Scavenging the fossil record for clues to Earth's climate and life
Field Excursions
This page is where we will post any research, academic, or just-for-fun field work we do. The idea is to show you, the readers, what we do as paleontologists in the ‘field’.
Rinsing our hands in the river before nearing the shrine. Notice the dark coloration of the stairs. These are some of the greenschist rocks at the complex.I experienced a more non-traditional field experience that I would like to share with everyone. I recently traveled to Japan for the 16th International Echinoderm Conference and during this conference there was a mid-week field trip to the Ise Grand Shrine. Before we left we were given a brief history on the shrine and what it symbolizes. Basically, it is meant to symbolize eternity. This shrine is rebuilt every 20 years from the ground up rather than patching issues as they arise. This ensures that the shrine ages as a whole! It is also built adjacent to the current standing shrine so every 20 years the shrine moves locations.
The primary shrine at the temple complex.The shrine is built of very specific building materials and no nails are used during the construction. The rebuilding of the shrine ensures that the next generation learns the skills required to construct the temple to continue to pass along this tradition. It’s a really interesting concept and I really enjoyed getting to wander around the complex. There were also very interesting rocks as you walked up to the shrine!
The steps were mostly made of metamorphic rocks that are likely greenschist. This type of metamorphic rock is created from igneous rocks that undergo transformation under particular temperatures and pressures. The heat and pressure often comes from different land masses colliding with one another throughout time, caused by plate tectonic movements. Greenschist rocks are normally dominated by minerals that exhibit a green color such as chlorite, actinolite, and epidote. Japan has an incredibly complex tectonic history and I won’t attempt to explain it but if you are interested in learning more check out this report and the Geology of Japan by the Geological Survey of Japan. Close up of some of the stairs containing the greenschist rocks.
Whenever you are traveling or even in your hometown, make sure to look out for what buildings, stairs, and more are made of! You’ll be surprised at the extraordinary details you will uncover in the rocks that surround you in your daily life.
The tent glows orange as the sun shines in, waking me up to a cold, crisp morning. Only, it’s not really morning yet. It’s 3:00 AM and far from breakfast time. The wind rattles the thin flaps of my tent, reminding me of the powerful cold outside of my warm haven. This is the Greenland Ice Sheet. This is the icy expanse where the summer sun barely sets, the temperatures are well below freezing, and the wind can numb your face. This is also where I work.
I recently returned from three weeks of field work on the Greenland Ice Sheet (GrIS) where I helped collect data for the University of Wyoming and the University of Montana’s glaciology group. Our collaborative group consists of two lead professors (one at each university) and a handful of graduate students, postdocs, and associates. This year, six of us flew to Greenland to collect data for our ongoing study of ice sheet dynamics. This was my first field season on the GrIS, and it was like no other experience I have ever had.
Where did we go?
Nestled between the Arctic and the Atlantic Oceans lies an icy mecca for glaciologists: Greenland. Greenland is an island almost entirely covered by an ice sheet, which is a body of glacier ice that covers a very large area (greater than 50,000 square kilometers). Today, ice sheets blanket both Antarctica and Greenland (Figure 1; at left). If the GrIS were to melt it could raise sea level by an astounding 7.2 meters (Church and Gregory, 2001). With such potential for catastrophe in a warming climate, the GrIS has become the center of many studies investigating glaciology, climatology, oceanography, and much more.
Our group set off for the GrIS with the goal of better understanding meltwater flow in the accumulation zone. This is a region of the ice sheet where there is net accumulation of snow. We set up our field site on a snowy spot called Crawford Point (Figure 1, in black square). Aside from a weather station on the horizon, the views were the same in every direction: a flat white ground and a clear blue sky. Of course, that was on a “good weather day.” We had our fair share of days when ground blizzards prevented us from seeing more than a few feet ahead, or when clouds rolled in and the world around us became an empty whiteness.
Figure 1 (on the left) is of the sites of interest in Greenland. Kangerlussuaq (indicated by the yellow circle) is a small municipality of about 500 people. Located next to the ice sheet, Kanger (for short) occupies a flat region at the eastern end of a deep fjord. In fact, Kangerlussuaq translates to “big fjord” in Greenlandic. During WWII, it was founded by the U.S. and used as a U.S. airbase. Though no longer an active military base, Kanger is the site of Greenland’s largest airport and is almost entirely dependent on tourism. Our field site (Crawford Point) sits within the square on the ice sheet.
How did we get there?
Figure 2. (A) An Air National Guard C-130 plane flew us from Schenectady, New York to Kangerlussuaq, Greenland. (B) A Twin Otter plane flew us from Kangerlussuaq to our field site, Crawford Point. Both this plane and the C-130 have skis so they can land on snow. (C) The view from the C-130 as we flew into Greenland showed a dynamic coastline with many mountains and glaciers. (D) Many outlet glaciers of the ice sheet could be seen as we flew from Kangerlussuaq to Crawford Point.
From the United States, the journey to the GrIS is rich with excitement and with boredom. Most of us flew into Albany, New York and then took a military flight to Greenland. The Stratton Air National Guard Base runs periodic flights from Schenectady, New York to Greenland with their C-130 planes (Figure 2). These are training flights, which means that the pilot and the on-board mechanics are practicing ensuring that these planes run perfectly. Because of that, successfully leaving the base took two days and a few attempts. At one point, we departed on the plane and flew for about an hour before turning around and landing. Finally, we arrived in Kangerlussuaq, which is a small town on the southwest coast of Greenland (Figure 1).
In Kangerlussuaq, we worked for a few days as we prepared our gear and instrumentation for a successful field season. A massive amount of planning and work goes into field preparation, because once we’re out on the ice sheet, there’s little chance of deliveries or spare parts. When our day to fly out to the site finally came, we were ready. A Twin Otter plane (Figure 2) flew us an hour and a half from Kangerlussuaq to Crawford Point. We needed four flights to bring ourselves and all of our gear to the field site, and three flights to leave.
What’s it like to live and work on an ice sheet?
Figure 3. Our camp consisted of one cook tent (orange dome), six personal tents (extending linearly from the cook tent to the right), and a work tent (not pictured). This photo was taken before the wind piled up many feet of snow around our tents.
Life on the ice sheet is thoroughly unusual. At Crawford Point, we set up six personal tents, a cook tent, and a work tent (Figure 3). We also dug out a latrine in the snow, which we covered with a tarp to keep out of the wind. The latrine experience was…interesting, to say the least. We actually used our core barrel, which is designed to extract cores of snow and ice, to create a toilet (Figure 4).
Figure 4. We used a core barrel to create the toilet in our dug-out latrine. After the toilet was complete, we covered the latrine with a tarp to block the wind and snow.
Each day we’d eat a modest breakfast and lunch together, and then we would take turns cooking dinner on our Coleman camp stove. The meals became somewhat repetitive, but I appreciated having a warm and filling dinner after a day’s work. However, by the ended of the trip I detested beef jerky, I couldn’t eat another bite of cheese (which is saying a lot, because I love cheese), and all I could think about was a fresh, green salad. Still, I was grateful to have sufficient food while living in a wildly unlivable place.
Aside from the hundreds to thousands of meters of ice and snow that cover Greenland, what really makes the ice sheet uninhabitable is the weather. The cold air and blistering wind demanded rather intense clothing and gear. Every day I wore gigantic triple-layer Baffin boots, wool socks, a thermal base layer, fleece-lined pants, snow pants, a pullover fleece, a heavy jacket, a neck warmer, a hat, thick gloves, and either polarized sunglasses or ski goggles. Getting ready in the morning was quite the feat. One of the many challenges was actually completing work while wearing so many clothes. I would often have to pull off a glove to tighten a small screw, or shed a few layers after I warmed up from shoveling.
Figure 5. Here I stand in front of the Russell Glacier, an outlet of the GrIS. Calving (a process by which glaciers shed icebergs) leaves behind clean faces of blue glacier ice. The river running along the glacier appears thick and milky due to the large quantity of sediment that it carries.
Luckily, after our three weeks on the ice sheet, our remaining time in Kangerlussuaq was warm and sunny. We took a day and drove out to the ice sheet margin (yes, you can do that), where we hiked to the Russell Glacier (Figure 5). Standing at the edge of the ice sheet was a humbling and breathtaking moment. The ice glowed blue, the milky river roared as it flowed next to the glacier, and an occasional crash could be heard as the glacier calved into the flowing river. This one moment shifted my perspective of so many things. Those three weeks of field work, the months of lab work, and these couple of years of my master’s finally fit in a bigger picture that I could see right before me. And in that moment, the struggling graduate student in me found the motivation and confidence I needed to keep working, learning, and progressing.
Stay tuned for Part 2 where I discuss the scientific work we completed!
References
Church, J.A., Gregory, J.M., 2001. Changes in Sea Level, in: Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P.J., Dai, X., Maskell, K., Johnson, C.A. (Eds.), Climate Change 2001: The Scientific Basis, Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, pp. 639–694.
Geology is the physical manifestation of time. The rocky foundations of our planet are the consequence of billions of years of natural processes, many of which continue today. The record of this extensive history is visible not only as layers of rock, but also in what is missing. Although often unnoticeable on human timescales, steady erosion by wind, water, and ice is a tremendous force over millennia. And across millions of years, entire mountain ranges can be uplifted, ground down to their roots, and the resulting sediments compacted into rock and uplifted into mountains anew.
By definition, gorges and canyons are among the best places to view the results of erosion, often combining exposed bedrock with more superficial—but no less interesting—features carved by running water. The bedrock may also record evidence for its own intriguing origin, adding more layers to the story (pun only half intended). The American West is well known for such exposures, the Grand Canyon foremost among them, but the East and Midwest also have their share, most cutting through Paleozoic strata: Letchworth Gorge and Niagara Gorge in New York, the Kentucky River Palisades and Red River Gorge in Kentucky, and many others.
Ash Cave, a spectacular rock shelter in Hocking Hills State Park. Unlike a true cave, rock shelters represent superficial erosion of a rock body. They typically form where stronger rock overlies softer rock. The softer rock erodes more readily than the overlying rock, forming an overhang.
Ohio has a number of notable gorges, many easily accessible to visitors within regional or national parks. Clifton Gorge, in John Bryan State Park near Dayton, cuts through Silurian strata that are age-equivalent to those at Niagara Falls. Numerous small gorges and valleys near Cleveland slice through Upper Devonian, Lower Mississippian, and Lower Pennsylvanian rocks, including the great Cuyahoga Valley (and its eponymous National Park). And south-central Ohio is home to the Hocking Hills, where great sandstone cliffs form ridges, gorges, and natural bridges within a lush, relatively undeveloped forest.
The Upper Falls at Hocking Hills State Park.
Situated near the western edge of the Allegheny Plateau, about 45 miles (~70 kilometers) southeast of Columbus, the Hocking Hills expose shales and sandstones of Late Paleozoic age. Unlike the northern and western regions of Ohio, this area was not beveled flat by glaciers during the Pleistocene and thus retains a rugged topography. Hocking Hills State Park, as well as a variety of other nearby nature preserves and local parks, is the iconic centerpiece of this scenic area, a popular destination for hikers and other nature enthusiasts. The park contains numerous gorges, waterfalls, “caves”, and cliffs, all worn out of a picturesque orange to tan sandstone.
This rock is the Black Hand Sandstone. Early Mississippian in age (roughly 355 million years old), the Black Hand is a coarse, sometimes conglomeratic quartz sandstone. It is massive in nature, without many discrete beds or major changes in its consistency. However, a number of features are visible at some localities, including cross-bedding, the angled bedding of ancient ripples or dunes, and graded beds, where layers of coarse pebbles transition upward into layers of smaller pebbles and then into sand, an indication of sorting by water.
Large scale cross-bedding in the canyon walls near Old Man’s Cave in Hocking Hills State Park. Cross-beds indicate directional movement of sediment as ripples or dunes migrate over time.Prominent liesegang banding in the Black Hand Sandstone at Clear Creek Metro Park, southeast of Lancaster and not far from the Hocking Hills.
Another common feature of the Black Hand is liesegang banding, concentric, sometimes twisty patterns of rusty staining. In contrast to cross-bedding and graded beds, which show evidence of what was going on at the time when the sand was deposited, liesegang banding formed much later, as groundwater percolated through the sandstone, carrying iron and other minerals with it. These minerals precipitated out of solution over time, forming the colorful bands. This can be seen as a form of weathering, rather than rock formation, though the distinction is rather blurred in this case as the bands can comprise lumps and stringers that are more resistant than the surrounding sandstone.
Cedar Falls at a trickle. Though deceptively calm in this photo, the falls rushes whenever there is rainfall, as evidenced by the smoothly carved sandstone channel.
A number of waterfalls that cascade through the local gorges, including the Upper and Lower Falls near Old Man’s Cave as well as the nearby Cedar Falls. These falls have cut smooth channels into the Black Hand.
A roadcut near US Highway 33 south of Lancaster, exposing the grey-ish shales, siltstones, and fine sandstones of the upper Fairfield Member of the Cuyahoga, capped by the orange basal Black Hand.
Geologists consider the Black Hand Sandstone a member of the Cuyahoga Formation. The sandstone’s lower contact is apparently erosional, with the sandstones of the Black Hand cutting down into the shales and siltstones of the Fairfield Member of the Cuyahoga Formation below. Meanwhile, the top of the Black Hand is capped by thin conglomerate, the Byrne Member of the Logan Formation. The Logan is also sandstone-rich, but less massive than the Black Hand below and may have been deposited in deeper water.
The tall cliffs downstream of Old Man’s Cave impose their shadows on the gorge below.
Several hypotheses have been put forward to explain the origin of the Black Hand. One suggests that it is a part of a great delta, deposited offshore in the shallow sea that blanketed the midcontinent during the Mississippian. Another proposes that the Black Hand is in fact a channel itself, formed in an estuary or river that carved its way through the underlying strata during a brief episode of low sea level. In either case, the relatively large and well-worn quartz pebbles and sand that make up the sandstone must have come from land to the east, near what are today the Appalachian Mountains. Research on this matter is ongoing at the Ohio Geological Survey and elsewhere.
Black Hand Sandstone in Black Hand Gorge, Licking County, Ohio. No swimming!
While Hocking Hills may be the most famous exposure of Black Hand Sandstone, it is by no means the only one. The name was coined for prominent exposures of the rock along Black Hand Gorge on the Licking River east of Newark, Ohio. (The Gorge itself is so-named for a Native American petroglyph featuring a large black hand that was once emblazoned on one of its sandstone walls; sadly, this rock art was destroyed by 19th century construction in the Gorge. The name may also be spelled Blackhand, but the split version is preferred herein.)
Thus Black Hand Gorge is the type locality of the Black Hand Sandstone, the primary place that geologists should refer to when determining what the Black Hand Sandstone is, what it correlates to, and other questions. Although the process of naming rock units is now codified by the rules of the International Commission on Stratigraphy, rock units were less rigorously defined in the 19th and early 20th century. Additionally, some localities that once provided excellent exposures are now gone, naturally weathered away, covered by vegetation, flooded, or destroyed by later human development.
The trail through Black Hand Gorge. This exposure is actually man-made, blasted in the 1800s for a railroad that once ran along the gorge. It is near a quarry complex adjacent to the natural gorge. The Black Hand Sandstone was once widely used as a building stone.
Fortunately, the Black Hand is still well exposed in its type area, easily accessible from a hike-bike trail that follows the Licking River through the gorge, passing sandstone cliffs, fallen boulders, and old quarries. In addition to the Gorge itself, nearby roadcuts afford excellent views of the sandstone cliffs to casual observers.
True Black Hand Sandstone is only exposed in Ohio. However, some other sandstones in nearby states are believed to be of a similar, perhaps even equivalent, age, including the Burgoon Sandstone of Pennsylvania and the Marshall Sandstone of Michigan. Elsewhere, such as in northern Kentucky, the same timespan is represented by shales and is much thinner. It is sobering to note that the time period that forms towering cliffs in central Ohio is elsewhere represented by just a meter or so of mud or, in others, by nothing at all.
An imposing cliff of Black Hand Sandstone along Ohio State Route 16 east of Newark, Ohio, not far from Black Hand Gorge itself.
Similarly scenic sandstone gorges are exposed throughout the Midwest, including the previously mentioned Red River Gorge in Kentucky and Turkey Run State Park in Indiana. However, these sandstones are typically younger in age than the Black Hand, often Pennsylvanian, deposited as the American midcontinent sea was shrinking into oblivion.
Massive section of Black Hand downstream of Cedar Falls in Hocking Hills State Park, probably tens of meters high. But this is nowhere to be seen when you leave the Black Hand outcrop area, perhaps evidence that its deposition was restricted to channels in a specific region.
A simple location map (inset) and aerial view of the Whiskey Bridge fossiliferous outcrops on the Brazos River.
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!
My snazzy rental car I drove around College Station !
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!
A view of the outcrop on the Brazos River, under the Whiskey Bridge. Notice how fine-grained and dark the sediments are towards the bottom, then get coarser (chunkier-looking) towards the top. The coarser-grained sediments indicate a sea level fall.
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.
A close-up view of the fine-grained sediments that contained fossils.
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.
A small preview of the fossils found under the Whiskey Bridge on the Brazos River. All of these fossils are invertebrates, except the rounded fossil at top center; that is a fish ear bone!
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!
A view of Queensland and its coastline in northeastern Australia (inset image). The Great Barrier Reef is the long feature, highlighted by the white lines, that stretches along the coast. Images from Google Earth (2017).
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.
A rare sight: An on-the-move koala family on Magnetic Island.
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.
Lodestone Reef, a small reef part of the Great Barrier Reef that we snorkeled.
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.
A colony of healthy table coral with striped damselfish swimming about.
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.
A solitary (one animal that lived by itself rather than in a colony) horn coral, one of the earliest species of corals from the Ordovician. Image from the Digital Atlas of Ordovician Life.
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.
My husband swimming next to a healthy community of various coral species. Some of the corals at Lodestone Reef are enormous, which indicates the coral is probably decades old.
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.
Elkhorn corals in various stages of bleaching at Lodestone Reef. The fleshy-colored coral at the top of the image is healthy, the white coral directly under it is bleached, and the dark coral with bacteria feeding off the dead animal is at the bottom of the image.
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.
Stratigraphic chart in the area we were collecting in.
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.
Debbie and Asa looking for fossils in the Lower Bangor Limestone Formation.
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.
Asa and I inspecting the Lower Monteagle Limestone Formation Site 1
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.
Upper Monteagle Limestone Formation Site 2
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.
The echinoid Archaeocidaris hemispinifera that was found by Asa.Four Asteriacites (star fish resting traces fossils) found by Jess.Petaldus tooth. Found by Jess.Blastoid (Pentremites sp.) that I foundChomatodus sp. tooth
Serena and I with one of the dinosaur trackways. The tracks are next to our hands on the left side of the image.
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!
Mark explaining to the students how we concluded that this area was once an ancient lake. If you look carefully, you can see fossil ripple marks in the center of the image!
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!
The students exploring the conglomerate rocks at Roaring Brook.
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!
The students are given a brief overview of the Beneski Museum before looking around. Smilodon (a Pleistocene saber-toothed tiger) is in the foreground.
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.
Picture from the outcrop in Leitchfield, KY. This really demonstrates just how packed this outcrop is with fossils. Visible here are many bryozoans and crinoid stems, but we also found blastoids and rugose corals. 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. Daedalocrinus (extinct crinoid) from Danville, KY. This locality is known as a hard ground so any organism that needed a hard substrate to attach themselves to would have lived here.
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!
An aerial view of Horse Head Cliffs at Westmoreland State Park overlook the Potomac River. The beautiful parallel layers of sediment contain fossils. Image courtesy of the VA Department of Conservation & Recreation.
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
Sifting for fossils on the banks of the Potomac River.
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
A small C. megalodon tooth found at Westmoreland State Park.
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.
The cast of Eobalaenoptera harrisoni that can be visited in the Caroline County, VA visitor’s center. Image from the Virginia Museum of Natural History.
Image 1. Grand Teton National Park (in the red ellipse) is located in the northwest corner of Wyoming, just south of Yellowstone National Park.
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.
Image 2. The view from AMK Ranch stretches across Jackson Lake to the Tetons. This photo looks southwest and shows the northern part of the north-south trending range.
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.
Image 3. New and returning graduate students, UW professors, and even the UW provost mimic the pointed peaks of the mountains on a hazy day in Grand Teton National Park. Photo courtesy of Robert Kirkwood.
