Did you see this in the news? NASA is starting a new Mars mission, and this one has a very exciting goal: to find evidence of past life! And to study the habitability of Mars for past life and for humans in the future.
A new rover, called Mars 2020 until a name is selected (update: Mars Perseverance Rover), will be sent to Mars this summer, with an arrival on Mars February 18, 2021. The rover will explore the Jezero crater for about one Martian year, equal to 687 Earth days. Jezero crater was chosen for study because there is evidence that this crater once contained a lake.
Two rivers, on the left side of the picture, flowed into a crater. A flood like broke through the crater wall and allowed water to drain out of the crater (upper right). Inside of the crater is a former delta formed as sediments were deposited as the rivers entered the lakes and deposited sediment.
Spectral analyses of the deltas and fans have revealed the presence of carbonates and hydrated silicas.
Carbonate is a chemical composed of carbon, oxygen, and a metal or hydrogen. For example, chalk, seashells, and egg shells are all made of calcium carbonate crystals (CaCO3). Carbonates need liquid water and an atmosphere with carbon dioxide to form. On Earth, carbonate rocks may be formed by the accumulation of tiny fossil shells, but carbonates can form abiotically (without life). Limestone, a carbonate rock, is a good preserver of body fossils and trace fossils. Silica, a combination of silicon and oxygen, forms in water. Chert and flint are examples of silica rocks. Chert is also formed by the accumulation of tiny shells, but these are made from silica, not carbonate.
Any fossils that are left on Mars from its warmer, wetter periods would likely be found in carbonate and silica deposits. Scientists expect that these fossils would be microorganisms (single celled organisms).
In addition to searching for fossils, Mars 2020, Perseverance will also:
Determine past climates that may have allowed ancient life to exist
Study the geology of Mars, including the processes that affected and altered Mars’s surface, as well as looking for rocks that formed in water and what they might reveal about past life
Help prepare for human explorers by studying radiation levels on Mars’s surface and chemicals common in martian soil that are known to be harmful to humans.
This may be a very exciting mission, but the wait will be long! The search for fossils will be the last part of the mission. But we’ll keep you posted!
On June 3rd and June 4th of 2019 I traveled to Tupelo, Mississippi with another fellow fossil collector to collect Cretaceous marine fossils. This was the first time I have collected fossils dating back to the Mesozoic Era. The first location we visited was part of the Ripley Formation in Blue Springs, Mississippi. The Ripley Formation was deposited a few million years before the extinction of the non-avian dinosaurs about 71 million years ago. During this time, Mississippi was submerged under a shallow sea, and North America was cut by a large inland seaway known as the Western Interior Seaway. Mississippi’s Cretaceous oceans were teeming with life. The most common fossils found were oysters and clams that were plentiful in those ancient seas.
The largest oyster found in the Ripley Formation was Exogyra costata. Other fossils found in that rock unit were marine snails called Turritella vertebroides, which were the most well preserved fossils from the Ripley Formation. Another common fossil unearthed as we dug under the Ripley Formation and approached the Coon Creek Formation were crab carapaces. One species of crab that I found reach to about 5 inches in length. I was nearly in shock as I was excavating it from its silty tomb. After we spent a few hours collecting, we began to wrap up our fragile finds in tin foil and put them in crates for safe transportation back home. Our last site we visited was an open field with exposures of the Demopolis Chalk Formation. This rock unit is a few million years older than the Ripley Formation. Nevertheless, this rock unit is rich in marine fossils.
It was in the beginning of summer and it was about 90 degrees, but what we were out looking for were shark teeth. In order to search for them we had to get on our hands and knees and crawl on the white hot ground. As uncomfortable as it may seem, this is how some of the best fossils are found. When collecting fossils the best thing you need to have is patience. After about 4 minutes of searching I saw something brown and shiny glinting in the sun. It was my very first Late Cretaceous shark tooth! The tooth belonged to the genus Squalicorax. This was about a 7 foot shark that swam the seas of Mississippi about 75 million years ago. It wasn’t long before I came across my second shark tooth, but it wasn’t as complete. Besides fossils we both found beautiful iridescent crystals of the sulfide mineral marcasite. After we spent an hour searching for shark teeth and other marine fossils in the Demopolis Chalk we decided to call it a day and head back to Huntsville, Alabama to start the next day of adventures.
It’s no secret that one of my favorite hobbies and past-time outside of researching fossils is fossil collecting for fun. So when I went home over Thanksgiving 2019, of course I took it as an opportunity to visit one of my favorite fossil localities, Calvert Cliffs in Maryland, on the Chesapeake Bay. I dragged my mom and two siblings with me on this overnight adventure, and it was a blast!
These cliffs are exposed along the east coast of the US, and are a part of Westmoreland State Park which I’ve written about previously. They contain beautiful fossil of late Neogene age (Miocene to Pleistocene, about 23-0.01 million years ago). The cliffs in Maryland contain the same age fossils, and the rocks and sediments are part of the Chesapeake Group (the name given to the group of layers that the fossils are contained in). There are several beaches in the area that member of the public can hunt at, but I’ll just go over a few sites we visited.
The first place we visited was Calvert Cliffs State Park. The park has a moderate entrance fee ($5 in state, $7 out of state), but it’s totally worth it. There are bathrooms here, along with a playground for kids (although, we all had a blast on the merry-go-round, to the point of almost puking). It’s a great place for families to visit with nice facilities. The trail to the beach is about 1.8 miles down a gentle slope, and towards the end of the trail there is a low-lying land where we saw several species of ducks and aquatic plants. At the mouth of the trail, there is a wooden bin with a variety of sifters for visitors to use to find fossils. The beach is flanked by the cliffs on either side, which are roped off. The cliffs are an excellent place to collect, however, they are and can quickly become wildly unstable, with huge blocks falling with enough velocity to seriously injure someone standing below. We found a few small shark’s teeth here, and some gastropod (snail) molds in the rocks. Nothing phenomenal.
The next place we visited was called Brownies Beach. Here, the beach is much longer, and at low tide, you can probably walk the beach for quite a while. Be warned, though, because like Calvert Cliffs, this stretch of beach is also prone to falling blocks. We spent quite a while here, and again, all we found were a few small shark teeth (scroll down for a video of my brother finding an incomplete tooth). There wasn’t a fee during the winter, but it did seem the beach has a fee during the summer.
The next day, I took everyone to Matoaka Beach Cabins. This was a really cool spot! The beach is privately owned, with the owners charging folks a mere $5 to access the beach all day. In addition, you can rent cabins here steps from the beach! The beaches are long and are not underneath the cliffs. We had a blast here, but at this point, we were in the midst of a huge rain storm that was hitting the east coast. We were drenched within the hour, and had to give up hunting for the rest of the day. We found another few shark teeth, some smaller pectens (clam) shells, and a dead pelican that I refused to let my siblings take back to my car. This beach is somewhere I’d love to revisit, especially at low tide. The shell line was wide, with several larger shells visible in the waves (the heavier teeth and fossils tend to be found with the same weight rocks, so finding larger rocks indicates the potential of finding larger fossils).
After leaving Matoaka, we then visited the Calvert Marine Museum. Being a paleontologist, I’ve visited a lot of museums, but this little museum remains one of my top five favorites. It combines the history of the region with paleontology and biology. For that reason, I’d recommend visiting the museum first. They have amazing display cases of the fossils found along the cliffs, so you can have an idea of what you’re looking for. You will also gain an appreciation of the rich wildlife in the Chesapeake Bay, and the native peoples that used to live here. Bonus, the museum also has three otters that are incredibly entertaining, as well as tanks of live horseshoe crabs, turtles, crabs, and fish species that are common in the bay.
For a list of fossils you can find in this region, information on the rock layers, and a list of all the beaches and their admission prices, check out the Fossil Guy’s website.
If you are on Facebook, I recommend joining the Fossils of Calvert Cliffs Maryland group. They share collecting advice, recommendations for beaches, and favorite restaurants. I consulted with the group before planning my trip, and several members gave me great food and beach recommendations!
I recently visited Big Bone Lick State Historic Site (Union, Kentucky) on the way back to Ohio from a weekend in Kentucky. I’ve been meaning to visit this place for years, so I’m glad I finally had a chance to do so! Big Bone Lick is an important site for paleontology, archaeology, and US history.
Big Bone Lick SP is the site of a salt lick, or area where animals come to obtain salt and other minerals by licking the soil for salt crystals. Natural salt and sulfur springs are the source of the minerals at Big Bone Lick, and they attracted animals from all over.
In historical times, white-tailed deer and North American bison visited the lick, but much larger mammals came during the Pleistocene epoch (2.5 million to 12,000 years ago), also called the “Ice Age.” The remains of extinct mastodons, mammoths, North American horses, ground sloths, and tapirs have been found here, as well as the still living bison, musk oxen, and peccaries. Some of them became stuck in mud and died, and their preserved skeletons became the source of the “big bones!”
Paleoindians hunted the megafauna at Big Bone Lick, and left behind their tools at the site. Native Americans continued to hunt here into colonial times, and told the Europeans about the big bones found in the soil. President Jefferson ordered Merriweather Lewis and William Clark to stop here on their expedition to investigate these reports. Specimens were excavated and eventually sent to France for analysis by Georges Cuvier, an anatomist credited with developing the concept of extinction. He compared the remains of Asian Elephants, African elephants, and the “elephants” found at Big Bone Lick and determined that these remains came a type of elephant that no longer lived. He named this animal Mastodon, but these fossils had already been described under the name Mammut. The study of these remains has given this site credit for the birth place of vertebrate paleontology in the United States.
Long after the bison were extirpated (no longer present in their native habitat, but not extinct) from Kentucky, Kentuckians mined salt and opened a health resort, at which people bathed in the mineral-rich water.
I have always loved the Pleistocene megafauna, and I make a point to see these fossils whenever I can. Mastodons are tied with Moropus(a distant relative of horses and rhinos, imagine a draft horse with claws!) as my favorite fossil animal, and get so excited seeing them!
The visitor’s center has nice displays about the megafauna found at Big Bone Lick, including fossil material and reconstructions of what they may have looked like. There is information about the Paleoindians that inhabited this region and their tools. Historical information about Lewis and Clark is also included in the displays.
Behind the visitor’s center are life-size statues that represent iconic Pleistocene megafauna. Many of them are“trapped” in the sediment, and are on their way to become fossils. This was the perfect opportunity for a selfie with a mastodon!
The site is actually quite large, and features a campground and several hiking trails. I took one of these trails to see the salt/sulfur springs. I could smell the sulfur as soon as I reached this point in the trail. It was pretty awful, and it amazes me that people came to bathe in these waters for the “medicinal properties” centuries ago.
I continued along a trail which follows Big Bone Creek. Fossils and artifacts are still exposed as the sediment washes away, and modern excavations occur when fossils are found on site.
Informational signs are included along the trails about the history of the site and about the animals that once lived in this region.
The park maintains a small herd of American bison (Bison bison) on its grounds. The animals are rotated around their paddock to allow the plants time to recover from grazing and trampling. Unfortunately for me, they were located too far away for me to see with them with my limited time. It is hoped that the ecosystem will be restored to its condition before the bison were extirpated from this area.
I had a great visit to Big Bone Lick State Historic Site! If you enjoy ice age megafauna, and are in or near Kentucky, consider stopping by! For more information, visit Big Bone Lick State Historical Site
Recently, I went to the Washington D.C. area to visit the Smithsonian Museum of Natural History (which you can read about here) and to attend a workshop on best practices for new faculty members. But while I was there, I spied some excellent geology right in the city! I already showed you some of those while I was in the museum itself, so I’ll show you some of the other amazing pieces of Earth history that I saw!
I want to remind you that looking at amazing geology doesn’t have to wait for you to be on vacation or in a faraway destination-you can see these sites anywhere, if you’re paying attention! If you want to read more of these types of posts, check out my post from last year on the geology of bathrooms.
This first image is of a beautiful stylolite in a marble countertop in the bathroom of a café in the center of Washington D.C. A stylolite is caused when rock, most commonly carbonate rocks like limestone (which we call marble when they are metamorphosed), are put under extreme pressure and the individual grains will compress and leak fluid, leaving behind a squiggly line, like what you see in image 1. Just beautiful!
Our next stop brings us to Union Station in Washington D.C., where I found this magnificent staircase completely by accident (image 2). I was visiting Gallaudet University and the first signing Starbucks, when I got turned around and ended up at a different Metro station than I had originally intended. Well, serendipitously, I found this absolute beauty, making the detour more than worth it. This rock, just like the image before, is a type of marble, though it has very different colors. The red color in this marble can be attributed to chemical impurities- red is typically what we’d see if iron and feldspar was present in the marble sample. You can also see veins filled with calcite and look like quartz all throughout the staircase! I was intrigued about where this marble came from, so I did a little research. There wasn’t a lot of information, but it seems that this marble likely came from Vermont (See this blog here: https://blogs.agu.org/magmacumlaude/2014/06/13/building-dc-union-station-just-the-floors/), which was created over 400 million years ago, when limestone produced from a shallow sea collided with a volcanic arc and metamorphosed in an orogeny, or a tectonic collision. This is a fairly common scenario with how we get a lot of our marble from the Paleozoic in North America.
Our tour continues to just outside of Washington D.C., to Arlington, VA, where I was visiting a friend in the area. As we were walking to breakfast, I was treated to a spectacular number of rocks featured in the buildings’ walls along the way. First, is a beautiful granite (image 3). The pink mineral is potassium feldspar (K-spar, for short), intermixed with the milky white mineral (quartz) and a lot of amphibole, the black colored mineral that’s heavily present on the left side of the block. Granite also usually contains biotite, a black mica. If you take a look at this granite, you’ll see that the individual crystals are quite large, which tells us a lot about its formation. It’s telling us that it was formed intrusively; meaning, it was formed in an area not exposed to Earth’s surface and it cooled slowly, giving the crystals time to grow. I stopped to take a photo of this because the amphibole (there are many varieties of amphibole-hornblende is the most common in granite) because the heavy presence of the swirling amphibole isn’t something I usually see in most granite samples. Second, I saw these gorgeous phyllite samples on the outer wall of a building (image 4). Phyllite is a low-grade metamorphic rock, which means it’s not exposed to extremely high amounts of heat and pressure, but it has undergone significant changes from its protolith (otherwise known as its parent rock). In the case of phyllite, its protolith was a shale (compacted mud). You can recognize phyllite by a few different characteristics. During the metamorphic process, muscovite (a soft mineral in the mica family) develops, giving phyllite a really lovely shiny appearance (you can think of mica as being like nature’s glitter; just like glitter, mica is nearly impossible to completely get rid of if you accidentally get it everywhere!). You can also recognize phyllite by the gentle bands that form. Many metamorphic rocks are foliated, which we can think of as banding across a rock. The more pronounced the banding usually indicates a higher amount of metamorphism applied to the rock. Phyllite has subtle banding, which indicates that lower amount of metamorphism.
So, this next image (image 5) isn’t in D.C., but it was found during this trip in College Park, Maryland on the University of Maryland’s campus. It’s another gorgeous example of granite, this time in a fountain. Sometimes it can be really hard to recognize rocks when you’re used to seeing them beautifully polished and sealed (like the granite in image 3, but you can definitely do it with practice!) Just like in image 3, if you look closely at this fountain, you’ll see large crystals, because it’s an intrusive rock, and the same types of minerals- our pink K-spar, milky quartz, and black amphiboles. An intrusive magmatic event from millions of years ago had to form and cool, and then that granite had to be exhumed (brought to the surface) for someone to make that fountain. So cool!
Last, but certainly not least, let’s look at the marble here in the Ronald Reagan airport (image 6). This gorgeous marble makes up part of a seafood restaurant right near the entrance to the airport, before you go through the security line. Sorry that the image is kind of far away, but this was the closest I was able to get before having to get through the security line! One of my favorite things about marble is how different it can look from sample to sample. This marble shows completely different features than the ones I showed in images 1 and 2-remember, the color of marble is driven by chemical impurities. You can see large scale veins of what is likely calcite all over the rock itself as well as some dissolution features on the left side.
I recently went on a fossil collecting trip associated with a FOSSIL Project workshop on digitization and imaging of fossils. To preface this, whenever you are looking to go fossil collecting you should make sure to be aware of the laws and rules in place in your town. The spot we were heading to abuts private land so one of the coordinators made sure to reach out to them ahead of time to request permission and explain what we were doing. To give back to the community, we also cleaned up the creek while we were looking for fossils. There is always trash or debris and this is an easy way to give back to the community you are hunting in!
In Florida, you have to prepare to be out in the heat. Surprisingly the creek was pleasant and we were pretty shaded for most of the day. I wore a UV protectant shirt, shorts, sandals, and a hat. Insects can really get you, so it’s also best to know what to prepare for and use lotion or bug spray to prevent any spread of disease.
I was mostly observing and helping facilitate this trip but I was excited to see others getting really into the fossil collection. This location is in the Coosawhatchie Formation which is Miocene (~23-5.3 million years ago) in age. It overlies the Eocene (~56-33.9 million years old) Ocala Limestone. The Ocala Limestone fossils are very different from the Coosawhatchie so they are pretty easy to distinguish from one another. Most folks were finding shark teeth, ray plates, clams, snails from the Coosawhatchie Formation and things like small echinoids and large benthic foraminifera from the Ocala Limestone. Specimens from the Ocala Limestone were often a white-cream color whereas specimens from the Coosawhatchie were very dark.
We also spent some time observing the local insects and sharing education apps for identifying fossils and modern life! Workshop participants were from all over the country so there was some regular chit chat and getting to know one another. I had known several participants for some time from various online platforms so it was really great getting to meet them in person! If you want to check out what the group was up to here is the myFOSSIL group that everyone was posting in: Imaging and Digitization for Avocational Paleontologists Workshop
I was also helping my friend and collaborator, Rich, with a study. He was interested in thinking about participant dynamics at workshops and field trips. So we had a matrix and were recording interactions between participants at the workshop and facilitators (/people running the workshop). He then also gave everyone a survey to see how people’s perception of who they interacted with matched what we observed. They were pretty close but perceived interactions were higher, which could be due to a variety of things. It has been really fun getting into some of these observational studies!
The Ilulissat Art Museum is a charming red house with robin’s egg blue trim nestled up against a grassy hillside in the town of Ilulissat, Greenland. Almost 5,000 people live in this seaside town, including the art museum’s cheerful and friendly curator. His face lights up at the prospect of new visitors, and he enthusiastically greets us as we enter. This kindly curator shows us around the museum, offering us a wealth of knowledge about the paintings and the artists. He tells us that the lower level is primarily for paintings by Emanuel A. Petersen, a Danish painter who spent time in Greenland in the early 20th century. His paintings depict tranquil yet breathtaking scenes of the landscape surrounding Ilulissat and other Greenlandic villages. Many show icebergs stoically floating in the fjord, and tall, snowy mountains colored pink from the alpenglow. Some paintings have boats and kayaks out at sea, while others depict sleds led by teams of thick-coated dogs. While each scene may be different, each of Petersen’s paintings is so uniquely Greenland.
It’s no wonder Petersen produced enough paintings to fill an entire floor (not to mention the 150+ pieces of his artwork at the museum in Greenland’s capital, Nuuk). The landscape around Ilulissat is an alluring contrast of rounded green hills and blue-white icebergs. No more than 20 kilometers inland, the Greenland Ice Sheet spills out into channelized outlet glaciers like Jakobshavn Isbrae–the fast-flowing ice stream that produces the icebergs occupying Ilulissat’s fjord. Up and down the coast of Greenland, glaciers flow from the ice sheet and fill the valleys and fjords with ice.
Many local Greenlanders travel over this ice, including our friendly museum curator. He has a team of six sled dogs–which we’re told is a relatively small team–that pulls his sled across snow and ice. For years, he and his wife have been traveling with their sled dogs to a spot along the margin of the ice sheet. There, an outlet glacier flows into a water-filled valley with rocky hills forming the sides. Just a few years ago, the curator and his wife arrived at this spot and were met with a great surprise: a barren, rocky island protruded from the water in the middle of the channel. Had they never been there before, this would not have seemed odd. But this was a brand new island that was recently uncovered as the nearby glacier retreated up the fjord. Up until then, that spot had been covered with ice year-round, and no one had known that a small rocky protrusion lay beneath.
I was fascinated by his story and as I listened, I mentioned the words “ice retreat.” At that, the curator’s eyes lit up and with both passion and relief, he said, “Exactly.” It was clear that he needed us to understand his personal relationship with climate change. This was the first time I had met someone who has been so directly affected by warming temperatures and melting glaciers.
The island hasn’t made it on all the local maps yet, but it now has a name that means something like “the bald one” in English. In fact, this isn’t the only new island that has been uncovered by retreating ice. In the past twenty years, Steenstrup Glacier in northwest Greenland has also revealed a handful of new islands (2014 article, 2017 article). The effects of climate change in Greenland are complex–both for the ice sheet, the people, and the wildlife. In some cases, melting ice actually benefits certain Greenlandic industries like mining, fishing, or tourism. But shifts in these industries pose new problems and controversy. This guide to climate change in Greenland discusses what a warming climate means for people and for animals, and what new challenges may arise. Whether you’re a museum curator in Greenland or you’re somewhere else in the world, the effects of climate change will become more complex, more personal, and more prevalent. The burden of our future climate may seem daunting, but there are some small, every-day changes we can make to lessen our negative impacts. Check out this BBC article, Ten simple ways to act on climate change, to see how you can make a difference.
Please welcome Carmi, a new guest blogger here at Time Scavengers!
Carmi here –
In April, I was one of the trip coordinators for the spring meeting of the Florida Paleontological Society. The Florida Paleontological Society is a collection of professionals, amateurs, and every fossil enthusiast you could possibly imagine from all around Florida- and beyond! The society’s mission is to encourage and educate people on Florida’s rich paleontological history.
Usually, trips consist of field collecting (all over the state!), a series of talks given by paleontologists, and a silent auction, with many fossil goodies. In addition to being a member of the society, I also serve as the secretary, which means that I organize membership applications, coordinate trip logistics, and edit the newsletter… among other things.
The first evening of the trip is typically a dinner with all the members who have arrived early for the meeting. It is an optional event, but it acts as a time for folks to catch up and discuss topics of interest with each other. Following dinner, and a good night’s rest, we set off to the quarry to begin the day’s work.
The formation where we looked for fossils is the lower Miocene Torreya Formation (roughly 23 million years old), a limestone deposited when Florida’s sea levels were much higher. This unit is generally thought to be marine, though there is discussion as to the exact nature of the depositional environment – if you are curious to dive into the literature, GeoLex (one of my favorite ways to compile background literature on a geologic unit) has more publications on the Torreya Formation.
After we had our brief geologic and faunal overview, we set down the hill to begin the search. With the constant rain over the days leading up to the trip, the trip leaders were concerned that getting stuck in the clay rich sediments would be an issue – thankfully, the folks from the mine had smoothed out a portion of the road so that access to the collecting site was not too difficult. Small spoil piles were everywhere, full of all kinds of marine fossils, from shark teeth to impressions of different clams and snails.
One fun fact about the site: while many mines in Florida process material for road base (the material that makes up the highways that transport Floridians all over the state), this mine collected and refined clays used in the production of kitty litter!
The evening portion of the meeting took place at the Florida Geological Survey, who graciously accommodated dinner and our evening events. I gave a talk on my current research project – fossil cephalopods from the Cenozoic of Florida. Victor Perez, a graduate student at the Florida Museum of Natural History, was the other invited speaker and spoke on his dissertation research. Finally, the Assistant State Geologist, Harley Means, gave a talk on the history of the survey, and the services that the survey provides to the citizens of Florida!
After the talks, Harley led interested members throughout the survey, highlighting their museum of Florida fauna and amazing library. Inside the library, there were publications on geology of Florida as well as geology from all around the country. Not only does having these publications assist with understanding of similar earth systems elsewhere, but it acts as a way for state surveys to keep in touch and keep aware of developments in geologic mapping and other functions across the country.
Following the tour of the survey, the silent auction began. Items donated by club members were laid out on tables and folks would silently bid on what they found interesting or loudly dissuade others from bidding on these purchases. All the proceeds from the silent auction support student research in paleontology. My strategy is usually to team up with someone on a pile of publications – last year I won a vintage paleontology textbook, and this year I picked up a copy of my beloved Pliocene Mollusca, by Olsson and Harbison (which is another post entirely). After fierce competition, the auction items went home to various members – almost everyone left the auction with something exciting and new.
Of course, the activities were not over for the officers of the society – there was clean-up and then a board meeting the following day. However, trip participants agreed that it was a great experience.
When the students were on spring break a few weeks ago, I decided to take a few days off to go fossil collecting. The first site I went to was the spillway for the reservoir in Caesar Creek State Park. This is a special place for me: it’s the first site we went to collect fossils from during my paleontology course when I was a junior in college. I’ve been going back to this site for about 14 years, but I hadn’t been since 2013, when Jen, Adriane, our friend Wes, and I all went on a long weekend. During this time, Adriane and Jen were helping Alycia Stigall build the Ordovician Atlas. If you are interested in learning more about the organisms found, rock outcrops, and more head to that website!
This site is exposed Ordovician limestone and shales (click here to learn more about types of rocks), representing warm, shallow marine environments. Three rock formations are exposed: Waynesville, Liberty, and Whitewater. If you are interested in learning more about rock formations, click this link which will go into detail on formations! Because collecting is restricted to the base of the spillway, all of the rocks are mixed together and it is difficult to tell which formation the specimens come from. When collecting from Caesar Creek, one must obtain a pass from the Visitor’s Center—run by the Army Corps of Engineers—and agree to follow their rules. Probably the most frustrating rule is that one can’t use tools to extract specimens, not even another rock! But, regardless of these rules, this location is safe for individuals and families to come collect.
I was excited to see what would be exposed in the spillway. This was the first warm weekend of the year, and it had rained the day before. I figured fossils would have washed out from the wall and would not be picked over yet. Usually after a good rain you get lots of new fossils coming out of the rock due to the increased erosion of the outcrop. So it may be wet and gloomy but good for fossil collecting! It sure paid off because today was one of the best fossil collecting I’ve ever had at Caesar Creek!
This was the best haul I’ve had from Caesar Creek in a long time. I was not able to collect many of the really cool specimens I found. They were either way too big and/or stuck in a rock and I couldn’t use tools to remove them. I’m glad I got to see so many amazing specimens and take some home!
I recently took my geology students on a field trip to Blowing Rocks Nature Preserve on the eastern coast of Florida near Jupiter Island. This class is my upper level Sedimentary Petrology class made up of mostly geology majors (we mostly study the formation and identification of different types of sedimentary rocks, like sandstone and limestone). I wanted to show you all what we saw!
The rock that is shown here is the Anastasia Limestone, which was deposited in the late Pleistocene, which spanned about 2.5 million to 12,000 years ago. The ocean levels were much higher than they are currently, when this rock was made. We know this because the limestone that comprises the Anastasia was made underwater. Now, this limestone is exposed all along the eastern shore of Florida.
This limestone is really cool because once it was exposed, it began weathering in unique patterns. First, the energy of the waves is breaking the rocks down bit by bit. This is something we call mechanical or physical weathering. You can see evidence of this mechanical weathering by looking at how the rocks get narrower closer to the bottom-the waves usually only reach that point at high tide, so the rock above it isn’t nearly as affected (image 1). This mechanical weathering can make a few different types of features: sea arches (image 2) and sea stacks (image 2) are the kinds of things we can see here.
The cool geology doesn’t stop here though! Chemical weathering (i.e., breaking down the rock using chemicals-the most common one is water) also affects the rocks strongly here. Limestone is easily eroded away in the presence of acid, so any acidity in the ocean water or from rain above can wear away the rock in interesting patterns. Water splashes up on top of these rocks from regular wave action-that water slowly erodes the rock away, leaving small pits in the rock (image 3). However, what makes this place famous are the large pipes that are created from a mix of the chemical and mechanical weathering processes here. These pipes are quite literally large cylindrical tubes that have been worn out of the rock through hundreds of thousands of years (image 4). Water, when it comes in from waves, rushes up through these tubes and explodes out of the top! Sometimes, these can spray as high as 50 feet-hence the name of the park, Blowing Rocks (video 1)! As we go forward into the future, these pipes will continue to grow larger because they are continuously being worn down by wave energy.
There were some cool fossils on this trip, too! If you look closely, you can see lots of trace fossils from creatures who made burrows into the rock (image 5) and you can also see a lot of clam and snail fossils (mollusks!) Many of these fossils are broken up and the edges have been rounded-this is because of the higher energy waves constantly breaking them down (image 6). My students and I also found a living Portuguese man o’ war (image 7)- this isn’t a jellyfish because it isn’t a single organism, but it’s a closely related colonial organism. The man o’ war has long tentacles that can give humans very painful (but rarely fatal) stings. If you see one on the beach, don’t touch it! They are fairly common on the eastern coasts of south Florida, so be warned! All in all, my students had a great time on this trip, and they learned a lot about how rocks can change due to weathering over time. I hope you enjoyed it, too!