My next post about the Geology of the National Parks Through Pictures is from our move across the country from Utah to New York. Along the way we visited 13 National Parks as well as some other sites. This was the 9th National Park along the way.
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.
-----------------------------------------------------------------------------
Obligatory entrance sign.
The Badlands are a very geological park, where the geology is the focal point of the beauty of the park. Even the term "badlands" is a geological term meaning a landscape made up of generally soft sedimentary rock that erodes easily and has a lot of streams eroding the landscape with little plant life to inhibit the erosion. The main road, Badlands Loop Road, that travels through the park, actually does not cover the vast majority of the park, which is much more difficult to get to. However, there are still a ton of geological sites that can be viewed from the main road. Below is a picture from the visitor's center of the overview of the geological stratigraphic column featuring the main park formations.
 |
| Geological sign from the Badlands NP Visitor's Center |
The oldest formation, at the base of the park, is the Pierre Shale. The Pierre Shale is Cretaceous in Age (~75 to 69 million years old) and formed when this area was covered in a vast inland sea known as the Western Interior Seaway. The Pierre Shale covers the lower levels of the landscape towards the northwest of the park, away from the main road. There are some places along the main road that you can see the Pierre Shale, such as at the Pinnacle Overlook, near the western entrance to the park. The shale is at the base of the erosion escarpment here. Within the Pierre Shale, several fossils can be found such as ammonites and mosasaurs. These lived at the same time as the dinosaurs, but since this area was covered in water during the Age of the Dinosaurs, dinosaurs were not to be found.
 |
| View from the Pinnacles Overlook |
The yellow layer immediately above the Pierre Shale is known as the Yellow Mounds. It is a weathered extension of the Pierre Shale, that was altered when the Western Interior Seaway went away. Within this layer, which can be plainly seen at the Yellow Mounds Overlook pictured below, a rainforest grew up within the Pierre Shale and converted the upper portions of the shale into a soil, or what is now known as a paleosol (an ancient soil).
 |
| View from Yellow Mounds Overlook |
Above the Pierre Shale is the Chadron Formation. The Chadron Formation is Eocene in age (~37 to 34.3 million years old) and was formed along an ancient river floodplain. The Chadron Formation is made up of light gray claystone beds and represent an environment similar to the Everglades today. Fossils found here are alligators, early horses, and the large brontothere (AKA titanothere) mammals. In the above image, the Chadron Formation starts just above the red layer and continue upwards until they hit the layer with multiple horizontal layers within it in the left background. That is our next youngest formation, the Brule Formation.
 |
| Conata Basin Overlook |
The Brule Formation is Oligocene in age, deposited 34 to 30 million years ago, and is an interbedded siltstone and sandstone deposit with a lot of clay creating a pale-pink deposit with lots of beds. This was formed when the environment started to dry out from the floodplains of the Chadron Formation and became a savannah with rivers periodically meandering across the environment. Fossils include those of oreodonts, animals related to modern bison and camels, early dogs, and nimravids, animals that looked like saber-toothed tigers but were only distantly related. In the picture above, the Brule Formation can be seen in the upper portion of the outcrop, essentially in line with the fencing on the left side of the photo, and stretching across the view. It is also the entirety of the rock formations in the picture below (the Wild River Valley Overlook) and creates the tops of most of the erosional escarpments seen along the Badlands Loop Roads.
 |
| Wild River Valley Overlook |
The youngest rock deposit within Badlands National Park (although there are many younger sediments across the park, this is the final layer within the Badlands escarpment) is the Sharps Formation. The Sharps Formation is an Oligocene Age (30 to 28 million years old) sandstone river channel deposit. This formation can be seen in a few places in the park and is present only at the very top of some of the erosional peaks. Below it can be seen along the Fossil Exhibit Trail as the upper half of that big monolith in the middle of the image. The line about halfway up is the Rockyford Ash layer, a deposit created from a distant volcanic eruption 30 million years ago. The Sharps Formation sits directly on top of the Rockyford Ash Layer.
 |
| Fossil Exhibit Trail outcrop view |
This entire region then began to erode away, producing the pinnacles and peaks that we see today. This erosion started around 500,000 years ago as the Cheyenne and White Rivers eroded their way through the landscape. Because all of these rocks are very, very soft, they are eroding at a rate that is much faster than many other landscapes, especially those further west. It is estimated that 1 inch of rock is eroding away every year and that the entire badlands will be gone in the next 500,000 years. This rate is 10,000 times faster than the granitic rocks forming the center of the Black Hills where
Mount Rushmore and the
Crazy Horse Memorial are located.
 |
| Geological column with the fossils displayed on the Fossil Exhibit Trail |
Towards the western end of the Badlands Loop Road is the Fossil Exhibit Trail. The Fossil Exhibit Trail is a wonderful, 0.2 mile "trail", along a boardwalk with bronze exhibits of fossils with displays explaining the animals to whence they belong. As the trailhead sign states, there are seven types of animals displayed along the trail. As the climate changed in the area, each of these animals had to either move, adapt, or extinct. Since it is a loop, the fossils are laid out chronologically. We are going to go backwards through time, starting with the most recent fossils along the trail, and ending with the oldest fossils. You can see a great layout of the stratigraphic section (geology rock layers) and their associated fossils in the image above that was at one of the trailheads for the Fossil Exhibit Trail.
 |
| Oreodont fossil (Leptauchenia) display along Fossil Exhibit Trail |
The Oreodont fossil above, Leptauchenia, was found within the Rockyford Ash layer, and Leptauchenia lived from around 32 to 28 million years ago. An oreodont is what is known as an artiodactyl, which is an even-toed hoofed mammal. These include bison, big horned sheep, and camels, of which the camel is the closest living animal to the Leptauchenia.
 |
| Dying to become a fossil exhibit |
Along with the fossils, there are also these great displays which shows additional information beside just the fossil. The display attached to the Oreodont fossil is called "Dying to Become a Fossil" and illustrates some of the processes that an animal takes in order to become fossilized.
 |
| Nimravid (Nimravus) fossil display along the Fossil Exhibit Trail |
The next fossil is the Nimravid (
Nimravus) fossil, which was found in the Brule Formation and lived around 32 to 30 million years ago. Nimravids are animals that resembled saber-toothed cats, of which these cats are only very distantly related. Nimravids fall under the family Nimravidae, as opposed to cats, which are Felidae, however they all fall under the order Carnivora, along with dogs and bears. Some of the differences between Nimravids and true cats is that the nimravid skulls are much shorter than cat skulls and they walked flat footed, as opposed to cats who walk on their toes.
 |
| Fight for Survival |
This display, which was paired with the Nimravid skull, displays another aspect of paleontology, taphonomy. This is where paleontologists look at the various aspects of the fossil and try to discern things like how the animal died. In this instance, there is evidence by the hole punctures in the skull of one nimravid, that it was attacked by another one.
 |
| Dog (Hesperocyon) fossil exhibit along the Fossil Exhibit Trail |
This dog fossil (Hesperocyon) is an early ancestor to modern day dogs and was also found in the Brule Formation. This dog lived around 37 to 28 million years ago.
 |
| It's a Dog's Life |
Associated with the
Hesperocyon display is the "It's a Dog's Life" display, showing the eventual evolution of the
Hesperocyon into modern day dogs as we know them.
 |
| An early horse, Mesohippus, display fossil on the Fossil Exhibit Trail |
Next up on the Fossil Exhibit Trail is the
Mesohippus, an early ancestor to modern day horses. Unlike modern day horses, who only have one toe,
Mesohippus had three toes.
Mesohippus lived from 37to 30 million years ago and this fossil was found within the Chadron Formation.
 |
| Off to the races |
Alongside the
Mesohippus display is "Off to the Races", a paleontological display discussing adaptation.
Mesohippus's adaptation was the reduction of digits in it's foot from 5 toes, seen in earlier ancestorial horses, to the three toes in
Mesohippus, that will eventually evolve into the one toe of modern-day horses.
 |
| Alligator fossil along the Fossil Exhibit Trail |
The next fossil is that of an alligator skull, which lived in the region from 34 to 37 million years ago. This fossil was found within the Chadron Formation.
 |
| See Yea Later, Alligator |
The associated sign with the Alligator skull discusses the size disparity between ancient alligators and their modern day descendants. As can be seen with the above skull, modern day alligators are much larger, over twice as long in fact, than this ancestor.
 |
| Titanothere (Megacerops) lower jaw fossil exhibit from the Fossil Exhibit Trail |
Titanotheres, also known as brontotheres, are very large hoofed mammals that evolved during the Eocene (~50 million years ago) and later went extinct in the Oligocene (~28 million years ago). They lived in Asia and North America and several well known species can be found across rocks of western North America. This Megacerops lower jaw fossil was found within the Chadron Formation, just above the Yellow Mounds layer. They lived in this area from 34 to 37 million years ago.
 |
| Titanic Discovery |
The associated sign with the titanothere fossil discusses the process of early field work, where paleontologists go out into the field and dig out the fossils, often with the aid of knowledgeable locals, who initially find the fossils eroding out of the landscape.
 |
| Ammonite (Placenticeras) fossil exhibit along the Fossil Exhibit Trail |
The final fossil on the Fossil Exhibit Trail (or the first, if you went in the opposite direction than I did), and the only fossil that isn't of a vertebrate, is the ammonite fossil Placenticeras. Ammonites are ancient relatives to octopi, squids, and nautiloids. This fossil, since it is the only marine fossil, was found in the only marine deposits, the Pierre Shale, located at the base of the rocks within the park. Ammonites lived within this area from 75 to 67 million years ago, before going extinct shortly thereafter 65.5 million years ago.
 |
| Under the Sea |
The associated sign with the ammonite fossil is "Under the Sea", that describes that throughout time the environmental conditions have changed. What is now the badlands, was once under water during the Cretaceous within the Western Interior Seaway.
 |
| A display of several fossils found within the Badlands National Park at the Ben Reifel Visitor Center. |
At the eastern end of the Badlands Loop Road is the Ben Reifel Visitor Center, and here there are several actual fossil exhibits, as opposed to the "fossils" on the Fossil Exhibit Trail which are clearly casts designed to weather the elements and visitors. The above display shows fossils from the Brule Formation. These include a Subhyracodon skull (top of picture), which was a hornless rhinoceros, a Leptomeryx, a small deer-like animal, (top right), and the Archaeotherium (large fossil on the bottom). The Archaeotherium was a "big pig", that although looked like a pig was only a distant relation to modern day pigs and was more closely related to hippos.
 |
A display of more fossils found within the Badlands National Park at the Ben Reifel Visitor Center.
|
The above shows another collection of fossils from within the park. These were found within several of the rock formations. This includes a titanothere femur and skull, an alligator skull, and a tortoise. There are also several more fossil exhibits within the visitor's center and it is a stop well worth taking your time in.
References
