Excursions with Tennessee’s Governor’s School

Maggie here-

This past June, I helped teach biology, with a focus on vertebrate evolution, with Tennessee’s Governor’s School, a program for high school students to come and experience college life for a month. Last year, Time Scavenger mastermind, Jen, wrote a post about what Governor’s School is, so I’m going to focus on the field trips that we went on!

Figure 1: Here we all are out in front of the entrance to the Gray Fossil Site! In addition to having a lot of information about the fossil site itself, there is a very hands-on science museum at the site.

Field trips are a really important part of learning about science, but can also be really valuable in showing young students what careers are available to scientists. Most students understand that scientists have all kinds of different research interests and biologists don’t spend their days rehashing high school biology curriculum, but it can be hard to imagine what else you would do with a degree in biology without seeing it in action. So, to show our students what all biology encompasses, we went on four field trips this year to the Gray Fossil Site, Oak Ridge National Lab, ProNova, and fossil collecting in east Tennessee!

Our first field trip was to the Gray Fossil Site, a Miocene (4.9-4.7 million years ago) fossil assemblage. This site is really cool because it is a lot younger than most fossil sites in east Tennessee and they have a plethora of vertebrate fossils preserved there. They have found everything from tapirs (similar in look to a pig) to alligators, mammoths, and even a new species of red panda! We unfortunately went on the paleontologist’s day off, so we didn’t see anyone actively working at the site, but we could see the pit that is being excavated this summer as well as peek into the preparation labs to see which fossils are currently being cleaned and put back together. After our tour we had some time to explore the museum that is a part of the Gray Fossil Site which does a good job of explaining what the preserved environment is like, how the site itself was discovered, and what the roles are of the scientists involved at this site.

Figure 2: An image from ProNova’s website showing how protons can more directly target a tumor when compared to radiation therapy. By more directly targeting a tumor, the patients risk of developing complications (including different cancer later on) from healthy tissue being exposed to high levels of radiation, decrease dramatically.

The second field trip that we went on was to Oak Ridge National Lab. We are super lucky living in Knoxville that we have a national lab ~40 minutes away that is welcoming to visiting groups! Since we were talking about biology, our main tour was in the biofuels (fuel derived from living matter) lab. There we discussed the major setbacks to biofuels (large land areas needed to grow plant matter to turn into biofuels, making sure that the carbon footprint of the growing and production of biofuels was also lessened, etc.) and how scientists at Oak Ridge are trying to solve these problems to make biofuels more readily accessible for large-scale use. In addition to biofuels, we met with other scientists and talked about big data and the computing power of the supercomputers housed at Oak Ridge. There’s nothing like talking about supercomputers and all that they can to do to get a bunch of science nerds buzzing!

Our third field trip was to ProNova, a facility that is using proton therapy to fight cancer. This field trip was particularly exciting to our students because many of them want to go into the medical fields, but was also a great learning experience for me! Using protons to treat cancers is a relatively new treatment, so none of us had any idea of what to expect, or what we were going to learn. At ProNova, they use large electromagnets to generate a beam of protons that can be directed to target tumors and that beam has more control than radiation, so only the tumor is being “attacked” by the protons, not the tumor + healthy tissue. The coolest part of this field trip was being able to go behind the scenes and see the magnets and resulting beamline that then is directed into treatment rooms and eventually into patients!

Figure 3: Left: One of the receptaculites specimens that was found while we were fossil collecting. You can see in the image on the right how similar they look to the center of a sunflower!

Our final field trip was to go fossil collecting in east Tennessee. While we weren’t collecting vertebrate fossils (east Tennessee is chock full of lovely invertebrate fossils-I might be a little biased in calling them lovely!), many of our students grew to appreciate paleontology over the month-long course and were excited to be able to collect their own fossils to bring home. Most everyone found crinoid stems, receptaculitids (an algae that looks a lot like the center of a sunflower), and bryozoans (small colonial organisms). We also stopped to look at a wall that was made almost entirely of trace fossils!

While we spent a lot of time in the classroom discussing vertebrate evolution and all of the different aspects of science that play a role in understanding how life and humans evolved, our field trips provided our students with real world applications for the science that they were learning. And from my perspective, the field trips were a way to get ideas of how to present this kind of material in my classroom, as well as to collect current research examples to help answer questions of why biology and vertebrate evolution are important to our understanding of the world! Governor’s school is a really intense month for both the students and the teachers, but the field trips gave us all a chance to connect and have candid conversations about science. It also gave me a chance to reflect on the field trips I took as a young scientist, and how they shaped my desire to become a scientist–so remember, field trips may appear on the surface to be just fun and games, but are incredibly important to the learning process!

Urban Fossil Hunting

Mike and Jen here –

Figure 1

I couldn’t believe what I was seeing. I was on a tour of campus for my paleontology course, and Dr. Sandy took us to a low retaining wall in front of the Science Center. There it was: a large Pentamerus brachiopod (Fig 1). I’d walked by this wall for years and never noticed it before! During the rest of the tour, I saw fossils all over campus, and I had never even thought to look for them in the building materials.

Ever since then, I’ve taken closer looks at the stones used in buildings to see if there are fossils. You should, too! But ignore the igneous rocks and marble, just go for the limestone, dolostone, and sandstone pieces. The fossils I’ve seen include trace fossils and body fossils. Trace fossils are fossilized behavior of an organism, whereas body fossils are the actual skeletal or imprint of remains.

Figure 2

Primarily, I’ve encountered trace fossils. The Dayton Limestone, a formation found near Dayton, Ohio, is Silurian-aged (443.8-419.2 million years ago) limestone that was used for building foundations all over the state. It is full of burrows that are highlighted by a lining of hematite (Fig 2). The hematite likely came into the burrows after the organisms were done occupying them. This mineral helps the burrows stand out in the rock. The foundation on the left is a building on the campus of the University of Dayton. The founding on the right is a building in downtown Springfield.

Figure 3
Figure 4

Further exploration for urban fossils led me to find trails on the base of a lamppost outside of one of the courthouses in Springfield (Fig 3). I forgot a scale for this picture, but these trails were about 10 cm in length. I found this next burrow (Fig 4) in one of the retaining walls outside of the library at UD. See what I mean about fossils in places you wouldn’t expect them?

Marine animal body fossils are quite easy to find in building materials. I found these Silurian fossils in a retaining wall near some of the older buildings on UD’s campus. Large brachiopods and gastropods may be found in these stones (Fig 5), as well as colonial corals and horn corals (Fig 6). Sometimes it is difficult to recognize the fossils because the animal is within the rock and you are only getting a two-dimensional view of what it looks like.

Figure 5
Figure 6
Figure 7

Sometimes, the fossils can be very small and hard to pick out from the rock they are in. I walked by this wall for nearly 15 years and never noticed all of the gastropods, bryozoans, and crinoids until just a few weeks ago (Fig 7)! Another example of small fossils was found by Jen when she went to the Biltmore Estate in Asheville, North Carolina. She was chatting with her family when she looked down and recognized the rock, it was filled with small gastropods and bryozoans that she knew to be Mississippian (360-325 million years ago) in age (Fig 8).

Figure 8

Be sure to be on the lookout inside of buildings, too! Many building stones are made of fossiliferous rocks and they are quite visually appealing so they end up as table tops, counters, and even bathroom stalls! Jen saw this table, made of polished fossiliferous limestone, inside of the Biltmore house (Fig 9). I found these ammonites in the flooring at the Ohio Statehouse (Fig 10). Each side of the tile was about 2 ft in diameter.

Figure 9
Figure 10

Where Jen lived in Eastern Tennessee, the common limestone is called the Holston Limestone. This is the ‘marble’ that gave Knoxville the name of Marble City. Marble is a metamorphic rock whereas limestone is a sedimentary rock. Sometimes limestone can have really small grains that makes it look like marble. As a local rock it is used all over the city in a variety of places. It decorates the exterior of buildings downtown (Fig 11) and is even sculpted into monuments of past events (Fig 12).

Figure 11
Figure 12

Maggie and Jen went on a recent research trip to Oklahoma and noticed something interesting about their window sill in the kitchen (Fig 13). It was a nice pink color with lots of white specks. It happened to be the Holston Limestone from where they both were living in Eastern Tennessee! This rock has very specific features that allow you to identify it wherever you may be. Jen even discovered this rock in an old hotel (now a university) in St. Augustine, Florida.

These just a few examples of the fossils that we have seen used in construction and design. As you walk around city buildings, be on the lookout for limestone blocks, especially on older buildings. There may be a few fossils hiding in plain sight!

Figure 13

Bathroom Geology

Do you ever see pictures of beautiful geology all over the world and think “WOW, I don’t think I’ll ever be able to see that in person”? Well, think again. This post is dedicated to helping you find amazing geological finds in a place I can guarantee you will visit just about every day: the bathroom (and no, I’m not just talking about coprolites)!

The goal of this post is to teach you a little about the types of rocks you might see the next time you’re in a restaurant bathroom, a bathroom at the beach, the library bathroom, or even the bathroom in your own house! You might be thinking “oh, but what can I learn from a bathroom?!” Well, you just might be surprised. So, let’s get to learning!

Figure 1. A granite countertop from a restaurant in Richmond, Virginia. This granite is unique because of the concentric zoning of the crystals- this means that the crystals were cooling at slightly different temperatures, giving it the unusual appearance of the larger crystals (where my finger is pointing). Different elements are crystallizing out of the magma at different temperatures, which gives it this look of almost like tree rings.

Our first stop is a small restaurant in Richmond, Virginia. The food was good, but the real treat was finding the granite countertops inside the bathroom (Figure 1)! Take a look! Granite is an intrusive igneous rock: meaning, the magma from which the rock was made cooled slowly underground. We know this because of the very large crystals that we can see! Crystals grow from the liquid magma; the longer they take to cool, the larger they grow. Now, let’s look more closely at these big crystals. If you look at the large, light pink colored crystals where my finger is pointing you might see that they are what we call “zoned”- meaning, there are alternating circles of slightly different colors inside the crystals- their rounded shape means we’d assign the term “concentric zoning” to them. This actually tells us something really cool about their cooling temperature!

Figure 2. Bowen’s Reaction Series explains the pattern of what minerals and elements cool at what temperatures. As magma cools, certain materials are always crystallized first and pulled out of the pool of magma. Photo credit: National Parks Service

Magma cools at different rates- depending on where it is on Earth or the types of materials from which the magma is made. This rate of cooling determines how and when certain minerals form, or crystallize. In other words, geologists know quite well at what temperature a mineral will form within a magma chamber as it cools down. This predictable pattern of mineral formation with cooling temperatures is called Bowen’s Reaction Series (Figure 2). When this happens, it means the chemistry of the still-liquid magma changes quite a bit!
To put this into a more delicious and more relatable example, think about a giant jar of Starburst-with red, pink, yellow, and orange evenly mixed in. Let’s say you give this jar to me (I really love Starburst). I will preferentially eat all of the orange ones out of it; then the pink; then the red; and finally, we’ll only be left with yellow (gross, who eats the yellow ones?!). We’ve changed the overall composition of the magma (i.e., the jar of Starburst) by preferentially pulling out one type of material in a specific pattern. Now, take a look at the giant crystal my finger is pointing to- the zoning is going back and forth between a sodium and a calcium rich solution in the feldspar (the name of the mineral)-this indicates that the temperature of the magma where this was cooling was changing slightly, alternating between a little hotter and a little cooler.

Figure 3. This granite has almandine garnet as an accessory mineral, which means that the magma from which it formed had a lot of aluminum in it!

Now granite is really cool and it’s a very common bathroom countertop, so let’s look at another example (Figure 3)! This granite was part of a larger piece of rock that was installed in a private home bathroom in Fayetteville, North Carolina. This little piece was leftover, so the countertop store let me have it! This granite is similar to the granite from above, but it doesn’t have any zoning, meaning it all cooled without any weird changes in temperature. However, it does have one pretty cool feature-the garnets! These garnets (the little red crystals) are of the almandine variety. Almandine is a type of garnet that has a lot of iron and aluminum in it. Garnet forms in granite as an accessory mineral (meaning, not a major component) and different garnets can mean different things. In this particular sample, this almandine garnet means the magma was aluminous; meaning, there was a lot of aluminum in this magma!

Figure 4. This migmatite formed from the combination of an igneous and a metamorphic rock; this rock also has ptygmatic folding, which is seen in the lighter layers as the squiggles running across the rock. These form from high temperature and pressure and from one of the rocks being much more viscous than the other (in this case, the lighter rock is much more viscous than the darker rock- much like honey is more viscous than water).

I found this gem at a women’s bathroom in the San Francisco airport (SFX) last year (Figure 4)! This rock is called a migmatite. A migmatite is unique in that it is a cross between an igneous (formed directly from cooled magma or lava) and a metamorphic rock (a rock that was exposed to heat and pressure after its original formation). The dark and the light material you see here are from two totally different processes. The light material here is mostly quartz (the same mineral that we call amethyst or rose quartz–quartz occurs in a variety of colors). The lighter material is much more viscous-meaning, it resists flowing (like honey or molasses), while the darker stuff (primarily from minerals called pyroxene or hornblende) has a lower viscosity and flows more easily. Now, do you see how the light colored material exhibits small and irregular folds? These folds are what geologists call “ptygmatic”. These ptygmatic folds generally occur at pretty high temperatures and pressure; these variables cause the layers to fold and buckle the way that they do because of the differences in viscosity. The high temperature and pressure, along with the high viscosity of the light material, will cause these types of folds to form (these are also known as “passive folds”).

Figure 5. Internal and external molds of fossils at the St. Petersburg beach bathroom! These form when the actual shell of a creature is worn away and all that is left is the mud that either filled the inside of the shell or the mud that formed around the shell.

I recently saw this one (Figure 5) at the St. Petersburg beach in Florida, pretty close to where I live. These blocks are part of the public bathroom walls and as you can see, these bathroom walls are chock full of fossils! Wow! These fossils are from Florida and they’re pretty recent–no more than 10-20 million years old. They’re also primarily mollusks, the large group that contains octopuses, clams, snails, and oysters. Imaged here are snail fossils-you can identify these snails by their long, delicate shells- and clam fossils-you can identify those by the much larger shells that have ridges along the edges. These types of fossils are called “molds”-this means that the shell itself has been worn away and all that’s left is the sediment that either filled in the shell or the sediment that formed around the shell. The internal molds are where you can see an actual 3D shape of the inside of the shell, whereas the external molds are where you only see an impression of the shell.

Figure 6. Labrodorite is a type of feldspar that has an easy to recognize iridescent sheen. Labrodorite is most commonly found in mafic igneous rocks, like basalt!

Last but not least, my mom snapped this picture of her bathroom just for this post (thanks, Mom!)! Labradorite is a beautiful mineral-it’s a type of feldspar, which is in the same group as the lovely pink minerals seen in the granite in Figure 1. What makes labradorite so different, though, is that this feldspar doesn’t form in granite-it forms in a very different type of rock, like basalt! Basalt is an extrusive igneous rocks, so it forms from lava that cools at the Earth’s surface. Basalt is found in places like Hawaii, where it comes out of volcanoes, or at mid-ocean ridges, where new seafloor is being made. Basalt is mafic, meaning that it is full of heavy minerals like iron and magnesium. Labradorite is famous for its iridescent sheen-you can see it here in Figure 6!

I hope that this post has shown you that you don’t need to travel to fancy and far away locations to see real and beautiful geology up close. Sometimes, interesting geology can be as close as the nearest bathroom! Next time you see one of these counters, stop and take a look! What do you see? Do you see fossils? Garnets? Zoning? Do you see something entirely different? Before I go, I’d like to thank geologists Cameron Hughes, Zachary Atlas, Elisabeth Gallant, and Jeffery Ryan for help with identifying some of the details in these rock samples!

Field Work on the Greenland Ice Sheet, Part 2

Part 2: An Attempt at Science

Megan here-

If you haven’t read Part 1 of my Greenland field work experience, check it out here! If you have read it, you’re probably wondering what research we actually worked on for those three chilly weeks. What were our research goals? What type of data did we collect? And how did we collect that data? To answer those questions, I give you Part 2: An Attempt at Science.

The University of Wyoming and University of Montana’s glaciology group has become highly involved in Greenland Ice Sheet (GrIS) research over the past decade. Because the ice sheet has become of critical importance in our warming climate, many scientists are trying to better understand the dynamics of the GrIS. Our collaborative group asks questions such as, how does meltwater move through the ice sheet? What mechanisms are involved in ice sheet movement? Or, what conditions lay beneath the ice? Answers to these questions help us to better understand GrIS dynamics in a changing climate.

Figure 1. Glaciers are divided into different regions based on the processes and conditions of those areas. The ELA is the equilibrium line altitude where there is no net accumulation or melting. The ablation zone is at lower altitudes and defines the margins of the ice sheet where melting occurs. In contrast, the accumulation zone defines the area where there is net accumulation of snow. Within this zone is the percolation zone, where there is some melting and we see extensive layers of firn.

For this field season, we were mostly concerned with the first of those questions. More specifically, we ask: what is the fate of meltwater in the percolation zone? To better understand what the percolation zone is, let’s take a look at the different regions or zones of a glacier (Figure 1). Any glacier (or ice sheet) is divided into two main parts: the ablation zone and the accumulation zone. The ablation zone defines the lower elevations where there is net melting. In other words, over a year-long period this region has lost mass. The opposite is the accumulation zone. Here, there is net gain in mass due to snowfall. These two zones are divided by the equilibrium line altitude (ELA) where the amounts of accumulation and melting are equal. This may seem straightforward at first glance, but a rather unusual region exists within the accumulation zone. Just higher in elevation than the ELA, there is a section of the glacier where snow melts and percolates into the firn. Firn is just altered and compacted snow. We’re curious about the fate of meltwater in the percolation zone’s firn. When snow melts to water, does it flow into the firn and refreeze? Does it percolate all the way down to the glacial ice layers? Or does it runoff toward the terminus (“the snout”) of the glacier and reach the ocean?

Figure 2. We used a hot water drill to penetrate the upper 100 meters of the firn at our study site. The drillstem is attached to a long hose, which carries hundreds of gallons of hot water from a tub to the borehole. As the hot water is blasted at the cold firn, it melts the firn and creates a borehole.

To answer these questions, we used a variety of research techniques that look at the structure and temperature of the firn throughout the full depth of the percolation zone, which is thought to be less than 100 meters thick in this area. The five principle tools we used were coring, hot water drilling, videography, temperature sensors, and radar. Coring involves extracting long cylinders of snow, firn, and ice from the ground below us, and then logging the densities and structures of the core. To reach greater depths than with coring, we used a hot water drill to inject hot water into the ground and create a borehole (Figure 2). Once we had a completed 100-meter borehole, we extended a video camera down the hole to visual identify interesting structures (e.g. ice layers) in the firn. In both the hot water-drilled boreholes and the boreholes remaining from coring, we installed long strings of temperature sensors that measure and record the firn temperatures at increasing depths. These temperature data will be recorded for the next year or two, so we will return next summer to collect the data. The final technique we use, ground-penetrating radar, provides insight into the firn layers below our feet. By transmitting radio waves into the ground and then receiving the waves, we can observe variations in firn density and estimate water content. Together, these five techniques provide a means to better understand the behavior of meltwater in the percolation zone.

Before arriving in Greenland, I was highly intimidated by all of the research techniques we had planned to use. I had never been involved in a full field season, never cored or drilled firn, and never even stepped on a glacier for that matter. However, I found that the best way to learn something is to actually just try doing it. With the guidance of a patient and knowledgeable advisor, I learned more than I thought was possible in three short weeks. Being in the field provides such an excellent opportunity to take an immersive approach to science: living, working, and learning in the presence of what you study.

The Bay of Fundy, Part 2

High tide at the Sea Caves in St. Martin, New Brunswick. Far out in the distance are quite large caves, but you can’t see them due to the high tide!

This is the final post in the series of the geology of Maine and the Bay of Fundy. To recap for those of you who might not have read my first post, I documented all the geology I saw recently on a vacation my husband and I took to Maine and New Brunswick, Canada. This is the second post all about the geology of the Bay of Fundy! This one, though, will talk about the famous rocks of the bay and how they got the unusual shapes that made them famous. Remember, the Bay of Fundy is famous because it has the highest tides on Earth.

Scenic photo of an overlook at the Fundy National Parkway

So what do these tides do to the rocks? To answer this, let’s first go to St. Martin, to the famous Sea Caves. You might be looking at this first image and think “what caves!”? Well, this first image is taken at high tide, so the caves are almost entirely underwater. High and low tide were separated by about six hours, so we saw high tide, admired the lovely scenery, and drove to see the Fundy Trail Parkway, a park that you can drive or hike the entire way through for some GORGEOUS scenery. There are spots to pull over and get out, hike short distances, or just look out from a cliff to see some beautiful sites. Here’s a picture overlooking the Bay of Fundy – remember, these lovely coastlines were largely created by the formation, movement, and melting of glaciers.

Low tide at the Sea Caves in St. Martin. This is taken at the same distance from the caves as the image from high tide.

We returned to the Sea Caves to see it at low tide-take a look! This picture is from the SAME spot, give or take a few feet. This photo should show you the height and amount of water moved by tides every day in the Bay of Fundy. The presence of these caves is due to mechanical weathering-literally, the waves associated with the tides coming in and out are quite strong and they break down the rocks. Thousands of years of these waves have created immense caves and crevasses. Once you are able to walk across the seafloor at low tide, you can truly appreciate just how incredibly large these caves are and just how strong the tides are! Here’s an image of me inside one of the caves!

I’m standing at the very back of one of these sea caves!
As we walk across the seafloor, you can see how large these cave systems really are-they’ve been created by thousands of years of strong wave action, something we call mechanical weathering.

There’s one last thing I want to point out about these tides-the effect that they have on living creatures! Snails and barnacles live in high abundance all over the area affected by low tide and these creatures find incredible ways to survive when the low tide means that they aren’t covered by water! Snails will gather in small cracks in rocks where water will pool; barnacles will form more in shadier areas, so the rocks will remain more damp than those exposed to the sun. Sometimes, snails will hang on to a piece of algae just to survive until the water comes back! Check out this image of a snail holding on for dear life!

Snails have methods to survive low tide-this snail is clinging to a piece of algae to survive until the water comes back into the area. This picture makes me think of Jurassic Park and the famous line “Life, uh, finds a way”

Now, let’s travel north to Hopewell Park, where the most famous rocks from the Bay of Fundy are. First, let’s look at the difference between low and high tide. These images are taken just about 4 hours apart. So the rock you see here was broken off from the cliffs due to chemical weathering-water percolating through cracks and breaking them apart. But, the odd shape that you see now, where the rock is much narrower on the bottom-that’s due to mechanical weathering. Wave action over thousands of years has caused these shapes to form. These rocks CAN fall without warning (and have, even recently), so park rangers are always making sure to look for signs of instability.

Low tide at Hopewell Rocks. These rocks are HUGE!

To really experience high tide, my husband and I signed up to kayak through these rocks. To say that the waves here were strong is an understatement! The waves were cresting at just under 4ft-so imagine sitting down on the beach front-you’d be completely covered (if you were curious, kayaking in 4ft waves and high winds was a blast, but also a little terrifying!)! Here’s an up close picture of that same rock you saw in the previous two pictures, from the kayak! Now you can really see where the rock is narrowed at the base-the line between the narrow and wider part of the rock marks the highest the tides can go.

High tide at Hopewell Rocks. Park rangers have to close this off quickly when the tide starts coming back in, to prevent people from being swept in the strong waves.

I hope you’ve enjoyed this series! I think one of the most important things I can say here is that this trip made me rediscover my love of geology. Sometimes, when you work long hours every day as a geologist, it can become a little hard to remember just why you love it. If you’re feeling that way, I encourage you to get out and go explore for a little while- a few hours, or even a few months, if you can!

An image of the rocks from the kayak at high tide. Take a look at how wave action has shaped this rock, from how it narrows at the base and has a large crack in the center.

Geology of the Bay of Fundy

Sarah here –

Map of the Bay of Fundy. The reason why the tides are so high is because the bay gets very narrow, so all of the water going into the bay has to go vertically. Image from Bay of Fundy Tourism.
This post is a continuation of my first post, the geology of Acadia National Park. To recap for those of you who might not have read my first post, I documented all the geology I saw recently on a vacation my husband and I took to Maine and New Brunswick, Canada. This post will be all about the geology of the Bay of Fundy! Specifically, this will be about how glaciers have shaped the geology of the area.

The Bay of Fundy is an incredibly famous geologic area for a good reason-it has the highest tides on Earth, with the highest reaching nearly 56ft! The reason why the tides are so high here has to deal with the shape of the bay-the bay narrows quite a bit (as you can see from the map), so as all the water enters the bay, it’s forced to stack up on top of each other, making the tides reach these incredible heights.

The wave energy at this part of the Bay of Fundy is very high. We can tell because the sediment there is almost entirely very large rocks, as opposed to sand!
Glaciers have shaped a lot of the geology along the Bay of Fundy; as glaciers advance and retreat, they leave telltale signs. One of the best signs are when you see rocks called tillites. These rocks are made of glacial sediment. They’re fairly easy to recognize-often, you’ll see rocks with very large, poorly sorted clasts (meaning, all kinds of different sizes of sediment). These are left behind by glaciers! Here is an example of tillite along the coast of the Bay of Fundy. Look at all of the different sizes of clasts in there! This rock was found at the Irving Nature Center, St. John, New Brunswick. The wave energy in this particular area is very high, which you can tell by the lack of small sand grains and the prevalence of much larger clasts (pebbles-boulders). Another sign of glacial activity is the presence of striations on rocks. Striations are scratches in rocks that are caused by glacial ice moving over them. These glaciers can have lots of rock and sand debris within it, so as they move over rocks, it can cause a lot of surface damage to the rock. Check out this picture of striations on volcanic rocks, also from the Irving Nature Park!

Striations caused from glaciers scraping across a rock surface
Arguably, the most famous area of the Bay of Fundy is the site called Hopewell Rocks. I’ll discuss a lot more about the Hopewell Rocks in my final post, but for now, let’s talk about how glaciers shaped these famous rocks. As glaciers last retreated from these areas (meaning, the Earth warmed and glacial ice melted), the water from the glaciers filled into the ground and caused cracks to form along the coast. This is called chemical weathering. Water is a chemical and it’s the most common chemical that rocks come into contact with when we’re talking about chemical weathering. These cracks eventually caused these large rocks to be separated from the cliff line. This phenomenon might be more familiar to you when you’re driving- when roads (in colder areas, especially) have small cracks in them and water gets into those small cracks, that water can freeze, causing the crack to expand. After multiple rounds of freezing and melting, these cracks become a real problem to drivers!

Glacial melting caused the rocks along parts of the Bay of Fundy to crack (due to chemical weathering) and break off. Here’s a photo of some of these rocks at the famous Hopewell Rock site!
During our next (and final) piece about my trip through the Bay of Fundy, we’ll look at how these famous rocks are shaped by mechanical weathering, instead of chemical!

This rock, called a conglomerate because of the multiple large clasts within it, is indicative of a glacial environment.

Acadia National Park Geology

Sarah here –

My husband, Joe, and I at Acadia National Park!
I recently went on a trip with my husband to Maine, USA and New Brunswick, Canada to see some of the best geology these places had to offer! I’ll be showing you a lot of the gorgeous geology (and some cool biology!) through a series of posts. This first post will be all about my trip to Acadia National Park. My husband and I hiked quite a few trails (about 20 miles of trails total!) in the four days we were there and we learned quite a lot about the geology of the park from our adventures.

Here I am climbing the Beehive Trail, a famous trail in Acadia. It follows a path up and down a mountain composed of granite.
A lot of the rock you’ll see in the popular parts of Acadia- especially the trails in the main part of the park-will be granite. Granite is an igneous rock that formed intrusively, meaning, it formed under the surface of Earth. You can generally tell whether igneous rocks formed intrusively or extrusively (on Earth’s surface), because the sizes of the grains will be different. The magma that makes up granite cools very slowly under the surface of Earth-the slower it cools, the larger the crystals are! But, I digress. Many of the mountains in the Acadian region are made of granite. This granite was formed when two continents- Laurentia (North America) and Avalonia (eastern North America and western Great Britain) slammed together hundreds of millions of years together. When they collided, it forced a huge amount of magma to pool, creating the famous granite we see today (you can read a lot more about the creation of Acadian rocks at this site)! Here’s a photo of me climbing some of this granite on the Beehive Trail! The mountain is very steep and the trails are very narrow, so it is most safely climbed using metal ladders!

View from the summit of Beehive Trail. Gorgeous!
Granite is a very hard, stable rock. What that means is that it doesn’t weather away easily, like other rocks (think of how marble gravestones look like after a few decades-marble is much more easily worn down!) But after millions of years, even the toughest of rocks can start to be broken down! Take a look at these rocks here-you can see the cracks from being weathered (likely by rain!)-these cracks allow rain to penetrate into the rock and break it down even faster! To put it into perspective, think of a windshield-if you put a single crack into it, you’ve weakened the glass and further pressure can result in faster spreading of the break. Rocks respond similarly after the first cracks are formed!

Schoodic Point. This gorgeous part of Acadia is shaped by a dramatic coastline, formed by granite and altered by darker volcanic rock intrusions
I want to show you some of the cool pictures from the other side of Acadia now. This is a lesser known, but just as beautiful part of the park as the most well known part of Acadia. This area is called Schoodic Point. This is also dominated by the same gorgeous granite-but it’s got something else going on that’s really spectacular. If you take a look, you’ll see the gorgeous light colored granite…but also, intrusions of a dark colored igneous rock (called a diabase); this diabase has tiny crystals-meaning, it cooled quickly! We can tell that the dark colored rock intruded into the granite because of the Principle of Cross Cutting Relationships; this geologic principle means that if a rock “cuts across” another rock, the rock that is cutting across is younger (read more about geologic principles here).

An up-close look at just one of the diabase intrusions-some are massive! Some are much smaller.
So, with that in mind, these diabase intrusions are the remnants of later episodes of volcanic activity. There are multiple episodes of volcanic activity represented here-many of the intrusions are cut by even more intrusions! What a beautiful place. So even though this is a post about geology, I wanted to show you a little bit of the life here at Schoodic Point-the wave activity at this area is VERY high (one easy way to see that is that there’s very little sand at this coast-the wave energy is too high, so the sand gets washed away). The water crashes up onto the granite and some water will stay up there, giving a perfect spot for lots of little critters to form a home! Take a look at this small pool of water-how many critters can you see?

Here’s some of the life living on the rocks-the water is washed up from the waves and lots of critters will settle in here. Can you see barnacles, bivalves, snails, tiny crabs, and algae? Anything else?

Stay tuned for more posts on the rest of my trip!

Japan Temple and Metamorphic Rocks

Jen here –

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.

Field Work on the Greenland Ice Sheet, Part 1

Part 1: Living in an Unlivable Place

Megan here-

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.

The Black Hand Sandstone of Ohio

Kyle here –

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.