Ghostly Traces of Ancient Behemoths

A recent article in the New York Times described challenges facing the Iraq Museum. Heavily looted in 2003 during the US invasion, it reopened in 2015 with a considerable collection, yet still struggles with public engagement. Not surprising, as there appear to be few resources to help visitors, such as audiovisual aids or docents. But what struck me most were the words of Iraq’s Cultural Minister, Abdulameer al-Hamdani, who said, referencing the artifacts in display cases, “In a box, art has no soul.”  His statement revolved around context: if you don’t understand what you’re looking at, its impact may not be as powerful.  As NY Times journalist, Alissa Rubin, explained, “Great works like the three-foot-tall Warka vase…are arresting sights but much more so when their history is explained.”

This resonates strongly for me when thinking of paleontology.

It’s easy to be impressed with larger fossils, articulated skeletons displayed in life-like poses. Regardless of one’s level of interest or knowledge, we can appreciate a mounted Triceratops. We know what that is. When you learn about the research done within the bones, however, and discover how scientists are learning about growth rates, blood vessel volume, what that blood vessel volume means for the way that dinosaur looked, whether areas of the body were covered in keratin or scales, that mounted skeleton takes on an entirely new meaning.  It becomes fleshed out in our mental images.  It goes from, “yes, that is an impressive fossil” to “WOW.  What an incredible animal!”  And, consequently, we have more connection to it.

That connection, to me, is the “soul” referenced by Mr. al-Hamdani. The details an ordinary person wouldn’t see when looking at fossils are the very things that bring that extinct species back to life.

 

Image of ‘Cliff,’ the Triceratops fossil at the Boston Museum of Science, photo taken by Jeanne Timmons. (‘Cliff’ might imply we know the sex of this animal; we do not. I don’t believe this was named by museum staff.)

 

When a friend of mine mentioned an upcoming trip to White Sands National Monument, it was with a sense of excitement, and I was happy for him.  White Sands was a name I recognized. It was, after all, the site of an incredible discovery unveiled last year: Giant Ground Sloth fossil footprints interacting with fossil hominid footprints. Evidence that humans may have been stalking that sloth, perhaps hunting it or, as Ed Yong at The Atlantic suggested in his piece about the discovery, maybe toying with it. Whatever their intent, hominids were doing something that repeatedly caused the sloth to turn abruptly and leave prints suggesting defensive movement.  

Paleoart of the possible interaction between a Giant Ground Sloth and ancient hominids, as depicted by Alex McClelland from Bournemouth University

 

That research put the National Monument on the map for many of us. I’d read the research and the articles about it.  I had a general idea of what was there.  “Footprints preserve terminal Pleistocene hunt? Human-sloth interactions in North America” (the 2018 paper of that discovery) mentioned that sloth and hominid footprints are only two of several species that left tracks so long ago in what is now New Mexico.  Preserved tracks remain of camelids, canids, bovids, felids, and proboscideans (most likely Columbian mammoths, although mastodons are possible, too).

So I understood my friend’s excitement, and I shared it to the degree of what little I knew of White Sands at the time, but I think it’s fair to say our levels of excitement were distinctly different.

 

Image of fossil hominid footprint inside a fossil Giant Ground Sloth footprint, photo courtesy of David Bustos, White Sands National Monument, New Mexico

 

 

Then I connected with scientists actively researching there.  Dr. Sally Reynolds, Dr. Matthew Bennett and David Bustos are three of the co-authors on the aforementioned paper, and they are among the authors of yet another paper on White Sands to be published in this August’s edition of Palaeogeography, Palaeoclimatology, Palaeoecology.

“Soft-sediment deformation below mammoth tracks at White Sands National Monument (New Mexico) with implications for biomechanical inferences from tracks” offers detailed insight into mammoth footprints and how they impacted the ground upon which they walked. To do so, the scientists analyzed the rock below the tracks themselves.

This study is arguably an asset to ichnologists, those who specialize in fossil traces such as bite marks, scratches, footprints and more. It provides richly detailed graphics and descriptions of how the mammoths’ foot pressures affected the sediment. Because hominid tracks intersect and even step into mammoth tracks, these footprints are analyzed as well.

Admittedly, this information might not be first choice among those who aren’t ichnologists, but I guarantee you their interpretation of this information might be.

Understanding what these footprints reveal is like opening a window into a moment of that animal’s life.  It can tell us about the possible weight and size of the animal who made them; the stride of that animal; whether it was walking, limping or running; whether it was alone or not; and it tell us about the environment in which it walked.  These are clues into the behavior of the animal, an entire realm beyond its physical make-up.

 

 

Screenshot of mammoth footprint analysis (deformation structures) at White Sands by Bennett et al, “Soft-sediment deformation below mammoth tracks at White Sands National Monument (New Mexico) with implications for biomechanical inferences from tracks” 

 

 

This is exactly what interests Dr. Sally Reynolds, Senior Lecturer in Hominin Palaeoecology and Deputy Head of the Institute for Studies of Landscape and Human Evolution (ISLHE) at Bournemouth University.

“I’m interested in the footprint in the behavioural context,” she wrote in an email. “What do the footprints tell us about the snapshot of activity taking place?”

“I like to think in terms of how these people used their landscape,” she continued, referencing her work understanding the paleoecology of an area and how that impacted ancient hominids. “I ask myself and the team questions like:

1. Where was the water? Were they waiting by the water to ambush the prey animals?
2. What were they eating? Plants, insects, animal prey?
3. What sort of technologies did they have for collecting these? Evidence of hunting, but also gathering, trapping etc.
4. What sort of toolkits did they have to use? Stone tools, fire etc.
5. What were they afraid of? Predators, poisonous snakes, etc. These animals are still largely resident in the region today. There is much recent ethnographic and ecosystem evidence that can be considered when reconstructing the ancient worlds of these people.
6. Group size? Gender roles, presence of children, roles of children.”

While he focuses more on ichnology, that sentiment is echoed by Dr. Matthew Bennett, Professor of Environmental and Geographical Sciences, also at Bournemouth University.

“I am now more interested in behavioural ecology derived from footprints – basically how one animal (human or not) interacts with another,” he wrote. “This for me is where the excitement and new research frontier is.”

 

Fossil hominid footprint within a fossil mammoth footprint at White Sands, photo courtesy of David Bustos

 

Both scientists have published on fossil hominids–footprints and bones–and associated ichnofossils of other species for years. Their collective expertise lends crucial understanding to an area in which there are not just a few footprints here and there, but thousands upon thousands.

More importantly, these footprints—in some cases—go on extensively.

“Some of [the trackways] go for half a mile or a mile. We have a camel track that [is] almost two miles,” David Bustos, Resource Manager for White Sands explained by phone.  “Because these prints are so long, they allow you to see interactions that you wouldn’t see at other places. They’re so unique. There are prints all over the world, but to have prints that extend for such a long distance and keep interacting with other animals or people is very unique.”

I want to reiterate that point, because this is where my enthusiasm for White Sands became almost palpable: the tracks at that site are not only profuse, they can be followed over 1-2 miles.  If relatively short trackways have provided great insight into extinct behavior, these tracks offer potentially unparalleled revelations.

“[T]he thing about it is,” he continued, referencing the sloth and hominid trackways described in the 2018 paper, “it’s not the only occurrence.  This is happening over and over across Monument lands.”

 

Screenshot of fig. S3. from Supplementary Materials for “Footprints preserve terminal Pleistocene hunt? Human-sloth interactions in North America”

fig. S3. Map of part of the study site. The map shows sloth and human tracks as well as track density across the whole site (inset). Note the non-linear sloth trackways and sudden changes of direction. “Flailing circles” occur only in association with human tracks.

 

“We see human, mammoth, Giant Ground Sloth, and camel prints commonly together across the monument. Occasionally you’ll see bison and occasionally you’ll see dire wolf or American lion or some type of felid.”

“The proboscidean prints we have are amazing. We have thousands of these prints at the monument. (They are probably the most numerous track type we have.) In the tracks, you can see young and old animals.  Some places you can see the prints of the young running in circles and then nudging up against the larger animals perhaps to say ‘hello’ or [to] nurse.“

A fossil Giant Ground Sloth trackway at White Sands, photo courtesy of David Bustos.

 

But there’s a twist: seeing some of the tracks depends upon just the right environmental conditions.

As David explains, “You’ll walk by the same area for years, [and] then the conditions will change. There is now a fine salt crust on the surface, and in the crust you’ll find a whole new set of prints, only to be gone the next day. These are the trackways that we call ghost prints.”

“[We saw] thousands of new prints we’ve never seen before,” he said, illustrating just one example. “And they were gone two or three days later. You couldn’t see them anymore. [S]omething changed with the soil that didn’t leave a fine salt crust over everything.”

Alarmed, I asked him if this meant they were gone for good.  He assured me that, “They’re still there, so if we were to look for them with GPR [ground-penetrating radar] or scrape back the soil, they would be there. But they’re not visible to the naked eye. You can’t see them.”

Ghost tracks (or “ghost prints”) aside, there is another, more ominous threat to the trackways: erosion.  This has lead David Bustos and his team at White Sands to work diligently to preserve as much as they as quickly as they can.  They are a small operation.  They’ve looked to outside groups and experts to help understand the fossils, see the value of the site, get the word out and help save the footprints.  To that end, they have actually excavated tracks.

“[The footprints] that we have brushed open [are] a small sample of [specific trackways],” David expressed. “There might be 2-3,000 prints, and, of those, we might open up 15 prints or so.  [The reason we excavate them at all is to get a better] understanding of the different types of prints, how they differ from each other (are toes visible,  how deep are the prints, how did they walk, were they slipping in the mud), and to get [good] measurements for the gait and stride and pace and all of those types of things. After the measurements are taken and prints documented, the prints are filled in.”

 

Images of the various types of proboscidean footprints found at White Sands: what they look like above ground and then images of what they look like underground; photos and graphics from the National Park Service.

 

 

Despite their hard work, it is not always enough.

“We were seeing places where we know we’ve lost large-scale sets of prints and tracks from soil erosion,” he stated.

David compared the loss of those prints to a significant loss of books from the Library of Congress.  Losing those fossils is like losing an enormous “volume of data.”

“[T]hey’re incredible in the stories that they tell you,” he said.  “A mother carrying a child. Or an old person limping along w/a larger group. Or maybe a younger person sprinting along the larger group (deep prints that are nearly three times the length of a walking stride). You see people interacting with each other.  And you see people interacting with the megafauna.”

Still, he is hopeful.

“It’s been an amazing project and we’ve had a lot of great support from everyone who helped us to get where we are.”

“It seems like every year there’s more and more  discoveries.  We’ve looked at maybe less than 1% of 51,000 acres that could contain trackways.”

The published research done by David, Sally, Matthew and their co-authors is far from finished.  Offering me tantalizing clues, I would encourage everyone to keep an eye out for what comes next.

As far as the secrets revealed by White Sands National Monument, this is only the beginning.

Partial screenshot of an image from “Soft-sediment deformation below mammoth tracks at White Sands National Monument (New Mexico) with implications for biomechanical inferences from tracks” that illustrates where in White Sands the research was done and the megafauna that left footprints

 

*****

There is currently a Senate bill to make White Sands National Monument a National Park!!

More info here: https://www.govtrack.us/congress/bills/116/s1582/text/

Dr. Matthew Bennett has freeware that, as he describes it, “allows you to capture tracks digitally using photogrammetry (20-40 oblique photos with a digital camera), but crucially it provides you with a series of tools to analysis and compare those tracks. Unlike many 3D programmes that have to cater for lots of users with different requirements, this is purely for footprints.”

Find out more here: DigTrace, http://www.digtrace.co.uk

 

References:

1. Bennett, Matthew R., Bustos, David, Belvedere, Matteo, Martinez, Patrick, Reynolds, Sally C., Urban, Tommy; Soft-sediment deformation below mammoth tracks at White Sands National Monument (New Mexico) with implications for biomechanical inferences from tracks; Palaeogeography, Palaeoclimatology, Palaeoecology, 1 August 2019
2. Bustos, David,  Jakeway, Jackson, Urban, Tommy M., Holliday, Vance T., Fenerty, Brendan, Raichlen, David A., Budka, Marcin, Reynolds, Sally C., Allen, Bruce D., Love, David W., Santucci,  Vincent L., Odess, Daniel, Willey, Patric, McDonald,  H. Gregory,  Bennett, Matthew R.; Footprints preserve terminal Pleistocene hunt? Human-sloth interactions in North America; Science Advances, 25 April 2018
3. Bustos, David, Much More than a Sand Box: Fossil Tracks from the Lakes of the World’s Largest Gypsum Dune Field, Park Paleontology News – Vol. 09, No. 2, Fall 2017
4. Bustos, David, National Park Service, Lake Lucero Ranger Minute, YouTube, Nov 21, 2016
5. Bustos, David, Love, David W., Allen, Bruce D., Santucci, Vincent L., Knapp, Jonathan P.; Diverse Array of Soft-Sediment Fossil Vertebrate Tracks from the World’s Largest Gypsum Dune Field, GSA Annual Meeting, Denver, 2016
6. Martin, Anthony J., Dinosaurs Without Bones, Pegasus Books, 2014
7. National Park Service, White Sands National Monument, The Pleistocene Trackways of White Sands National Monument, 2013
8. Rubin, Alissa J., In Iraq Museum, There Are Things ‘That Are Nowhere Else in the World‘, NY Times, June 9, 2019
9. Yong, Ed, Fossilized Human Footprint Found Nestled in a Giant Sloth Footprint, The Atlantic, April 25, 2018
10. White Sands National Monument, New Mexico, USA

 

What a great honor and a pleasure to connect with Sally Reynolds, Matthew Bennett and David Bustos!! Sincere thanks to all of you!!  Sally, your kind responses to my emails, your fascinating answers to my questions, and your constant support on Twitter have been great.  Matthew, thank you for your detailed responses at a time when you were incredibly busy.  David, thank you for responding to my emails and for making time to discuss my questions further by phone.  I wish all of you the best with your research, and I cannot wait to read what comes out next!!

This post would not have been possible without the thoughtfulness and help of my friend, Dick Mol.  Dick: You are a wonderful and generous person. THANK YOU. This post is dedicated to you and Friedje.

The Evolution Underground – Part 2: Behind the Scenes

“I still don’t understand why they were looking for alligator dens.”

My dad and I had been discussing the review I’d written about Dr. Anthony Martin’s latest book, “The Evolution Underground.”  He voiced this confusion with more concern for the overall safety (and perhaps sanity?) of the Emory professor and his students than an interest in what knowledge they hoped to gain.

To be fair, my dad hadn’t yet read this or any book about ichnology and was not familiar with the field.  My inability to make that part of the book clearer aside, it also spoke to a question I’d had this past December.  Speaking with him by phone, I asked Dr. Martin: Did he think more people know about ichnology as a result of his prolific work?

“I think,” he began thoughtfully, “through the books, [through] giving public talks, and [by blogging] about it, I’m fairly confident in saying, ‘yes, more people are more aware now of ichnology as a science.’ I think that ‘Dinosaurs Without Bones’ was a really good step [toward] popularizing ichnology as science, and then I think that ‘The Evolution Underground’ will take it another step further.”

Image of  Dr. Anthony Martin, courtesy of Emory University 

It is telling that, of the four books Dr. Martin has written so far, three of them focus on ichnology.  His handle on Twitter is @ichnologist.  Most of his blog posts feature concepts related to ichnology.  During our conversation, he chuckled and admitted he refers to himself as an “ichno-evangelist.”

Any physical remnant of an extinct or extant creature falls into ichnology: bites, scratches, footprints, marks indicating the drag of a tail, coprolites or scat.  Reading those traces—recognizing them for what they are—is a skill, and one for which there are relatively fewer reference points than the much older field of paleontology.*  Dr. Martin explains this in his first work with Pegasus Books, “Dinosaurs Without Bones.”  It is one thing to see a fossil femur, for example, and understand what it is.  Recognizing a fossil nest, however, or a fossil burrow, is considerably more challenging.  Without “search images” or reference points that help other scientists understand what to look for, such fossils might be easily missed.

Detail of a slab of fossil footprints surrounded with what are believed to be fossil raindrops at the Beneski Museum at Amherst College, Massachusetts. Both the footprints and the raindrops are examples of ichnology. Picture taken by the author of this blog.

 

Can you tell what these are? I can’t, and, so far, neither can the experts.  As-yet unknown trace fossils at the Beneski Museum at Amherst College, Massachusetts; pictures taken by the author of this blog.

Figure 1: A brief summary of animal burrowing through time, from the Ediacaran Period through today.  Geologic eras on left, periods on right, MYA = millions of years ago, and red arrows indicate times of mass extinctions in the geologic past. (Image and caption used with permission from Pegasus Books)

 

“Sage scents wafted by on the wind and, in between scoops, I looked around at the nearby pine forests and rolling, high-plains grassland nearly everywhere else, then up at an expansive blue sky hosting white, fluffy clouds.  You might say I was in a country where the sky was big: Some people just call it ‘Montana.’” – page 87, “The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet,” by Dr. Anthony J. Martin, Pegasus Books

In the book, Dr. Martin describes participating in an excavation in the Blackleaf Formation that lead to the discovery of the first known fossilized burrow, found collectively by Dr. Martin, Yoshi Katsura, and Dr. David Varricchio of Montana State University.

This discovery—based solely on noticing the odd structure of sediment surrounding bones—is no small feat.  Looking at an image of this burrow, which you can see in Dr. Martin’s blog post here, I am amazed that anyone would be able to decipher what it actually is when working through layers of other rock, let alone when it was completely revealed.

Dr. Martin credits his mentor and former professor, Bob Frey, with guiding him in ichnology.  Both Dr. Varricchio and Dr. Martin were fellow students in his class, a class that seems to have been a road map for both of them in their future discoveries.

And while in this book Dr. Martin discusses many extant burrowers, he certainly addresses those found in the fossil record as well.

Figure 38: Early Cretaceous (130 mya) lobster burrow preserved as natural cast on bottom of limestone bed, Portugal.  Although the lobster’s body is not preserved, its leg impressions and body outline were left behind.  (Photo by Anthony J. Martin; image and caption used with permission from Pegasus Books)

“The bigger picture behind these everyday observations of many holes in the ground, however, is that the long history of these burrowing invertebrates completely altered global environments, from the deepest sea to the highest mountains, and even affected the atmosphere and climate.  In short, the entire surface of our planet is built upon one big complex and constantly evolving burrow system, controlling the nature of our existence.” — page 14, “The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet,” by Dr. Anthony J. Martin, Pegasus Books

 

The quote above is the central theme of “The Evolution Underground.”  I wondered if he’d gained this perspective after completing the book, or if this was something he carried as he began writing.

“I did go in with that big picture idea about burrows having this overarching influence on all of our ecosystems,” he replied. “[That, we, too,] have this evolutionary heritage that [is] connected to burrows. So I did have that idea in mind, but it was really scattered. Really disparate.  Also, it wasn’t an original idea. Lots of other people really deserve credit for that, [and they are] cited in the endnotes of the book.

But, he said, “[w]riting the book definitely helped me pull together a lot of those previously separated ideas into the theme that I summarized as ‘burrows acting as the midwife in the birth of Gaia.’

“We can’t really talk about the evolution of ecosystems or the evolution of life without talking about burrows.”

Figure 16: Folk-art rendering inspired by the Lystrosaurus saga set during the Permian-Triassic transition (Chapter 5), with a cutaway view of a Lystrosaurus burrow. (Artwork by Ruth Schowalter and Anthony J. Martin; image and caption used with permission from Pegasus Books) — (The author of this blog wants to note, as Dr. Martin does in the endnotes, that his interest in the species was inspired by this piece by Annalee Newitz.)

Having written four books, did writing them get easier?

“It did get easier with each book,” he acknowledged. Then laughed. “But, of course, the word ‘easy’ is relative.”

“[‘The Life Traces of the Georgia Coast‘] was hard to write because it was so comprehensive.  It was almost 700 pages long; it had more than 800 peer-reviewed references. It’s an academic book, but I [also] wrote it for a popular audience.  So it’s a hybrid kind of book in that respect. That took four years from the acceptance of the book proposal to actually holding it in my hands.”

“And,” he added, “a book is not finished until I’m holding it in my hands.”

“In contrast to that, ‘Dinosaurs Without Bones’ was quick. That took me—from start to end—less than two years. I felt like [‘The Evolution Underground’] was a little bit easier than ‘Dinosaurs Without Bones,’ but that’s only because I used Pegasus Books again as the publisher. And I had the same editor: Jessica Case. With that said, it was still difficult to write because it covered so many different burrowing animals, [not to mention it covered] the last 560 million years!

“The main takeaway point of it is for people to better appreciate the world they don’t often see, and that’s the world below their feet. We might not even be here talking about burrowing animals if our earliest mammalian ancestors hadn’t burrowed.”

 

*This comment is not meant to hold one field over another. I have great respect for the skills needed for both paleontology and ichnology.

******

Thank you to Carol Clark, Senior Science Communicator at Emory University, for the wonderful picture of Dr. Martin!

A sincere and enthusiastic THANK YOU to Dr. Anthony Martin for his willingness to connect by phone and for his generous responses to my questions!  It was a pleasure and an honor to be able to speak with him, and—like his writing—he made it fun!  I eagerly (if impatiently) await any possible future work.  

FULL DISCLOSURE: The author of this blog loved Dr. Martin’s previous book with Pegasus, “Dinosaurs Without Bones,” and thus, jumped at the chance to review his latest work (fully predisposed to embrace it) by requesting a review copy from the publisher.  I am very grateful to Pegasus Books for the opportunity to do so. Being able to use such beautiful images from the book is a great honor! I am specifically grateful to Deputy Publisher, Jessica Case, with whom it was wonderful to work!!

******

References:

1. The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet, Anthony J. Martin, Pegasus Books, 2017
2. Dinosaurs Without Bones: Dinosaur Lives Revealed by Their Trace Fossils, Anthony J. Martin, Pegasus Books, 2014
3. Life Traces of the Georgia Coast Blog, Anthony J. Martin

The Evolution Underground – Part 1: Book Review

Not all scholars write with the playfulness or the open curiosity found in books written by Dr. Anthony Martin, professor at Emory University.

In his second work with Pegasus Books, “The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet,” he opens with an anecdote about an outdoor class on an island off of the Georgia coast.  If you have any question about whether this book is for you, read those first several pages.

He, his colleague, Michael Page, and several students were mapping alligator dens.  While they’d witnessed many active dens from a safe distance, in this instance, they were exploring those long abandoned by their former occupants.  They were, he explained to the reader, in the middle of the forest where a now-nonexistent canal once ran.  Without water, there would, of course, be no alligators.

Only he was wrong.  And this was pointed out when a student noticed teeth within the den.

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Picture of alligators by Michael Leggero, courtesy of Getty Images

You will need to read the book to find out what happens, but this first chapter perfectly encapsulates how Dr. Martin writes. If you want to learn about any aspect of our world from a scientific and curious lens, here is an author you might want as your guide.  He is no stranger to presenting enormous volumes of information in an easily digestible way, nor is he one to make it cumbersome. His wit and sense of adventure make learning fun.  Moreover, there is no arrogance in his books.  The words “so far,” “unknown,” and “as yet” are sprinkled throughout the text.  He is not afraid to admit when science (or, indeed, when he himself!) has been mistaken, when theories are disproven, educational assumptions found incorrect. He writes with the understanding that our scientific knowledge–like life itself–is still evolving. And like so much of his writing, it only serves to prompt the reader into thoughtful reverie: where might science take us in the future? What will be revealed years, decades, centuries from now, and how will this impact the world?  The creative and wondrous question “What if?” floats like a butterfly through its chapters.

Dr. Martin describes how these seemingly abandoned alligator dens may have indeed been dug when water was present, but that even despite drought, parts of their internal structures may connect with the groundwater table.  Water within the den may have also attracted thirsty birds and animals on the island.  He and his students later found the ravaged corpses and bones from such unsuspecting creatures both in and outside of other forest dens.

“All of this trace evidence told us the alligators could switch from aquatic to terrestrial predation if necessary, like a shark deciding it was going to turn into a lion.  This surprising behavioral transformation and adaptability in alligators was made possible through their dens, which during times of environmental change became all-purpose hunting lodges.” – page 7, “The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet,” by Dr. Anthony J. Martin, Pegasus Books

And thus begins his exploration of the animals—including humans!—worms, insects and birds that have created sanctuaries below ground.  Burrows, he posits, have made survival possible throughout Earth’s history, and these underground homes have made and continue to make enormous impact on life above ground.

“The bigger picture behind these everyday observations of many holes in the ground, however, is that the long history of these burrowing invertebrates completely altered global environments, from the deepest sea to the highest mountains, and even affected the atmosphere and climate.  In short, the entire surface of our planet is built upon one big complex and constantly evolving burrow system, controlling the nature of our existence.” – page 14, “The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet,” by Dr. Anthony J. Martin, Pegasus Books

Dr. Martin encourages us to take a closer look at a generally overlooked part of our world. That closer look involves fascinating details about creatures and places one may not have realized existed.  Burrowing owls–with their photogenic and often amusing images–may be familiar, but perhaps not so much the charming fairy penguins of Tasmania, or the alarming assassin flies associated with gopher tortoise burrows, who both kill and start digesting their hapless victims with an injection of neurotoxins and enzymes.

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Image of burrowing fairy penguins, courtesy of Getty Images
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Slideshow of burrowing owls, courtesy of Getty Images

 

Perhaps the most powerful section of the book—one that really drives home his point about survival underground—involves the eruption of Mount St. Helens in Washington State thirty-seven years ago.

Whether you’ve only read about it or whether you’ve actually visited, Mount St. Helens is a stark reminder of how devastating Nature can be.  After a couple of months of earthquakes, the volcano erupted in the morning of May 18th, 1980. Not only did it obliterate everything in its path, the eruption and its aftermath killed 57 people and all of the wildlife within about 150 square miles.

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Image of Mount St. Helens before the eruption of 1980, photo by Jeff Goulden, courtesy of Getty Images

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Image of Mount St. Helens today, courtesy of Getty Images

Here, Dr. Martin uses creative nonfiction (or ‘narrative nonfiction’) to help illustrate how, despite this traumatic event, the entire area made a comeback.  Loowit, a sweet little fictional pocket gopher, takes the reader through some of the natural events that transformed devastation into renewal and rebirth.

He describes her home: a branching set of underground tunnels and rooms that can reach up to 500 feet long, complete with food storage areas, latrines, and other chambers. Although undeterred by snow, she was, at the time of the eruption, comfortably ensconced in her burrow.  This saved her.  He takes us through how she emerges after the eruption, her confusion, her tentative steps back into a new world above ground, how she and other survivors may have eventually formed communities.

In sum, in a world that now knew mostly death and destruction, these pocket gophers not only survived, but kept surviving, and in so doing, helped bring life back to an area that did not outwardly appear to contain much.

“…these little ecosystem engineers began terraforming the previously desolate landscape, first by helping plants take root and grow. Each individual pocket gopher was capable of overturning more than a ton of soil each year…” – page 262, “The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet,” by Dr. Anthony J. Martin, Pegasus Books
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Image of a pocket gopher, courtesy of Getty Images

“Of the 55 mammal species in the area of Mount St. Helens in May 1980, only 14 survived the volcanic eruption and its collateral damage. Surface-dwelling elk, deer, black bears…and all other large- to medium-size mammals perished. On the other hand, nearly all the small mammals that lived were burrowing rodents…One of the few non-rodent survivors was the tiny Trowbridge’s shrew (Sorex trowbridgii), which (not coincidentally) is also a burrower.  Pocket gophers are active year round, but many other small-mammal species were both underground and still hibernating when the eruption took place.  The fortuitous timing of this disaster at the transition between winter and spring thus greatly enhanced the chances of these minutest of mammals to emerge and thrive.  Of the rodents that had already come out of hibernation, nocturnal species were doubly lucky to have already retired for the day in their burrows when the blast occurred.  Had the volcano erupted at night, many more would have died.” – page 264, “The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet,” by Dr. Anthony J. Martin, Pegasus Books

“For the pocket gopher populations that survived the eruption of Mount St. Helens in 1980, their collective actions were the key to turning a desolate, monochromatic landscape back into a vibrant and verdant one.  From a geological perspective, their effects were astoundingly quick, with partial ecological restoration apparent within just five years of the eruption. Consequently, pocket gophers and other burrowing animals that lived beyond May 18, 1980, send a powerful message about the benefits of burrows for surviving such an ecologically traumatic events, as well as for their role in restoring an ecosystem after it is nearly destroyed.” – pages 266-267, “The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath Our Feet,” by Dr. Anthony J. Martin, Pegasus Books

 

I want more books like “The Evolution Underground” and “Dinosaurs Without Bones.”  Books that tickle my intellect and my sense of humor.  Books that pull me in with their interesting anecdotes, their engaging playfulness, their sensitivity to all genders (ie: not referring to all humans as “mankind” or simply “man”), and their ability to make me think outside the pages.

When I read a book and am left not only with the satisfaction that comes from something that I’ve enjoyed but also an eagerness for more, I know I’ve found a talented author.

Dr. Anthony Martin is, indeed, a talented author.

 

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A sincere and enthusiastic THANK YOU to Dr. Anthony Martin for his willingness to connect by phone and for his generous responses to my questions!  It was a pleasure and an honor to be able to speak with him, and—like his writing—he made it fun!  I eagerly (if impatiently) await any possible future work.  

FULL DISCLOSURE: The author of this blog loved Dr. Martin’s previous book with Pegasus, “Dinosaurs Without Bones,” and thus, jumped at the chance to review his latest work (fully predisposed to embrace it) by requesting a review copy from the publisher.  I am very grateful to Pegasus Books for the opportunity to do so. I am specifically grateful to Deputy Publisher, Jessica Case, with whom it was wonderful to work!

Fossil Landscape Revealed: Reading the Rocks in New England Summits

It’s remarkable to think that we are discovering ice on a dwarf planet 4.67 billion miles (7.5 billion kilometers) away from Earth, at a time when we are still unraveling clues to the ice that once shaped this planet.

Two New England geologists have spent years studying the rocks and traces left by ancient glaciers in the White Mountains, the northern stretch of the Appalachian Mountains in New Hampshire and Maine. This past October, they co-authored a paper in Geology with 3 other scientists.  And in it, they revealed that the highest summits in New England were covered by solid ice during the Last Glacial Maximum.

 

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View from the summit of Mount Moriah in New Hampshire looking at the White Mountains’ Presidential Range; image by Cappi Thompson at Getty Images.

 

But what does this mean? And why should we care?

“This question about whether or not the New England summits were covered by an ice sheet is long standing, going back over 100 years,” explained Dr. P. Thom Davis by phone.  “And one reason this question is important is because continental ice sheets take a long time to build up, and as they build up, they reduce global sea level.   So ice sheet thickness has implications far beyond just New England.”

Dr. Thom Davis of Bentley University and Dr. Paul Bierman of the University of Vermont actually wrote and presented the paper at the annual Geological Society of America conference in 1999, but they didn’t publish it until 2015.

“We sent a draft around informally to some colleagues,” said Dr. Davis, “and they sort of were giving us a hard time, wanting us to go back and rethink a lot of the implications. And then one thing led to another, and we just kept rethinking and rethinking for the next 15 years.”

“It was a much more radical proposition in 1999 than it is today,” explained Dr. Bierman. “Since then a whole lot of work has come out of the Arctic. So when we finally submitted this now, I guess it was a surprise, but it wasn’t unexpected.”

That ‘radical proposition’ involved whether or not ice covered the mountains, whether it was a certain type of ice, and therefore whether it did or did not preserve “fossil” or “relic” landscapes.   These ideas have been pondered (or dismissed) by various geologists since the mid 1800s.

While the term “fossil landscape” might inspire images of preserved prehistoric environments suffused with traces of ancient life, this is not at all what it means.  Rather, it refers to the geology left behind by cold-based ice–ice frozen all of the way to the ground–that both shielded rocks from the effects of cosmic rays and slowed erosion.

Think of how much impact an enormous sheet of ice can have on an environment.  When ice is not completely frozen to the ground (warm-based ice), water runs through it, pulling dirt, rocks–and the glacier itself!–along with it.  The ground erodes; the debris is carried elsewhere. Remnants can be seen in boulders scattered throughout New England.

Notice the shape of the valley in Crawford Notch, NH.  This valley is a result of glacier ice moving through the environment, albeit at a remarkably slow speed. Image by Mark Zelasko at Getty Images.

 

Images of a boulder (perhaps a glacial erratic: a rock carried by a glacier and deposited in another location in geologic terms) in Salisbury, NH; photos taken by the author

 

“The word ‘fossil landscape’ sort of worried me from the get-go because of how it might be misconstrued to having more of a biological context, like mammoth bones,” stated Dr. Davis, in reference to the press release describing their work. “We’re looking at the age of exposure, the length of time those surfaces have been exposed to the cosmic ray bombardment.”

Drs Davis and Bierman collected samples near to or on the summits of Mt. Katahdin in Maine and Mt. Washington and Little Haystack Mountain in NH during the 1990s.  Their ‘radical’ suspicion–that these summits were indeed covered by solid ice–could only able be proven recently with advanced technology.

Before that, they–like their peers in the last two centuries–relied on visible clues: the type of rock on summits and in valleys, striations (or grooves) in the rocks that may have been made by  ice, the type of sediment in the valleys and whether this indicated the type of glacier that might have helped create them.  And one of the biggest clues?

Erratics.

“That is,” Dr. Davis explained, “stones that have been transported from another location.”

“Two centuries ago, scientists might have argued [that erratics] were deposited in these high locations by great floods,” he continued. “But that pretty much ended with Agassiz’s glacial theory in the middle of the 1800s.”

He is referring to Louis Agassiz, an eminent Swiss biologist and geologist who taught at Harvard, and perhaps the first to support the idea that these summits were covered by an ice sheet.  It is important to note, however, that he believed that ice sheet was a local glacier rather than a vast continental ice sheet.

Prior to this, geologists such as Charles T. Jackson–the first NH State Geologist–or Edward Hitchcock (of trace fossil fame) believed that a flood complete with icebergs was responsible for misplaced boulders. Striations could be explained by the force of rock against rock from powerful currents within that water.

British citizens Mary Horner Lyell and her husband, Charles–another well-known geologist from the 1800s–explored these mountains in 1845, including a trip up Mt. Washington on horseback. Lyell attributed erratics to melting icebergs.

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Frozen tower and communication equipment at the summit of Mt. Washington; image by Onfokus at Getty Images.  Charles Hitchcock — son of Edward and Orra Hitchcock — helped create this year-round weather station.  He was a NH State Geologist and a Dartmouth professor. 

NH geology took a step forward with James W. Goldthwait and then later his son, Richard, in the 1900s.  They proposed that New England summits were covered by solid ice–not warm-based ice–and by a continental–not a local–ice sheet.

“[James W. and Richard P. Goldthwait] recognized this importance long ago, from the turn of the last century,” said Dr. Davis. ‘They both recognized very fresh looking erratics. The only way erratics can arrive on these summits is by continental ice sheets.”

“They made a really good case that the last ice sheet that dropped these erratics on the summits happened during our last glaciation about 20,000 years ago. [I]f the summits had been nunataks during the last major glaciation about 20,000 years ago, then the erratics should have been more weathered, the soils should have been more developed on the summit areas, and the bedrock should have been more weathered, as well.”

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Baxter Peak of Mount Katahdin in Baxter State Park, Maine. View from Knife Edge Trail; image by Posnov at Getty Images.

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Mount Katahdin is the highest mountain in Maine at 5,268 feet (1,606 m). Katahdin is the centerpiece of Baxter State Park: a steep, tall mountain formed from underground magma; image by Simon Massicotte at Getty Images.

The debate about the type of ancient ice in the White Mountains was dropped for a few decades, slowly regaining interest in the 1970s.  But it wasn’t until the recent paper by Drs. Bierman and Davis that proof lent itself to solving the issue.

“[Our method was to] count the abundance of very, very rare isotopes,” Dr. Bierman explained, “And, by that we mean isotopes of the element beryllium and the element aluminum.”

“The beryllium isotope with a total mass of 9 is the normal stuff that you find in nature. The beryllium isotope with a total mass of 10 per atom is extremely rare. And in order to measure these isotopes, we needed the technical ability to do that, and that didn’t come about until the late 1970s with a device called the accelerator mass spectrometer. These are very large, very expensive, difficult to maintain, and rare beasts. Over the past 30 years, they’ve been used increasingly by geologists to make the kinds of measurements that we did.”

“We also used cosmogenic carbon-14,” he continued, “which is an isotope with a much shorter half-life, about 5,730 years. And what that means is that when a rock is exposed to cosmic rays at the surface and then buried, that carbon 14 disappears much more rapidly than beryllium 10 and aluminum 26 isotopes.

“[Data from the accelerator mass spectrometer] tells us the [exposure] age because we can count the number of carbon-14 atoms, just like we can count the beryllium-10 atoms. We know that these are produced at a certain rate every year. It’s a very low rate.

“For beryllium-10, it’s just a few atoms per year per gram of material that we’re measuring. It’s a little bit more for carbon-14.  And since we know how quickly they’re made and we can count how many atoms there are, we can calculate an age–or a residence time–near the surface.”

“A lot of these ages from our exposure dating,” added Dr. Davis, “were coming out much older than we expected, much older than the last glaciation from the summits of both Katahdin and Mt. Washington.”

 

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A view of Mt Washington and Mt Madison along some farmland in Shelburne, New Hampshire during winter; image by Cappi Thompson at Getty Images.

“I think the Goldthwaits were primarily looking at these kinds of qualitative data, like how fresh the erratics in the bedrock were,” Dr. Davis offered. “And based on that, they probably weren’t exposed very long.  But as it turns out, weathering varies dramatically to different latitudes, so is not a very quantitative method. That’s all we had, though, until these cosmogenic radionuclides became available for measuring.”

“The main point of our geology paper is that, apparently, even at temperate latitudes, the higher elevations may have been overrun by ice sheets that were frozen to the bed, leaving what we call ‘relic landscapes,'” he concluded.

“From a geologic point of view,” Dr. Bierman continued, “it points to the complexity of the evolution of the New England landscape. It’s another piece of the puzzle in how this landscape evolved over time.”

 

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Sunrise clouds above the White Mountains’ Presidential Range in Jefferson, New Hampshire; image by Cappi Thompson at Getty Images.

 

Old Man of the Mountain–an iconic NH rock formation, one that seems appropriate to share in a blog post on geology–on April 26, 2003, seven days before the rocks of its face collapsed. A late spring snow fell the night before. Image by Jeffrey Joseph, public domain, Wikipedia.

Dr. P. Thom Davis and Dr. Paul Bierman not only introduced me to a new science, they also piqued my interest in it. Basic geologic vocabulary was foreign to me. I delighted in discovering the meaning behind new words (nunataks, moraines, varve records, basal thermal regime!) in order to better understand their work. Thanks to their time and their research, I now look at the world around me with much more discerning eyes, especially at the many boulders erratics that scatter the landscape.  Fossils in New England may be scarce, but rock formations are not.  I extend a sincere and resounding THANK YOU to both, for their help, their graciousness and the fun three-way conversation we had discussing their paper!

Thank you to Kea Giles at the Geological Society of America for sending me a copy of the paper!

I highly recommend the book “The Geology of New Hampshire’s White Mountains” shown below, co-authored by Dr. P. Thom Davis. It is a fascinating account of NH geology and a great introduction to geology itself.

Woodrow Thompson, another co-author of that book, wrote an engaging account of the history of NH geology (paper is listed below). It was a great help to me in writing this piece, and I encourage anyone interested to read it! 

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References:

1. Fossil Landscapes in New England, GSA press release, October 26, 2015
2. Cold-based Laurentide ice covered New England’s highest summits during the Last Glacial Maximum, Paul R. Bierman, P. Thompson Davis, Lee B. Corbett, Nathaniel A. Lifton, Robert C. Finkel, Geology, October 2015
3. History of Research on Glaciation in the White Mountains, New Hampshire (U.S.A.), Woodrow B. Thompson, Géographie physique et Quaternaire, Volume 53, 1999
4. The Geology of New Hampshire’s White Mountains, J. Dykstra Eusden, Woodrow B. Thompson, Brian K. Fowler, P. Thom Davis, Wallace A. Bothner, Richard A. Boisvert, John W. Creasy; Durand Press, 2013