At the end of January, I was in College Station, Texas sampling sediment cores from my recent IODP expedition (more to come on that soon!) and editing our science chapters. It just so happened that while I was in Texas, I also celebrated my birthday. Of course, I had to do something extra fun, so my friend and I (who also sailed with me last summer in the Tasman Sea) went fossil collecting!
College Station is a relatively small town in southeast Texas, made famous as it is the home of Texas A & M University. There’s plenty of bars and restaurants, dancing spots and cowboy hats (seriously, I’ve never seen so many people wearing cowboy boots!). But if you know where to look, College Station is also home to another gem: Eocene-aged (~41 million years ago) fossils!
It just so happened that while I was visiting College Station, I was given a 2018 silver Camaro by the rental car company. Needless to say, we were paleontologists cruising around in style! So my friend and I hopped in the car in our best fossil-collecting gear and made the 15 minute trip to find the ‘most fossiliferous site in Texas’. The outcrop itself is under the Whiskey Bridge on the Brazos River, a bit closer to Bryan, TX than College Station, really. The parking area was located near the bridge, which required pulling off the interstate on a dirt road to get to. Once we were there, it was a short hike under the bridge, and we were instantly in fossil haven!
During the Eocene, this part of Texas was covered by a shallow sea, probably between the shore and the shelf-slope margin, with the shoreline estimated to be about 50 miles away. So, this area was never very deep, but comparable to the continental margin of the east coast U.S. today. Because the water was deep enough that energy from waves didn’t reach the bottom, fine-grained sediments accumulated here. Most of the outcrop was very fine-grained and dark in color, which geologists would call a mudstone. The dark color indicates that the rock is high in organic material from animals, plankton, algae, and bacterial that lived in the upper water column when the sea was here. There are also sandstones preserved at this location, indicating that sea level dropped at one point, and that major storms likely brought in thin sands from shore.
It’s partly due to the fine-grained material that tons of delicate, tiny fossils were preserved in the strata. The dominant fossils that can be found at this location are invertebrates, including gastropods (snails), bivalves, scaphopods, bryozoa, and corals. There are few vertebrate fossils preserved, such as shark teeth, gar teeth, otoliths (fish ear bones), and squid beaks. Even rare trace fossils (preserved movements and burrows from animals) can be found, including coiled worm tubes. We didn’t have much time to collect, as we were just supposed to be gone for about an hour over lunch.
Even though we didn’t have much time at the outcrop, we sure did leave with some awesome fossils! Most of what we found were gastropods- species of Pseudoliva, Latirus, Protosurcula, and Turritella. All were small, with some only being about 3 mm in length! There were few clam shells, as they were mostly delicate and fell apart when we tried to pry them out of the sediments. I felt pretty lucky to have found a fish otolith, or inner ear bone (I didn’t realize that’s what it was until I took it out to write this post)! Towards the end of our trip, my friend found a large (~2 inch) shark tooth! It was her first time finding one, so that was pretty thrilling! Content with our finds, we hopped in the car, muddy and happy, to head back to sample cores in College Station.
But unfortunately, that wasn’t the end of our journey that day. After being on the interstate for 2 minutes, I was pulled over by a state trooper for speeding 3 mph over the speed limit. The officer asked us where we were going, and that he was only going to give me a warning. I then had to get out of the car to get my license (it was in my book bag in the trunk, with my fossils) when the officer asked what was in my bags. Happy for the distraction, I enthusiastically showed him my fossils and began prattling on about the Eocene, in hopes he would lose interest and let us go. Instead, he was totally interested in the geologic facts I was spouting at him! He then said, ‘I wondered what you two were doing under the bridge’.
So as it turns out, driving a new Camaro onto a muddy dirt road near a bridge is a great way to gain the attention of state troopers. I’ll be sticking to my muddy, beat up Jeep for future fossil collecting trips 🙂
Click here for a link to field trip guides, fossil ID guides, an outcrop guide, and a link to a paper about the Whiskey Bridge outcrop!
Last summer, I was lucky enough to be chosen as one of the scientists to sail on the International Ocean Discovery Program Expedition 371 to the Tasman Sea (read more about my adventure here). The ship we sailed on, the JOIDES Resolution, left from the port of Townsville, Australia. Because I was already flying to the Southern Hemisphere, my husband and I decided it was the perfect opportunity to take our delayed honeymoon (we had been married two years at that point, but better late than never!). We stayed on Magnetic Island, located right offshore from the city of Townsville for a week, sight seeing, koala-petting (Queensland is one of the few places in the world that allows you to pet wild koalas), and snorkeling.
Being a naturalist and animal-lover, I have quite a lengthy bucket list. One of the items on that list was to snorkel the Great Barrier Reef. Lucky for me, the reef was just a 2 hour boat ride from Magnetic Island! My husband and I signed up months in advance for a snorkeling adventure on the reef, and we were both extremely excited about it! I prepared for the snorkeling adventure by doing extensive research on the reef, learning species of corals, fish, and sharks that are common on the reef, and also what human-made products (such as sunscreen) were harmful to the reef so we could avoid using them the day of our snorkel. But I also had to prepare myself mentally for what I knew was unavoidable: witnessing a reef community in peril.
Before I explain, allow me to dazzle you with reef facts. Reefs all over the world are amazing places (OK, this is probably more of an opinion, but I’m not wrong, right?). They are home to a huge number of animal species, all who interact with each other. Reefs themselves are defined by the community of corals, fish, crabs, etc. that live together. Reefs are located in warm, shallow, clear waters, and that is why they are found in tropical waters. Reefs occur all across the world, but the biggest and most impressive reef, by far, is the Great Barrier Reef. Check out this Google Street View of Heron Island, Great Barrier Reef to see some of the wildlife and coral species that live on the reef.
The Great Barrier Reef (I’ll refer to it as the GBR from here) stretches 2,300 kilometers (1,430 miles) along the Queensland (northeastern Australia) coastline. It covers about 344,400 square kilometers (132,974 square miles) of area, which is approximately the size of 70 million football fields, or the size of Italy. Because of its size, the GBR is visible from space, and is listed as one of the 7 wonders of the world. Together, the GBR is made up of 2,900 individual reefs, and contains 600 continental islands. It also includes about 300 coral cays (cays, or keys, are small sandy areas located near a coral reef) and ~150 mangrove islands (mangroves are an important plant that live along coastlines; their roots offer protection for small fish and animals and help stabilize the soil in which they grow).
The reef itself is home to over 1,625 fish species, which accounts for ~10% of the world’s fish species! The fish rely on over 600 species of corals for protection and shelter. Over 133 species of sharks and rays also inhabit the reef, feeding off fish. Sea snakes slither their way across the reef, with about 14 different species found in the GBR. 30 species of whales and dolphins also visit the warm, clear waters of the reef to raise their young every year. Of the 7 species of marine turtles alive today, 6 can be found in the GBR. Thus, the GBR is a true natural treasure, with its beautiful marine life, vibrantly colored corals, and abundance of geographic features.
Corals first appeared in the rock record ~548 million years ago during the Cambrian Period. True reefs didn’t make an appearance until about 100 million years later, during the Ordovician Period. These reefs were very different from our reefs today, but the point is, they have survived all 5 major mass extinctions in Earth’s history, and have become extremely successful. But all of that is changing today with global climate change. Reefs all over the world are in dying because of us, humans. It is estimated that from 1985-2012, about 50% of the GBR corals have died (De’ath et al., 2012).
Global climate change caused by humans expelling carbon dioxide (CO2), a greenhouse gas, at an accelerated rate is the leading cause of coral reef decline. As our atmosphere warms, our oceans are also warming. The oceans absorb about 93% of atmospheric heat. Although corals thrive in warm waters, they have a very narrow temperature tolerance (most can live in waters no less than 64 degrees Fahrenheit, and no more than 84 degrees Fahrenheit). When waters become too warm for the corals, they become extremely stressed. Prolonged stress leads to coral bleaching events. This occurs when corals expel the algae, called zooxanthellae, that live in their tissue. The zooxanthellae are what give corals their colors, so after expulsion, the coral turns white. Corals can survive without their zooxanthellae for a short period of time, but if they don’t return, the coral then dies. Check out this page and graphic by NOAA to understand more about coral bleaching.
Coral skeletons are made of calcium carbonate, or calcite (CaCO3). This mineral is also what bivalves and gastropods make their shells out of, so it is commonly found in reef environments. As humans pump more CO2 into the atmosphere, the oceans not only absorb heat, they also absorb this CO2 (about 30% of the CO2 released by humans has been absorbed by our oceans). When CO2 is dissolved in seawater, it creates biocarbonate ions, carbonate ions, free hydrogen ions, and carbonic acid (read more about this process on our ‘Ocean Chemistry & Acidification‘ page). The amount of free hydrogen ions, H+, are what causes ocean waters to become more acidic or basic. An increase in H+ ions leads to the ocean becoming acidic, whereas a decrease in H+ ions leads to more basic waters. So as the oceans absorb more CO2, they become more acidic. Calcium carbonate, what corals make their skeletons out of, dissolve in the presence of acid. So not only are the corals stressed from increased water temperatures, it is also harder for them to grow and build colonies because they are dissolving in increasingly acidic waters.
I was well aware of the effects of global climate change on reef communities before I snorkeled the GBR (at this time, one of the worse coral bleaching events was taking place), but I had never seen the effects of human life on the reefs up close and personal. When we jumped off the boat (which was aptly named ‘Adrenaline’) at Lodestone Reef, I was instantly blown away by the wildlife swimming all around me. Sea cucumbers, starfish, and fish were everywhere, as were several species of coral! Elkhorn coral, brain coral, and species of table coral were abundant all around us. I was in total and absolute awe.
But it didn’t take long to find stressed, dying, and dead corals. Healthy corals are vibrantly colored, while some are flesh-colored. Stressed corals experiencing bleaching events are white, and those that are dead appear black. Dead corals will also have wispy bacteria hanging off the skeletons, as they are feeding off the decaying flesh of the animal. My heart sank faster than an anchor thrown overboard when I first witnessed the stressed, dying, and dead corals. Here I was, in the midst of the world’s largest, most wondrous reef, and it was being decimated. Suddenly, I was overcome with guilt: Guilt at not living a more earth-friendly lifestyle, guilt at not talking about the effects of climate change and its effects on reefs more to my students and the public, guilt that humans are carelessly destroying our Earth’s most precious resources. I was, in fact, witness to one of the largest, most extensive mass murders taking place in my lifetime: the death of our coral reefs.
But I’m not one to end on a sad note; rather, I’m hopeful that we can help our reefs (and all marine life) rebound from the damages we have incurred. There are several organizations that are committed to protecting the Great Barrier Reef and reefs all around the world. Some countries have created fishing restrictions and regulations for their reefs to protect the fish and marine communities that inhabit them. The Paris Agreement, a coalition of over 195 countries, was created in 2015 to curb global CO2 emissions (as of writing this post, the U.S. is still a member of the agreement, but has plans to withdraw by November 2020). Scientists are gathering data on our reefs to quantify how fast they are responding to climate change, and are also working with aquariums to regrow species of corals for release back into the wild. As an individual, you can contribute to protecting our reefs in quite a few ways. First, you can actively vote for government officials that have a track record in supporting science and curbing CO2 emissions. Second, recycle. Most of our trash ends up in the oceans, and that leads to another set of problems for marine life. Third, you can reduce the amount of plastics you use in your daily life by refusing straws at restaurants, using reusable bags, baggies, and containers. Fourth, reduce the amount of time you spend driving a car. Instead, take public transportation, ride a bike, walk, or carpool with friends and family. All of these activities reduce your carbon footprint. Lastly, you can donate to foundations and organizations that work to protect our reefs.
Here’s a list of foundations and organizations that are committed to protecting our reefs, and places where you can find additional information about reefs:
I spend my time working on lectures, reading books, or annotating scientific papers. But, every once in a while, I get to collect fossils and do field work. I haven’t been out in the field since June of 2017. On January 13th and 14th of this year, I spent the weekend collecting fossils from Franklin County and Huntsville, Alabama. These areas around the state consists of limestones that date back during Mississippian period (Lower Carboniferous) ~355-325 million years old. These limestones formed in deep waters where at the time the geography of North Alabama was very different.
In these ancient shallows seas was a large diversity of sea life consisting of brachiopods, rugose corals, crinoids, blastoids, bryozoans, trilobites, and even a few early sharks. Now, their remains makeup the Lower Bangor Limestone Formation and the Lower/Upper Monteagle Limestone Formation of North Alabama. On January 13th the crew headed out to collect fossils from the Lower Bangor Limestone Formation. On our way the site, fossil collector Asa and I decided pull over at a local rock outcrop to save time. The outcrop is part of the Hartselle Formation which consists of fossiliferous and oolithic sandstones. Stratigraphically, the Hartselle Formation is right underneath the Bangor Limestone Formation. So, in other words, we were getting close to our main collecting site.
As we pulled up to the lakeshore, we began to pack up our tools and scout around to look for fossils. Limestones slabs were waiting for us to examine and chip away with our rock hammers. At the first site we found many fossils including a few crinoid calyces, trilobite fragments, Archimedes bryozoans, trace fossils, and one small shark tooth. Asa found a beautifully preserved echinoid and edrioasteroid. After the crew was done collecting at site one, we packed up and began to travel to site two of the Lower Bangor Limestone Formation. We pulled up to to the lakeshore once again. This time the men and women split up to look for fossils. Nathan, Asa, and Dylan scouted around to look for fossils.
It wasn’t until about 5 minutes later that I noticed that the the loose sediment on the ground contained a plethora of fossils that the lake water sifted back and forth over time. I spent a lot of my time lying on the ground picking up crinoid stems, ossicles, blastoid thecae (bodies), brachiopods, and even a few echinoid (sea urchin) fragments. After day one was over for fossil hunting, we began to day 2 of fossil collecting. On January 14th, Asa, Jess, and I went to fossil collect in the Upper/Lower portions of the Monteagle Limestone Formation. At location one we stopped by a small outcropping of limestone. We began looking up and down to look for fossils.
I found a good number of blastoids and great pieces of crinoidal limestone. After we collected material from site one, we began to travel to site two. Site two was much better for finding fossils. Asa and I began to inspect the very top of the rock outcrops. Fossiliferous sediment was then collected to sift through and use for educational purposes. I began to look for fossils from the bottom of the outcrop and collected crinoid stems and a large amounts of Pentremites, a common blastoid from the Mississippian. Just as we began to leave, Asa found a tooth from a Carboniferous aged cartilaginous fish called Chomatodus. The trip was a very successful one. We all spent the weekend and collecting fossils and enjoying each other’s company.
This post is about an education outreach field trip I participated in a few weeks ago. Usually when I go out in the field, I’m either teaching undergraduate geology majors, or with my advisor and lab mates to collect samples for research. This trip was a totally different experience for me, my advisor, Mark, and my lab partner, Serena: we took 18 high school students on a day-long field trip to three stops in the Connecticut River Valley of western Massachusetts! I was really excited for this trip, as I do not get to work specifically with high school students very often. The group we took out in the field was a science club from Holyoke High School in Holyoke, MA. This group of students was very diverse, with most coming from Hispanic backgrounds, some of mixed race, and several that spoke Spanish as well as English. But it wasn’t their diverse backgrounds that intrigued me the most, it was their sense of community and friendship, how they treated one another like siblings instead of classmates. This made spending time and getting to know the students all the more special, and made for an amazing day out in the field!
The students started their day with hot chocolate at 8 am before we picked them up and whisked them outdoors! Our first stop of the day was at the Dinosaur Tracks along Route 5 in Holyoke, MA. Here, over 100 dinosaur tracks are preserved in the Early Jurassic (about 200 million years old) Portland Formation accessible to the public. We talked about the paleoenvironment (the ancient environment) of the area and how the tracks were preserved. In short, the rocks here were deposited along a lake edge, where the dinosaurs would visit for a cool drink. The students were excited by the tracks and the beautiful views of the Connecticut River.
Our second stop of the day was a famous outcrop in the valley called Roaring Brook. This spot is really fun as it’s on the eastern border fault that formed in the Early Jurassic as the supercontinent Pangaea was beginning to rift apart. It was at this spot that the Earth’s crust was pulled apart, causing a block of crust to drop down relative to the blocks to the east and west. This formed the Connecticut River Valley of western Massachusetts as it is known today. Roaring Brook is characterized by massive blocks of igneous and metamorphic rocks that are found beside sedimentary rocks called conglomerate. The waterfalls at Roaring Brook are made of the conglomerate, which the students had a wonderful time climbing over!
After Roaring Brook, we took the students to University of Massachusetts Amherst, where we work, to one of our more famous dining halls. The students loved this (and quite frankly, it’s always a treat for us to eat here, too!), and it gave me and Serena a chance to chat with the teachers.
Our last stop of the day was the Beneski Museum of Natural History at Amherst College. This is one of my favorite natural history museums, partly because it holds the world’s largest collections of dinosaur footprints as part of its Hitchcock Ichnology Collection. The students were given a personalized tour around the museum by one of the curators, where they learned about mammoths, mastodons, sedimentary structures, and of course, dinosaurs!
At the end of the day, I found myself reluctant to say goodbye to the students, and eager to work with them again. Before we dropped the high schoolers back at their campus, we gave them a survey to determine if our field trip was successful (did they learn science, did they have fun) and if they had any suggestions on how to improve future trips. Through this survey, we found out that only a few students had ever been on a field trip. This surprised me at first, as I remember going on field trips throughout my K-12 education. Talking with the teachers, however, gave me a more grim picture: public education funding is limited, and has become more so over the years. This is happening in all public education systems across the country. Teachers’ jobs are becoming harder because of these funding issues, but the real losers in the situation are our students. This field trip made me realize how important working with public school students is, as they and their teachers need all the help and support they can get in these times of public education budget cuts.
Thus, we in the UMass Geosciences department are planning another field trip with the students in the Spring to go fossil collecting in New York. Ideally, this will lead to a long-term partnership between the science educators in public school systems and our university.
This past weekend my lab mates, Tim and Michael, and I went to northern Kentucky to do some field work. Our first stop was in Leitchfield, KY to look at rocks from the Mississippian Period (~355-325 million years old). Michael was there to do some locality scouting for his thesis work so he had some very specific goals to accomplish while we were there. He measured some section (measuring the thicknesses of different beds), made interpretations of the past environments based on the rock types, as well as collected sediment samples to look for microfossils. I had the really fun job of simply going and looking for fossils! This locality is super cool because of the amount of fossils that are just sitting in the loose sediment-they’re everywhere! We were all able to surface collect for a while and found some rugose corals (horn corals), bryozoans, blastoids, and millions of crinoid stems.
After Michael completed his work in Leitchfield we continued on to Danville, KY to the Curdsville Limestone. Tim has used this locality in his own research and I wanted to see this locality because it is where some of the fossils I study come from. While I was unsuccessful in finding a paracrinoid (not actually a crinoid, but an asymmetric echinoderm) it was very cool to see the type of locality that they are found in. The Curdsville Limestone is a “hard ground” so any organism that needs to attach itself to hard ground can be found there. This kind of background information is still useful to my own research to see what kind of community paracrinoids were a part of and what kind of environment they lived in. So while I didn’t find what I was looking for I still learned a lot and saw some cool fossils.
This was certainly a fun (and needed) trip. Doing field work is not a crucial part of my research, but it is still nice to tag along with lab mates, see some cool fossils, and get a break from staring down a microscope. I will say though, this was much different from the field work I did in Scotland-it was much more laid back but at least 20 degrees warmer than what I was used to there! Lots of water and sunscreen was definitely necessary. But again, geologists and paleontologists live by the adage that those who have seen the most rocks/fossils make the best scientists. You never know what you will learn or see going in the field, so definitely go every chance you get!
Every now and then (well, as often as I can to be honest), I go fossil hunting with family, friends, and colleagues just for fun! There’s nothing like finding the remains of extinct animals and plants out in the field yourself. Although there are very few places where fossil collecting is prohibited, there are very few state parks and places in the US where it is encouraged. One of these places is Westmoreland State Park in Montross, Virginia.
This very well may have been the first place I found my very first fossil. I remember my dad had taken my siblings and I to the park one Saturday afternoon to play in the Potomac River and in the creeks and marshes nearby. But, once he told me we could find shark’s teeth on the river banks, my eyes were glued to the sand, systematically sweeping the ground in front of me. Lo and behold, I did find a shark’s tooth! And, it was a tooth that belonged to Carcharodon megalodon (or just Megalodon for short), one of the largest sharks to ever cruise the Earth’s oceans!
Stratigraphy of Westmoreland
Westmoreland State Park is known among locals for its fossils, but any Virginia geologists will tell you the real gem of the park is its stratigraphy (well, OK, the fossils too). The oldest sediment that contain the fossils was laid down in a shallow extension of the Atlantic Ocean about 23-25 million years ago, during the lower Miocene. Younger sediments from the Pliocene (~5.3-2.5 million years ago) and Pleistocene (~2.5-0.01 million years ago) were laid atop the older Miocene deposits. Together, these different rock and sediment layers are called the Chesapeake Group. In the study of rock layers (=stratigraphy), a group includes different rock formations, each with their own name. For example, the Miocene formations in the Chesapeake Group (at least in parts of Virginia) are called the Calvert and Eastover formations.
After these formations were deposited, sea level dropped as glaciers on Greenland continued to grow. This allowed for rivers to flow further out into what was once a sea. Rivers are very powerful eroding mechanisms, as they have the capacity to move large boulders and wear down rocks (think of the Grand Canyon; it was made by the Colorado River cutting through the rock over time!) One of the rivers that now flows into the Atlantic Ocean is the Potomac River. This river is now eroding the Chesapeake Group formations, releasing all the fossils that were once contained in the rocks. Thus, some of these treasures wash ashore at Westmoreland State Park for visitors to find!
Fossils of Westmoreland
Over nearly a decade of visiting Westmoreland State Park, I have accumulated hundreds of shark teeth and found tons of other fossils. Some of these include whale teeth, vertebrae, rib bones and ear bones, dolphin teeth, vertebrae, rib bones and ear bones, fish vertebrae, shark vertebrae, coprolites (fossil poop), an alligator tooth, and mammal teeth. Most of these fossils are Miocene in age, but some are from the Pliocene and Pleistocene.
One of the most famous fossils to come out of the Chesapeake Group are those of the baleen whales. Several new species of whales have been found in Virginia in formations from the Miocene and Pliocene. One of these species, Eobalaeonoptera harrisoni, was found only five minutes down the road from my home in Virginia! E. harrisoni is a beloved icon of the area, in which it was found, so a complete cast of the whale now hangs in the Caroline County, VA visitor’s center.
An exciting perk of attending the University of Wyoming for graduate school is the annual Rocky Mountain Field Trip. This year, the geology faculty planned an adventurous trip to Grand Teton National Park and its surrounding areas (Image 1). Over five days, current and new graduate students explored the unique geology of the Tetons by learning about mountain formations, glaciation, and sedimentation in northwest Wyoming. By the end, we were able to develop an understanding of how this stunning area formed, and how it may change in the future.
For the first few days of the trip, we were lucky enough to stay at the AMK Ranch, which is home to the University of Wyoming-National Park Service Research Station. From here, we had a stunning view of Grand Teton National Park’s most impressive features: the high-standing peaks of the Teton mountain range (Image 2). These mountains are tremendously tall (the Grand Teton’s peak is 13,775 feet in elevation) due to a complex tectonic history of extension and uplift. Essentially, the mountains uplifted while the valley to the east dropped down. The pointed horns of the Tetons are a result of glacial sculpting during the Pleistocene Epoch.
One of the best parts of this trip was the variety of geology and geologists (Image 3). We learned about glacial geology, sedimentology, structural geology, hydrogeology, paleontology, and so much more. The professors and guests who joined us along the trip had a massive breadth of geologic knowledge. Not to mention, we were able to explore a national park with a geologic lens. That’s one of the most exciting things about being a geologist; you can look at landscapes with towering mountains and glacial lakes, or with meandering rivers and rolling hills, and you can envision the multitude of processes that formed that landscape.
I recently returned from a five-week field camp in Scotland. Field camp is a course that most geologists participate in that is intended to teach students how to collect geologic measurements in the field, recognize geologic structures like folds and faults, understand age relationships of the rock, and ultimately make sense of all of this by making maps and cross sections (interpretations of what the surface geology looks like underground). Field camps are incredibly important as geology students because it reinforces the ideas that the best geologists are those that have seen the most rocks and that geology needs to be learned outside, not just in the classroom.
So, why Scotland for field camp? Scotland is an interesting location geologically, because for much of Earth’s history it was essentially a ping pong ball with sections of the country getting added on by collisions with other continents as it bounced around. If you look at a map of Scotland you can see two almost parallel lines dividing the country into three pieces (Figure 1). The top most fault is the Great Glen Fault which runs through the city of Inverness and Loch Ness (where the Loch Ness monster resides). The fault further to the south is the Highland Boundary Fault which does divide the country into the Highlands and Lowlands. Each of these pieces was accreted (added on) during a different collisional event. Surprisingly, the last, and youngest, collisional event that happened, when Baltica (Northwestern Europe) collided with Laurentia (North America, Greenland, Scotland), deposited the oldest rocks that you can see in Scotland. These rocks are ~3.2 billion years old and they lay on top of limestone that is ~540 million years old (Figure 2). Seeing this age relationship in the field tells us that something crazy was happening geologically!
Field camp is a lot like summer camp mixed with a typical college class-there is a lot of fun to be had with fellow rock nerds, but also a lot of learning and homework to be done. On a typical day we would leave our hostel or house by 8:30am, work in the field, mapping and collecting data, (either in small groups or individually), leave the field around 5pm, go home and cook dinner for your small group, then work on interpretations of our data and prettying up our maps. Usually at the end of the week we would have a larger project to hand in based on the maps that we had made that week and our interpretations of the area (Figure 3).
Going to field camp can seem daunting at first, especially if you are going on one outside of your home country, but truly is an important experience in learning to be a geologist. Like practicing a sport or instrument, you have to practice geology skills in order for them to become second nature and field camp is the best place for that practice. For a lot of people, this is where geologists have their first “I am a geologist” moment. So, for anyone who wants to be a geologist (or paleontologist or other earth scientist) get outside and look at some rocks and fossils and start observing, because the best geologist has seen the most rocks!
Every Spring, UMass takes its Historical Geology class on a weekend field trip to the Mohawk Valley in New York. The purpose of the trip is to show students the formation of an ancient ocean that once covered North America ~450 million years ago in the Ordovician and talk about the ancient environments that animals lived in. We also take the students to some locations on the second day of the trip to rocks that are a bit younger (~410 million years old) so they can collect fossils. In addition to talking about tectonics and fossils, we also show the students some really great sedimentary structures preserved in the rock record.
The first stop of the day involved looking at older limestones of early Middle Ordovician age in an abandoned rock quarry. At the second stop, we looked at finer-grained shales that were deposited in a deeper portion of the ancient basin. At the third stop of the day, we investigated the Utica Shale, one of the largest shale deposits on the east coast, and one that is commonly targeted by oil and gas companies because it produces these products at the right depths in the Earth. Here, we all found trilobite pieces (and a few whole specimens). The last stop of the day involved walking down to a waterfall on Plotter Kill Preserve (not really a welcoming name for a park) and investigate the shallowing or infilling of the ancient basin. In addition to beautiful scenery, there are also some really great sedimentary structures preserved at this location.
The second day of the trip is always the highlight of the weekend, at least for me! Our first stop was the Lower Devonian limestones of Schoharie, NY, which are highly fossiliferous. After we spent a few hours at this locality, we took the class to a locally famous locality called the Taconic Unconformity. Here, rocks of Middle Ordovician age (~460 million years old) are against Lower Devonian rocks (~410 million years old), meaning that a huge chunk of time (the entire Silurian Period) is totally missing. The unconformity is really apparent because the older Ordovician rocks are standing almost straight up, whereas the Devonian rocks are less tilted.
The last stop of the field trip was to another locally famous and well-loved locality called ‘Dinosaur Skin’. This name is wildly misleading, as the rocks here were formed about 250 million years before the first dinosaurs roamed the Earth, although the sedimentary features preserved in the rock do resemble dinosaur skin. Instead, the features preserved in the rocks at this location are called flute casts, which are a type of sole mark, a sedimentary feature that is formed and preserved on the bottom of sedimentary beds. In the Middle Ordovician, there were intense storms as well as earthquakes as other pieces of continents and island arcs collided with the east coast of ancestral North America. These caused sediment instability in the form of turbidites, which can be thought of as underwater landslides. So, the Dinosaur Skin is actually scoured sediment that was preserved in the rock record.
This past weekend several students, myself, and my lab mate Maggie went to a fossil locality near Hopkinsville, Kentucky. This rock is from the Mississippian and this locality is particularly interesting to me because of the amount of blastoids you can find in a single moment. They are falling right out of the rock! So we went with a specific question to answer. We are looking to better understand the gap in fossil preservation within some of the blastoids there. Let me explain some – there are specimens that range from 0.25 – 15 mm in height. But most scientists ignore everything below 5 mm because it falls apart more easily than the larger specimens.
Recently we have examined some of the very tiny (0.25 mm) specimens and we are interested to see how the growth of the organism may be affecting its ability to preserve in the rock record! So we did some surface collecting – looking around on the ground and picking up specimens that we can see with our eyes. We also did a lot of bulk collecting. By bulk collecting I mean we filled buckets of sediment with a shovel to take home with us. We will then sieve all the sediment to differentiate the different sizes of the specimens. We will have several different sieve sizes from 5 mm all the way to 64 microns (very tiny material). We will clean everything so that we can sort through the different sizes to find what we are looking for – pieces of small blastoids!
The fossils are found in limestone beds (see by Maggie’s leg – there is a bench like extension from the rock) and in the shale layers (drab gray colored rock that makes up most of the bottom) that occur between the limestone beds. The big rock on top of them is sandstone and is part of an ancient river system.