larger rocks. Conglomerate has rounded pebbles, breccia has sharper, angular gravels. This type of sedimentary rock is common in the Appalachians. I found this one along the Ocoee River in southeast Tennessee.
Many of the huge boulders at Laurel - Snow Pocket Wilderness have cracks from water erosion. Over time, the boulder will become sand once again.
, the largest in the eastern United States. One trail takes hikers over the top of one of the arches. This is not a good place to take children, there are no safety fences or rails on the arch.
Much of the Cumberland Plateau is composed of sandstone. The stone breaks into flat sheets. The sandstone is commonly used as a beautiful building material in buildings on the plateau.
I thought this rock was interesting, the smaller stone is wearing down the shale when it gets tumbled by moving water. This was photographed beneath the bridge at Bald River Falls.
This cliff at the Big South Fork is made of sandstone, note the pockmarked erosion of the stone.
Cades Cove is a beautiful low area in the Smokies. Until the government took over the land for the park in the 1930's, this area was a thriving community. The cove, called a "geologic window", has eroded through the Great Smoky thrust fault to expose even more ancient rock.
This odd sandstone was also found at the base of Maudes Crack. Often the sandstone has veins of harder iron oxide "cement", the softer sandstone erodes around the veins leaving the protruding lines. Iron oxide is also called "rust".
means "moss animal". The tiny tubes visible in this photo contained an individual animal. This is a very common fossil in east Tennessee since this area was covered by a shallow sea 400 million years ago.
A Gastropod fossil found in a limestone rock at Haw Ridge in Oak Ridge.
, was a source of copper, and small amounts of silver and gold. The mine opened in the early 1850's and closed in 1987. The area is infamous for the incredible ecological damage it suffered due to soil, air and water pollution. At one time, 50 square miles of the area was completely bare of vegetation because of sulfuric acid fumes released during smelting of the ore and toxic water runoff from the mine tailings. Without plants, the soil became eroded, causing severe siltation in the creeks and rivers. Much of the aquatic life in the Ocoee River was killed off because of the siltation and high concentrations of heavy metals in the water. In the late 1930's scientists began attempting to reclaim the "biological desert" surrounding the mine. All of the pine trees in this photo are part of the reclaimation project. A small area around the mine has been left as it was "for old time's sake". Ducktown is located in the far southeast corner of Tennessee at the intersection of Hwy. 64 and Hwy. 68. There is a small museum at the site that shows life in the area during the time the mine was up and running.
along I-40 above Rockwood from the car as we zipped along at 65 mph. It is easy to see the different layers of sandstone and coal in the rockwall.
was photographed along the bank of the Ocoee River. The runoff from the mine tailings continues to make the water in the river more acidic than normal. Adding alkaline (higher pH) rock helps neutralize the acidic (lower ph) river water.
Much of the sandstone on the Cumberland Plateau is layered in thin slabs. I wouldn't want to be standing under the cliff when these pieces break off!
Blue Quartz conglomerate boulder in the Smokies
This lovely sandstone slab was part of a bench along a trail at the Ocoee Outdoor Center. The pink, brown, and orange colors come from minerals mixed with the sand, such as iron oxide (a.k.a. "rust"). These are called Liesegang bands.
is noticable as soon as you walk into the cave. Saltpeter smells much like gunpowder; it should, it is one of the ingredients of the explosive powder. It was mined from this cliff during the Civil War. This makes a nice resting place for hikers on their way to Mt. Leconte.
Sandstone rock houses are common along the cliffs on the Cumberland Plateau. Some, like this one, are quite large and offer a safe retreat from the frequent summer thunderstorms.
The view of Hwy. 441 from the Chimneys.
Note the layers of rock in this Stromatolite.
Another Bryozoan fossil
On a walk along the trails at Haw Ridge youll see lots of limestone outcroppings that contain fossils of ancient sea animals. Look closely at this photo, youll see some nice brachiopod fossils. Limestone is an indicator that an area was once under an ocean. Limestone was formed from seashells that settled to the ocean floor. Over long periods of time and pressure the calcium carbonate (CaCO3) in the seashells was transformed into limestone. Geologists test limestone by putting drops of hydrochloric acid on it; if it bubbles, the rock is limestone. The hydrochloric acid reacts with the calcium carbonate and releases carbon dioxide gas (CO2).
Charlie's Bunion; Anakeesta shale
. It is amazing to realize that this rock was a muddy ocean bottom hundreds of millions of years ago, now it is over 5,000 feet above sea level!
I found this broken piece of Conglomerate rock along the trail at Colditz Cove State Natural Area. Note the quartz pebbles embedded in the rock. There are holes where some of the pebbles have been dislodged.
, 30 miles east of Nashville. The soil in the cedar glades is very thin and in some places, non-existent. A great book to help learn about the geology of Tennessee is: A Geologic Trip across Tennessee by Interstate 40 by Harry L. Moore. If you are interested in getting deeper into the chemistry of the rocks, check out this website:link
This is a layer of rock (probably shale) that can be seen on the trail to the bottom of the falls.
A close-up of the Shale outcropping. Note the different shades of gray, these were probably made up of sediments from different flooding events hundreds of millions of years ago. This type of rock is extremely unstable, it would crumble away if someone tried to climb it.
. Granite rock is made up of quartz, horneblende, feldspar, and sometimes biotite mica minerals. If you find 2 small white quartz stones in a creek, strike them together in the dark and you'll see a small glow of light called a piezo electric charge.
are one of the most popular sights in the park. A hike of less than a mile brings you to the North and South Arches. The North Arch spans 93 feet across and is 51 feet high. The South Arch is 135 feet across and 70 feet to the top opening. The base of the arches is deep sand, like a giants sandbox.
Not all of Cedars of Lebanon has flat sheets of limestone, this area of the park is honeycombed with caves and dotted with large limestone boulders.
It is very difficult to photograph the Arches because they are so large.
. As the sticky algae grew, they trapped sand and other sediment and other layers would grow. The organisms grew quite large over hundreds of years. Over time they became fossilized. Since cyanobacteria are able to photosynthesize, scientists believe that these primative algae may have been responsible for putting the first oxygen into the Earth's atmosphere. Many of these fossils are over 3 billion years old!
Since limestone is made of the remains of ancient sea creatures, it is not unusual to find fossils like this cephalopod and spiral gastropod. This type of limestone is considered fossiliferous. It is hard to believe that the part of the country that is now Tennessee could have ever been underwater, but the rocks and fossils help tell a fascinating story of our ancient past. Limestone rocks at Cedars of Lebanon date back to the Ordovician period, 500 million years ago.
During the drought of 2007 we went to Piney Falls to see them with no water. I found these Horsetail Fossils in the rocks at the base of the falls. Normally there is too much water and spray to be able to take pictures there. These ancient plants were the distant relatives of today's Horsetails (Equisetum), also known as scouring rushes. They grew in this area long before the dinosaurs lived.
A large Slate outcropping on the Chimney Tops crest.
Rocks in the streams in the Smokies show a tremendous diversity of color and patterns. These smooth stones are made up of shale, slate, quartz, and Thunderhead Sandstone.
Cedar glades have many unique wildflowers, such as this Fameflower. It is amazing how these delicate little flowers can live in such harsh conditions.
This Slate makes up the top of the Chimney Tops in the Smokies.
is metamorphosed shale, it is harder and more dense than shale. It is easy to see the thin layers in the stone. Metamorphic rock often forms layers due to being squeezed under pressure. Since it separates into thin sheets, slate has been used for chalkboards, roof shingles, and pool table tops.
made of solidified, fine-grained mud. When exposed to massive pressure and heat far below the earth's surface, shale metamorphoses into slate. To remember which rock turns into which, I think of H coming before L in the alphabet and the "H" in shale coming before the "L" in slate, therefore shale came before slate. Shale will break into flat, angular pieces when broken (fissile), a second type of siltstone called, "claystone" is not fissile.
is worth the effort, the views are fantastic! The soil at the top of the cliff is very sandy from erosion of the sandstone. Who knows, maybe someday the sand will become sandstone again far off in the future!
Limestone is slowly dissolved by the weak acids in rainwater, resulting in caves. Much of Tennessee is "hollow", riddled with numerous caverns of all sizes. Limestone landscape, called "karst" can also have sinkholes and depressions. One of the tests that geologists run on limestone is to put a drop or two of hydrochloric acid (HCl) on the rock, if it bubbles releasing carbon dioxide (CO2) from the calcium carbonate (CaCO3), the rock is limestone.
- these are the larger, easily visible pieces, such as the larger grains of sand and the pebbles 2. Matrix - this is the smaller sediment around the pebbles 3. Cement - this is the substance that holds the matrix and clasts together, a type of mineral "glue", it can be silica, iron oxide, or calcite. Conglomerate rocks has clasts of rounded pebbles, breccia has clasts of broken, angular rocks.
were found in a limestone rock at Haw Ridge in Oak Ridge.
an Oscar See Down My Pants Pocket? Tom Jones Can. That's Quirky!" (Well, he didn't say "quirky", but the other "q" word is not politically correct!) This is a convenient way to remember: Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Tertiary, Quaternary. The dinosaurs lived during the Triassic, Jurassic, and Cretaceous periods 230 to 65 million years ago. See this link for a good explanation of geologic time.
is a hard type of sedimentary rock that is very common in Oak Ridge. It is made of microcrystalline silicon dioxide (SiO2). See Geology.com for more information.
is the highest point in Tennessee at 6311 feet elevation. On a clear day, you can see for many miles from the observation tower.
, at Big South Fork, is an easy way to get down from the top of the cliff. It looks difficult from the bottom, but it beats having to rappel over the side using a rope. This gives you an idea of how thick some of the sandstone layers can be on the Cumberland Plateau. It is still a long way to No Business Creek at the bottom of the gorge. (see the Big South Fork gallery for more photos)