Teaching about Traces as Evidence

With the start of a new academic year, many university professors might be deliberating on what they’ll be teaching, and many students similarly (and hopefully) might be wondering what they will be taught. For me this academic year, my plan is not to put so much emphasis on the “what,” but more on the “how,” and put it in the form of a basic question: How could I be wrong?

In my experience, this is a question we professors and other educators we often ask, regardless of whether we are in the natural sciences, social sciences, humanities, or some blend of those educational realms. Now, this is not to say that we should continuously live our lives in doubt of our hard-earned skills and knowledge, succumbing to imposter syndrome. So what I will suggest is that we use it in our teaching, leading by example for our students. For instance, when my students see me question an initial interpretation of mine, correct that wrong interpretation, and show delight when this happens, then they will feel more comfortable asking themselves the same question, too.

So how do I apply this method to my research disciplines of paleontology and ichnology? If I am observing a natural phenomenon in the field, museum, or other settings, and I find myself jumping to a conclusion too rapidly, I take a moment to pause, back up, and try to disprove that hasty conclusion. Sometimes it turns out that, yes indeed, I was an idiot. But if this debunking process fails to find anything terribly wrong with my original explanation, or I modify it accordingly in the face of newly acquired evidence, then I’ll think this: So far, so good.

Eight-Legged-Otter-TracksWhoa, check out the tracks made by this eight-legged river otter! This eight-legged otter must have been the result of some freak mutation, or genetic engineering, or joined twin otters, or a robot spider with otter feet…What? Was it something I said? (Scale in centimeters; Photo by Anthony Martin.)

Moreover, because so much of paleontology and ichnology involves interpreting the products of non-witnessed lives, behaviors, and environments, such as bones, shells, leaves, tracks, and burrows, careful documentation of this evidence is key for making reasonable interpretations. Because we can’t prove ourselves wrong by watching a video of whatever happened in the pre-human past, we also have to ensure that the evidence can be shared and evaluated by other paleontologists and ichnologists.

In the following video, I explain these two basic scientific principles – how could I be wrong, and so far, so good – by using a few examples from a forested area next to the Emory University campus in Atlanta, Georgia. This is the place where I often teach first-year (freshman) students in a small-class seminar how to track the animals on and around our campus. Because most of these animals are nocturnal, most remain “invisible” to the students’ during their four years on campus. So my students really do learn how to use trace evidence to make reasonable hypotheses about animal presence and behaviors, and by the end of the semester, they get pretty good at it.

This sort of educational fruition is what made for the most fun part about doing this video, which was having a former student of mine who took the class four years ago play the role of my willing and eager “student.” In this, we demonstrated how the two basic principles – how could I be wrong, and so far, so good – are applied when in the field. It actually wasn’t much of a stretch for my former student, as Dorothy (Dottie) Stearns (Emory College ’16) was one of my best students in the class when she took it, and she really enjoys getting outside and tracking, so her enthusiasm is genuine.

The video is part of a series that Emory is producing on the theme of Evidence at Emory, with professors from a wide variety of disciplines explaining how they incorporate evidence-based reasoning in their courses. First-year students at Emory are the specific target of the videos so they are exposed to different disciplines and how scholars evaluate evidence in those disciplines. But there’s also hope that students will retain these discernment skills in life after college. Nonetheless, I think anyone who likes observing and thinking about what they observed can benefit from watching them. I could be wrong on that, but if not, I’m fine with that, too: for now.

Eight-Legged-Otter-TracksWait a minute, you’re saying these tracks could have been made by two otters, with one following closely behind the other? Huh, hadn’t thought of that. But that doesn’t mean eight-legged otters aren’t out there somewhere. Or freak mutated otters. Or genetically engineered otters. Or a robot spider with otter feet. What? Was it something I said?

Acknowledgements: Thanks to the Quality Enchancement Plan of Emory University for encouraging me to more overtly incorporate evidence as a main theme in my class, to Dottie Stearns for being such an awesome student/actor, and to the Center for Digital Scholarship, also of Emory University, for their fine work on the video production.

Looking for Traces in an Ordovician Sea

It might seem a bit strange to consider traveling back 450 million years as a “homecoming.” But geologists time travel often enough to qualify as Time Lord apprentices, regardless of whether we are traveling by phone booth, car, or on foot. What creates this situation is how geologists may experience much of their training, teaching, or research interests in rocks of a certain age, gaining a certain comfort level when dealing with the earth of that time.

Cincinnatian-Outcrop-2“Hey everyone, let’s go to the Ordovician!” “Sounds good to me. Road trip!” You can do this when you live in a place with abundant, fantastically preserved, and freely available fossils. Which incidentally describes the area around Cincinnati, Ohio. (Photo by Anthony Martin.)

For me, my most recent homecoming was to the Ordovician Period, a geologic time span of about 488-444 million years ago. As a geologic period, its life and marine environments are represented quite well by the world-class fossil-bearing limestones and shales in and around the area of Cincinnati, Ohio. This is where I gained my formative training as a paleontologist, as I studied Ordovician rocks and fossils in the area while working on an M.S. degree in geology at Miami University in the mid-1980s. (Incidentally, Miami was a university before Florida was a state, and the rocks around it are much older than any in Florida, too. As a matter of pride, then, I like to inform people that I went to the “real” Miami.)

So last month I was lucky enough to participate in two field trips and a paleontology mini-conference in the region of Cincinnati, Ohio, which felt very much like a homecoming. The field trips and conference were co-sponsored by: the myFOSSIL Project, an NSF-funded initiative working to unite avocational (“amateur”) fossil collectors with professional paleontologists while enhancing STEM (Science Technology Engineering and Math) through the science of paleontology; The Dry Dredgers, a fossil-collecting club founded in 1942 (!) in Cincinnati, and consisting of some of the most knowledgeable and enthusiastic collectors I’ve met anywhere; the Cincinnati Museum Center, which hosted the conference and keynote talk (more on that soon); and the Paleontological Society, which was ably represented at the mini-conference by their current president, past president, and other officers and members.

Cincinnati-Musum-CenterExterior of the Cincinnati Museum Center, which helped to host the Paleontology Mini-Conference, houses a fantastic collection of Ordovician-age fossils, and served as the venue for a keynote talk given by Yours Truly. The museum building originated as the Cincinnati Union Terminal in 1933 and was later converted into the museum in 1990. It’s a very neat place for both its art-deco architecture and its displays, and every visit to the Cincinnati area should include it. Right after having some Skyline Chili and Graeters Ice Cream, that is. (Photo by Anthony Martin.)

Already I’ve listed many reasons for being there, but the main incentive was as the keynote speaker for the mini-conference, an invitation I received and gratefully accepted late last year. For that, I gave a public lecture at the Cincinnati Museum Center on a Friday night, and on the topic of my most recent book, Dinosaurs Without Bones (2014). I had my usual fun time with the lecture, the audience had a variety of thoughtful questions for me to answer and otherwise discuss, and I happily did a book signing afterwards. We were then given a tour of the museum, which has world-class Ordovician fossils in it and much more.

Sound great? It was. But the real highlight of my journey was seeing the Ordovician rocks and fossils in the area. Hence I had to participate in the pre-meeting and post-meeting field trips to various roadcuts in Kentucky, Indiana, and Ohio while there. As an ichnologist, I was was also keenly interested in revisiting the trace fossils in these rocks, which I had not seen in a long time (by human standards). Accordingly then, the following photos show some of the people and outcrops we visited, but really focus on the coolest trace fossils I saw, accompanied by my attempts to explain each.

Many thanks to everyone who made the 2016 Cincinnati Paleontology Mini-Conference happen, and much appreciation for taking me back “home” to the Ordovician.

Dry-Dredgers-Carl-BrettThe pre-meeting field trip and part of the post-meeting trip benefited from the presence of the indefatigable Dr. Carl Brett from the University of Cincinnati. I am continually awed by both his knowledge of the Ordovician rocks and fossils and his unrestrained enthusiasm for sharing this knowledge. Even better, he loves trace fossils, which officially makes him my new best friend. (Photo by Anthony Martin.)

Cincinnatian-Outcrop-1Roadcuts like these, all chock full of Ordovician body fossils and trace fossils, make me and other paleontological connoisseurs very happy. (Photo by Anthony Martin.)

Rusophycus-CincinnatianCarl Brett found these gorgeous trilobite resting traces at the very first outcrop, which at first made me a little jealous, but I got over it quickly enough after staring at these beauties for a few minutes. These were probably made by a species of Flexicalymene, which burrowed down into a firm mud below, possibly to hide from predators but also as shelter from other problems above. Later, silt and fine sand filled in the depressions, making these natural casts. Be sure to look for the little trilobite tracks, too.

Small-Cruziana-CincinnatianHow about the cutest trace fossil I saw? Here’s a tiny trilobite burrow I found on the bottom of a siltstone bed (my thumb is pointing to it). The dual pathways mark where its little legs pushed down and into the sediment below it; it have been made by a juvenile or full-sized adult that just happened to be really small. It is again preserved as a natural cast, so you’re looking at the bottom of the bed. (Photo by Anthony Martin.)

Palaeophycus-CincinnatianMost of these trace fossils are compressed and intersecting horizontal burrows, which are  visible because they are filled with a different sediment than the surrounding rock. Notice smaller-diameter and more complicated burrow system to the right, which apparently was made first, as the other burrows cut across it. Both were likely feeding burrows made by worm-like animals. (Photo by Anthony Martin.)

Diplocraterion-Palaeophycus-CincinnatianAt least four different types of trace fossils are on this slab: the little “pockmarks” that also show some branching; the lined burrow toward the top of the slab (eroded so that it looks like a snail trail); the long, discrete burrow just above the scale, and the “dumbell” one on the lower right. Applying the principle of cross-cutting relations, can you work out the sequence of which burrow came first, second, third, and last? All were likely made by wormy critters and are feeding burrows, although the “dumbell” burrow also served as a home, as we’re looking at the top of a U-shaped burrow. More on that with the next photo… (Photo by Anthony Martin.)

Diplocraterion-CincinnatianThe trace fossils on this surface are similar to that of the previous one, but has a lot more “dumbells,” which represent U-shaped burrows that were originally tubular, with the critter – maybe a worm, maybe a crustacean – having its head close to one opening and its rear end close to the other. To visualize these burrows in three dimensions, make a “U” with your thumb and forefinger, turn it so you are looking at the tips of your fingers, and imagined a line of collapsed sediment between the two limbs of the “U.” (Photo by Anthony Martin.)

Diplocraterion-Spreite-CincinnatianThese are bottom expressions of the U-shaped burrows, but omitting the tubes. The curved lines inside the linear parts show where the maker of the U-shaped burrow moved its burrow up or down in response to what was happening on the surface. A little confused by that? You’re not alone, and welcome to my world. (Photo by Anthony Martin.)

Diplocraterion-Cross-Section-CincinnatianHere are partial vertical sections of two U-shaped burrows, with the one on the left also displaying the internal structure made by animal as it moved its burrow up or down, depending on whether it had sediment dumped on top of its burrow (move up!) or the top was eroded (move down!). I think this one went down, but can’t say for sure without seeing the burrow bottom, which is not preserved here. (Photo by Anthony Martin.)

Chondrities-CincinnatianThis branching burrow, which if reconstructed in three dimensions would look like an upside-down bush, was made by an animal (or several with their burrows overlapping) feeding on the sediment. The branches are from repeated probing into the surrounding sediment, then withdrawing, then probing again. (Photo by Anthony Martin.)

Dry-Dredgers-1What other trace fossils are in these outcrops of Ordovician limestones and shales? Too many for these people to see them all and study, but clearly they don’t care. And that’s a good thing. (Photo by Anthony Martin.)

Rooted in Time

As a paleontologist and geologist, time is always on my mind. Nonetheless, such musings do not always connect with millions or billions of years, the so-called “deep time” that earth scientists love to use whenever shocking people who normally ponder shorter time intervals used when, say, measuring the life of a fruit fly, or the length of a cat-themed video.

Still, sometimes other paleontologists and I also try to interpret brief time spans, such as a few minutes, hours, or years, but ones that elapsed millions of years ago. This is where ichnology comes in handy as a tool, as animal traces in particular – such as tracks or burrows – can give “snapshots” of animal behavior in the context of their original ecosystems. For instance, when I look at a limestone layer that was first laid down 95 million years ago and see burrows in that limestone, I think of it as soft, carbonate-laden mud with many small crustaceans digging into it. This is an instance of where imagination becomes a time machine, helping us to create evidence-based explanations that hopefully can be later honed with further scrutiny and re-imagining. When trace fossils are preserved as an assemblage in the sediments of that past ecosystem, whether it was a soil, lake bottom, or beach, the stories can be told in chronological order.

Throw plants into the mix, though, and they can screw up those linear-time stories to the point where you doubt every earth scientist when they tell a story about an ancient land-based ecosystem. Plants can occupy sediments that are hundreds, thousands, or millions of years old, and if their roots penetrate deep enough into these sediments, they may leave both remnants of their tissues and root traces. These geologically fresh root traces then mix with older animal trace fossils, conjuring the illusion of a contemporaneous community, all living happily together. Only a careful examination of the sediment, and which traces cut across which, would help to unravel the real story.

In the preceding video – taken more than four years ago on Sapelo Island on the Georgia coast – I tell such a cautionary tale of what happens when you assume that the animal and plant traces in an old sediment were made at the same time. (Spoiler alert: You would be wrong.)

For more about this relict marsh and the fascinating lessons we can learn from it, please read Fossils In Progress (which includes a short bibliography) and Teaching on an Old Friend, Sapelo Island. Both posts also discuss how to teach students some of these concepts of interpreting fossilization, paleoecology, and geologic time when in the field.

Ichnology in the Beer Garden of Good and Evil

For reasons unfathomable – but ultimately forgivable – I had never talked about my 2013 book Life Traces of the Georgia Coast in the lovely and historic city of Savannah, Georgia. There were many reasons for me to go there, preach the gospel of traces, and otherwise enlighten its citizens about the Holy Trinity of Ichnology (Substrate, Anatomy, and Behavior – amen, brothers and sisters!). For one, Savannah is not only the largest city in Georgia along its coast, but also has inspired many writers as a place. Even better, a good number of people there are keenly interested in the nearby ecosystems and non-human life inhabiting the Georgia coast. So it made sense to visit  and plug my book, which, despite having been out for more than a year, was regrettably unknown to most people in Savannah. Yeah, I know, some other book got in the way during the past year, but still.

Beer-Science-Sign-Anthony-Martin-Moon-RiverWho could resist the winning combination of science and beer? Here’s the sign we put out at Moon River Brewing Company in Savannah, Georgia as a siren call to those who might have wandered by. Lettering by Savannah artist Betsy Cain and trace fossil icons (theropod track on the left and a U-shaped burrow on the right) by me. (This photograph and all but the last were taken by Ruth Schowalter.)

With the help of well-connected friends there (who I hereby dub The Hartzell Power Couple™), we arranged for a book-related event in Savannah at a downtown microbrewery – Moon River Brewing Company – and placed it in their new outdoor beer garden. (Sorry bookstores, museums, and universities, you just can’t compete with that.) A local independent bookstore, The Book Lady Bookstore, helped out by selling my more recent (and much more reasonably priced) dinosaurian-themed book. But I also brought copies of Life Traces of the Georgia Coast for anyone interested in getting it for a bargain  from the author. Major bonus: all conventional author traces in these books (otherwise known as “autographs”) are always accompanied by my original drawing of a trace.

Geologists-Having-Beer-Science-BooksChatting with the locals, including (left to right), environmental activist Ann Hartzell, my two most recent books, me, and an anonymous geologist (right) who stopped by to talk about geology and paleontology. How can you tell he’s a geologist? Note the voluminous but mostly empty stein just behind him.

Advance publicity for the event was excellent, too, exceeding the expectations of most authors who wistfully hope that more than five people hear about their book-related event. For instance, Leslie Moses, a reporter for the local newspaper (the Savannah Morning News) wrote an article about my book, which included a nice photo of me standing (appropriately enough) on the Georgia coast. A reporter for the free weekly paper (Savannah Connect), Jessica Leigh Lobos, also conducted a delightful interview with me, in which I got to connect (get it?) both Life Traces of the Georgia Coast and Dinosaurs Without Bones via their common theme of ichnology enriching our otherwise mundane lives. Yet another reporter, Mary Landers (again for the Savannah Morning News) wrote a fun announcement about the event in which she alluded to my recent blog post about Godzilla’s tracemaking abilities. So let’s just say I felt loved by the local media, and the Hartzell Power Couple™ were able to bring in lots of their environmental-artistic-cool friends to attend the event, too.

Beer-Science-Sign-Moon-River-Betsy-CainSavannah environmental artist Betsy Cain graciously offered her calligraphy skills for the sign advertising the event, to which I later added my artistic depictions of trace fossils (see the photo at top for our finished masterpiece). In the background, The Hartzell Power Couple™ set up the much-needed-and-appreciated sound system I later used to project ichnological bon mots.

My talk at the beer garden wasn’t the usual formal slide show (i.e., Death by Powerpoint) we academics are expected to give almost by reflex nowadays. Instead, it was a totally different format adapted to the given circumstances. A lack of screen and projector, along with the outdoor setting and a nearby busy (and loud) city street, ensured that this would not be like any other talk I’d given about either book. Fortunately, at the urging of my ever-so-wise wife Ruth and the amazing resourcefulness of The Hartzell Power Couple™, I was able to get a microphone and speaker to speak over the urban din. But what to say, and how to say it without the support of pictures and oh-so-mesmerizing-and-persuasive bullet points?

Moon-River-Beer-Garden-ScienceA good example of how science education is wherever you take it: Thursday evening at the Moon River Brewing Company beer garden in Savannah, Georgia.

Thus I decided to make this book presentation more of a lively piece of performance science, rather than a lecture. It was part informative – with “elevator speeches” about each book on why they mattered, punctuated by brief (less than two minutes) readings – and part interactive. The latter was mostly improv, in which I asked audience members to shout out the name of their favorite Georgia-coast animal, followed by my acting out that animal’s tracemaking behavior, then describing what traces they would make from such behaviors. Alligator! Ghost crab! Sandhill crane! Fiddler crab!

Behold-My-Mighty-Claw-Fiddler-Crab-Dance“Look at my claw!” There’s nothing like a good fiddler-crab dance to warm up a crowd.

Preaching-Church-Ichnology-Moon-River-2Science authors, if you’re going to talk about your book in public, always make sure you have one as a prop so you can hold it up and say, “Have you heard the good news?”

Babies-Dig-IchnologyBabies dig ichnology.

Based on feedback from those there and my own perceptions of audience reactions, I thought the event went great. Not only did I have a good time, we even sold a few books. But something else that happened, and it was something that advocates of public-science outreach might note. I witnessed a subtle transformation in the people who were there at the beer garden just to have dinner, chat, and drink beer (and not necessarily in that order). First they ignored the “show” going on beside them, but soon they ended up listening, getting interested, and next thing you knew, they were (gasp) learning science.

Future-Paleontologist-Reading-BooksAfterwards, two science enthusiasts (mother and son) check out my books. One of those books went home with them, and may have later contributed to even more sciency goodness.

Ultimately, I hope my example introduced the Savannah community to the concept of a science tavern, which has been fantastically successful in Atlanta and is being adopted in several other U.S. cities. A key component of the Atlanta Science Tavern’s success, though, is making sure scientists are on board with being clear, lively, original, and fun with their science. As much as this paleontologist hates to admit, beer can only take you so far.

Goldfinch-Foot-Martin-Moon-RiverSomehow a copy of Donna Tartt’s The Goldfinch ended up in the same box holding copies of my book Dinosaurs Without Bones. Seizing a teaching moment, I explain with my hand how this literary juxtaposition was completely appropriate, because goldfinches are dinosaurs, and their feet (and hence their tracks) show this ancestor-descendant relationship.

So for all of you science authors out there who love public outreach about the science and the beer you love, please flatter me through imitation and try this on for yourself, then let the rest of the world know how it went. Think of it as an experiment that requires much repeating. If it doesn’t work, don’t do it again. If it mostly works, then revise it based on suggestions by your peers (the audience, that is). It it works fantastically, do that again. Repeat until science is shared and beer mugs run dry. Good luck!

Hartzell-Power-Couple-Ruth-TonyMany thanks to: Ann and Andrew Hartzell (left) for hosting Ruth and me (right) during our fun time in Savannah; Ruth for all of her expert photographic documentation and loving support; Joni Saxon-Giusti and Chris of The Book Lady Bookstore; Brandi Cockram of the Moon River Brewing Company; Savannah reporters Jessica Leigh Lobos, Leslie Moss, and Mary Landers; Betsy Cain; Robin Gunn; Sarah Ross; Craig Barrow; and all of those folks in the beer garden who didn’t expect to get some science on a Thursday night out in Savannah. Hope it happens again to you soon.

Cumberland Island, Georgia: Not a Barrier to Education

When learning about the natural sciences, there comes a time when just reading and talking about your topics in the confines of a classroom just doesn’t cut it. This semester, we had reached that point in a class I’m teaching at Emory University (Barrier Islands), in which we all needed a serious reality check to boost our learning. So how about a week-long field trip, and to some of the most scientifically famous of all barrier islands, which are on the coast of Georgia?

Last Friday, March 8, our excursion officially began with a long drive from the Emory campus in Atlanta, Georgia to St. Marys, Georgia. Fortunately, Saturday morning was much easier, only requiring that we walk across the street, step onto a ferry, and ride for 45 minutes to Cumberland Island. Cumberland was our first island of the trip, and the southernmost of the Georgia barrier islands. I have written about other topics there, including the feral horses that leave their mark on island ecosystems, the tracks of wild turkeys, and those marvelous little bivalves, coquina clams.

So rather than my usual loquacious ramblings, punctuated by whimsical asides, this blog post and others later this week will be more photo-centered and accompanied by mercifully brief captions. This approach is not only a practical necessity for proper time management while teaching full-time through the week, but also is meant to give a sense of the daily discoveries that can happen through place-based learning on the Georgia coast. I hope you learn with us, however vicariously.

After a 45-minute ferry ride to Cumberland Island, the students received a different sort of lecture when naturalist extraordinaire Carol Ruckdeschel – who is writing a book about the natural history of Cumberland Island – met with them and gave them a brilliant overview of the island ecology. She mostly talked with the students about the effects of feral animals on the island, then spent another hour with us in the maritime forest and through the back-dune meadows. It was a real treat for the students and me, and a great way to start the field trip.

A leaf-cutter bee trace! Despite my writing about these and illustrating them in my book, these distinctive incisions were the first I can recall seeing on the Georgia barrier islands. These traces were abundantly represented in the leaves of a red bay tree we spotted along a trail through the maritime forest, making for a great impromptu natural history lesson for the students.

A freshly erupted ghost shrimp burrow on the beach at Cumberland, in which the students were lucky enough to witness the forceful ejection of muddy fecal pellets by the shrimp from the top of its burrow. I mean, really: explain to me how the life of an ichnologist-educator can get any better than that?

The fine tradition a field lunch, made even more fine by the addition of fine quart sand to our meals, freely delivered by a brisk sea breeze. Did the sand leave any microwear marks on our teeth? I certainly hope so.

A student is delighted to test my ichnologically based method for finding buried whelks underneath beach sands, and find out that it is indeed correct. (Was there any doubt?) Here she is proudly holding a live knobbed whelk, which I can assure you she promptly placed back into the water once its photo shoot was finished for the day.

Just to join in the fun, other students decided my “buried whelk prospecting” method required further testing. Let’s just say this student did not disprove the hypothesis, but rather seemed to confirm it, and doubly so. It’s almost as if ichnology is a real science! (Yes, these whelks went back into the water, too.)

OK, enough about marine predatory gastropods (for now). How about some of the largest horseshoe crabs (limulids) in the world? We found a large deposit of their carapaces above the high-tide mark, some of which were probably molts, but others recently dead. Sadly, though, we did not see any of their traces. Bodies only do so much for me.

Where do dunes come from? Well, a mother and father dune love each other very much… No wait, wrong story. What happens is that dead cordgrass from the salt marshes washes up onto the beach, where it starts slowing down wind-blown sand enough that it accumulates. Now it just needs some wind-blown seeds of sea oats and other plants to start colonizing it, and next thing you know, dune. Dude.

Ah, a geological tradition in action: comparing actual sand from a real outdoor environment to the sand categories on a handy grain-size chart, and using a hand lens. It’s enough to bring a tear to the eyes of this geo-educator. Or maybe that was just the wind-blown sand.

Finally, something that really matters, like ichnology! This is a three-for-one special, too: sanderling feces (left), tracks, and regurgitants (right), the last of these also known as cough pellets. Looks like it had coquina and dwarf surf clams for breakfast.

Wow, more shorebird traces! The tracks are from a loafing royal tern, and it clearly needed to get a load off its mind before moving on with the rest of its day.

Tired of shorebird traces? How about a modern terrestrial theropod? Wild turkey tracks in the back-dune meadows of Cumberland were a happy find, leading to my grilling the students with the seemingly simple question, “What bird made this?” They did not do well on this, but hey, it was the first day, and at least no one said “robin” or “ostrich.”

Did somebody say “doodlebug?” This long, meandering, and collapsed tunnel of an ant lion (a larval neuropteran, or lacwing) tells us that this insect was looking for prey in all the wrong places.

Behold, tracks that bespeak of great, thundering herds of sand-fiddler crabs that used to roam the sand flats above the salt marsh. Where have they gone, and will they ever come back? Who knows where the males might be waving their mighty claws? Do the female fiddler crabs suffer from big-claw envy, or are they enlightened enough to reject cheliped-based hierarchies imposed upon them by fiddler-crab society? All good questions, deserving answers, none of which make any sense.

Yes, that’s right, feral horses are really bad for salt marshes. Between overgrazing and trampling, they aren’t exactly what anyone could call “eco-friendly.” My students had heard me say this repeatedly throughout the semester, and Carol Ruckdeschel said the same thing earlier in the day. But then there’s seeing it for themselves, another type of learning altogether.

And the day ended with beautiful ripple marks, beckoning from the sandflat below the boardwalk on our trip back onto the ferry. Even this ichnologist can appreciate the aesthetic appeal of gorgeous physical sedimentary structures.

What’s the next island? Jekyll, which is just north of Cumberland along the Georgia coast, visited yesterday. Stay tuned, and look for those photos soon.

Using Traces to Teach about Traces

This past weekend, my colleague Steve Henderson and I co-led a field trip to Sapelo Island, Georgia with 13 Emory University undergraduate students and our spouses. This trip is done biannually as a firm requirement for students taking a class of mine at Emory called Modern and Ancient Tropical Environments. This course, in turn, is a prerequisite for a 10-day field course we’ll do in December-January, ENVS 242, which appropriately has the same name as ENVS 241 except for the addition of “Field Course” at the end. That course, though, will take place on another island, albeit a very different one, San Salvador, one of the “Out Islands” of the Bahamas.

Why were we on Sapelo Island to prepare for a field course in the Bahamas? It was to fulfill several learning goals that will sound familiar to all science educators who take their students outside of a classroom for their learning. In no particular order, these are:

  • Get students to observe natural phenomena while in the field;
  • Ask good questions about what they’ve observed;
  • Learn how to properly record their observations;
  • Come up with explanations (hypotheses) for whatever questions were provoked by their field experiences; and
  • Staying safe while doing all of this, which included adjusting to whatever conditions we might encounter in the field.

Our spouses, Ruth Schowalter and Kitty Henderson, are also educators; Ruth teaches English as a Second Language (ESL) at Georgia Tech, and Kitty is a middle-school earth-science teacher in Covington, Georgia. Moreover, both have been to Sapelo Island many times, having gained a wealth of field-gained knowledge about its natural history. Hence our students were lucky to have all four of us there to introduce them to the island, and we likewise felt very fortunate to be there with such an eager group on a gorgeous fall weekend.

Environmental Studies students from Emory Univeristy with me (foreground) and Steve Henderson (right), looking at a 500-year-old relict salt marsh, exposed by erosion along Cabretta Beach on Sapelo Island, Georgia. Sure beats staying in a classroom to learn about modern and ancient environments. (Photograph by Ruth Schowalter.)

Of course, once on Sapelo or any other barrier island of the Georgia coast, I cannot help but use ichnology – the study of traces – as a uniting theme for my teaching. Steve, who did his Ph.D. research on Sapelo in the late 1970s, is more of a taphonomist, which is someone who studies how fossils are made, from death to burial to preservation. Nonetheless, ichnology and taphonomy overlap considerably, hence our respective approaches complement one another very well, a synergism aided by our having had the same Ph.D. advisor – Robert (Bob) Frey – at the University of Georgia. Once in the field, every track, burrow, feces, and body part of a dead animal we found – and the occasionally sighted live animal – became a dynamic learning opportunity for us, in which we could apply basic scientific methods that were all accented by a sense of wonder.

A dead blue crab (Callinectes sapidus) found in the middle of Sapelo Island, at least 2 kilometers (1.2 miles) from the ocean. How did it get there, and what happened to it? Our students went through the possibilities based on the evidence – main body nearly entire, no toothmarks on it, but bleached white and missing most legs. We finally concluded that it had been dropped by a large predatory bird, such as a great blue heron (Ardea herodias) or great egret (Ardea alba), which probably had shaken off most of the crab’s legs before attempting to eat it. A nice little lesson in taphonomy, for sure. (Photograph by Anthony Martin.)

But perhaps my favorite teaching techniques to use while on Sapelo or any other Georgia barrier island is to use the completely low-tech and ancient method of drawing in the sand. Through my own traces, then, I can teach my students about ichnology and its applications to understanding geologic processes. For example, one of the beaches on Sapelo – Cabretta Beach – is undergoing rapid erosion from a combination of longshore drift and sea-level rise. At this place, downed pines and oaks laid prone in the surf, a former forest now a beach. This was the perfect place to introduce the students to Walther’s Law, which states that laterally adjacent environments will succeed one another vertically in the geologic record. This principle then can be applied to figuring out how a given sequence of strata might reflect a rising or lowering of sea level in the past.

No PowerPoint? No projector? No computer? No problem. Teaching in the field is easy when you have such a nice canvas to work with. (Photograph by Ruth Schowalter.)

So with the sea behind me, a sandy beach wiped clean by the receding tide, and a handy stick, I scratched out a typical sequence of sedimentary strata and their diagnostic traces that would result from sea level going up (a transgression) on the Georgia coast. (Ruth and I were also inspired to create artwork on this theme, discussed in a previous entry.) Terrestrial environments with tree-root and insect traces were at the base of the sequence, succeeded vertically by sandy dune deposits with ghost-crab and insect burrows, then sandy beach deposits with ghost-shrimp burrows, topped off by offshore sandy muds and sands burrowed by fully marine echinoderms, such as heart urchins, sea stars, and brittle stars. I then asked the students to look around them and point to each of the laterally adjacent environments represented in my sand drawing, which they dutifully did. Finally, just to make sure our students got it, we inquired about what sequence should result if sea level dropped, and they correctly surmised that the place would revert back to terrestrial conditions, with the marine sediments buried below.

My applying the final touches on a sand-sketch masterpiece of a transgressive-regressive sequence of strata and its traces, as my students watch. Would you like to see it? Sorry, the tide came in just a few hours after I drew it, and we didn’t get a photo of it. So you’ll just have to draw your own, and preferably on a beautiful beach. (Photograph by Ruth Schowalter.)

As we all stood back to look at the transgressive-regressive sequence of strata, the formerly abstract concept of Walther’s Law became far more real for our students. The dead trees on either side of our group, an eroded dune and maritime forest behind us, and the sea in front of us, all reinforced this lesson, bolstered by our presence in a place with those environments being actively affected by geological and biological processes.

Another instance of using traces in the sand to teach about traces was with ghost-shrimp burrows. At low tide on the previous day of the field trip, the students found many small, volcano-like mounds on the intertidal beach surface some with neat piles of tiny mud-filled cylinders that looked like “chocolate sprinkles” sometimes seen on cupcakes. What were these?

I informed them that we were looking at the tops of ghost-shrimp burrows and their fecal pellets; earlier, we had seen the knobby, pelleted walls of these same ghost-shrimp burrows, which were the deeper parts. What does an entire ghost-shrimp burrow system look like in cross-section? Time for another sand drawing. This one introduced the students to what had been only disembodied words memorized for an exam – ghost shrimp, pellets, walls, vertical shafts, branching – that now could be supplemented by actual traces next to the drawing. You can’t beat these sorts of visual aids, a huge bonus from our being in the right places to see them.

Using a “clean slate” of a beach wiped smooth by the tide for sketching a cross-section of a typical ghost-shrimp burrow, many of which also happened to be underneath our feet. (Photograph by Ruth Schowalter.)

The final sketch of a ghost-shrimp burrow, showing its volcano-like top, narrow “chimney” leading down to the main shaft of the shrimp’s living chamber, some of the pellets lining its burrow walls, and the geometry of the burrow network below. (Photograph by Anthony Martin.)

Was my teaching technique new and innovative, worth presenting at an educational conference as an assessment-friendly pedagogy that would maximize outcome-based education? In short, no. Sand drawing as a tool for education has a very long tradition in indigenous cultures, especially those that have their own forms of ichnology (such as tracking) at their cores. For example, in central Australia, Ruth and I had seen a creation story etched in the ground that had been done some by the Arrente people who live near Uluru. This story likewise used animal traces (emu tracks) as a key feature, a sort of iterative use of traces for inspiration and teaching.

Creation story of the Arrente people drawn in the soil near Uluru in Northern Territory, Australia. The figure at the bottom is an emu, and its tracks are shown leading away from it. (Photograph by Anthony Martin.)

At the same place, we also watched an Arrente elder demonstrate how to make animal tracks using only his fingers and palms, which was also described in books we had read about

Did you know you can use your hands to make animal tracks? In this photo, I use the fine-grained dune sands of Sapelo Island to create a reasonable depiction of kangaroo tracks. Yes, I know, kangaroo tracks on the Georgia barrier islands are not very likely, but you get the idea. Next time I’ll do raccoon tracks instead.

Some of us educators are old enough to remember using a technological succession of blackboards and chalk, overhead projectors with pens, whiteboards with dry-erase pens, and now presentation software (Keynote, PowerPoint, and so on) for imparting lessons. So it gives me great comfort to know that, with a generation of students who have never known a world without computers with a concomitantly reduced connection to the outdoors, we can still switch back to using the ground beneath our feet, our eyes, hands, and imaginations to teach and learn about the life traces around us.

Further Reading

Bingham, J. 2005. Aboriginal Art and Culture. Raintree, Chicago, Illinois: 57 p.

Hoyt, J.H., and Hails, J.R. 1967. Pleistocene shoreline sediments in coastal Georgia: deposition and modification. Science, 155: 1541-1543.

Hoyt, J.H., Weimer, R.J., and Henry, V.J., Jr. 1964. Late Pleistocene and recent sedimentation on the central Georgia coast, U.S.A. In van Straaten, L.M.J.U. (editor), Deltaic and Shallow Marine Deposits, Developments in Sedimentology I. Elsevier, Amsterdam: 170-176.

Louv, R. 2005. Last Child in the Woods: Saving Our Children from Nature-Deficit Disorder. Algonquin Books, Chapel Hill, North Carolina: 390 p.

Middleton, G.V. 1973. Johannes Walther’s Law of the Correlation of Facies. GSA Bulletin, 84: 979-988.

Weimer, R.J., and Hoyt, J.H. 1964. Burrows of Callianassa major Say, geologic indicators of littoral and shallow neritic environments. Journal of Paleontology, 38: 761-767.