6 November 2015

Friday fold: ptygmatic in northern India

Another image from northern India’s Himalayas, courtesy of Martin Schmidt:


The “intestine-like” aspect of this fold has a descriptive adjective in geology: ptygmatic.

Gorgeous! Thanks for sharing, Martin.

Happy Friday!

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2 November 2015

Norman Bowen’s papers

I got a special treat the week before last – one of my students this semester works at the Geophysical Laboratory of the Carnegie Institution in Washington, DC. During our unit on igneous rocks, he was prompted by the “Bowen’s reaction series” discussion to let me know that Norman Bowen’s notebooks were still extant at the Carnegie. He invited me down to check them out, and I readily accepted.

Here’s Bowen, in the field a century ago, sampling rocks:


Among the documents I got to examine during my visit was this first edition of Bowen’s book The Evolution of the Igneous Rocks:


Inside is a diagram that every introductory geology student will recognize:


Inside the front cover of this same book, you can see Bowen inscribed it to Hat Yoder, and a copy of Bowen’s obituary is tucked behind a portrait of him:


Norman Bowen’s degrees: Bachelor’s and PhD:


… and a master’s degree, too:


I also was privileged to examine Bowen’s experimental notebooks:


Here’s Bowen’s notebook on plagioclase, for instance:


Open it up, and here’s what you see:


Did you catch the diagram sketched out at the top of that page? It’s the plagioclase solid solution, from Ab (albite) on the left to An (anorthite) on the right, showing composition of solid and melt (on the horizontal axis) as melt cools to make solid rock. The vertical axis is temperature. Petrology students will be keen on this one (or maybe not):


This simple sketch is foundational to understanding the compositional evolution of an evolving magma/rock system.

I love this one: “Something wrong!!!”





This one is labeled “Sinking Crystals”:


Inside, there is this:


Once crystals of minerals such as olivine form in a cooling magma, they may sink to the bottom of the magma chamber (in this case, the artificial magma chamber) because they are more dense than the surrounding melt and form a cumulate layer. Knowing this is key to understanding how the Stillwater Complex in Montana formed, or why the Palisades Sill along the Hudson River in New Jersey is 25% olivine by volume at the bottom, but only 1% at the top.

Much of what we understand about igneous rocks was first worked out by Bowen, doing experimental work at the Carnegie. Geoscience owes him a huge debt.

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30 October 2015

Friday fold: Himalayas, northern India

My colleague Martin Schmidt of the McDonogh School, who I know through the National Association of Geoscience Teachers eastern section, recently shared a bunch of fold photos with me. They have a “dated” feel because they were originally shot on slide film, but the folds themselves of course are timeless. I’ll be featuring a bunch of them here in the weeks to come.

Here’s a scene Martin captured in northern India:


Happy Friday!

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29 October 2015

“Making North America,” episode 1: Origins

The PBS series NOVA has a three-part series coming out next week called “Making North America.” Hosted by the director of the Smithsonian Institution’s National Museum of Natural History, Kirk Johnson, the series will explore the tectonic assembly of terranes that resulted in the bedrock of the continent, the panoply of diverse creatures that have dwelled here in the past, and the human prehistory of our continent. I was given press access to review the episodes in advance. I’ll cover them one by one.

Episode 1 is the most explicitly geological of the three. It begins, of course, at the Grand Canyon, and while that location is almost a cliché (as is the red-tailed hawk call they played over footage of a wheeling vulture), they did something new, innovative, and worthwhile with it: While on a (gratuitous) rappel down a cliff of Esplanade Sandstone, Kirk made the point that each layer in the Grand Canyon’s stratigraphy is a snapshot of conditions on Earth’s surface at one point in time. Then, through CGI, individual layers slide out of the canyon walls, each depicting on a hovering slab of rock the depositional environment that is the best interpretation of that layer’s formative conditions: shallow seas, sand dunes, swamps, etc. This is the point I try to drive home with my Historical Geology courses, and the floating slabs of ancient depositional environments was an elegant way of expressing it.

A consistently used, though understated, digital enhancement was showing a brief glowing grid pass over Kirk’s glasses, and then in the next scene you see that grid “mapping” the landscape under his gaze. It’s as neat a representation as I’ve seen of “seeing the world through geology colored glasses.”

Another CGI effect was the evolution of paleogeography over time, using what appears to be a “tweening” method for extrapolating steps between static paleogeographic reconstructions. The technique, however, results in a jittery sort of time lapse, as the continental bits pulse and squirm back and forth. To me, this raises the possibility of an intriguing test of the validity of these paleogeographic reconstructions – do the sudden, temporary reversals in motion accurately reflect our understanding of the data that under-gird the paleogeographic interpretations? Of course, plates can shift direction, but watching these pulsating blobs of crust carom across the screen struck me as mildly inelegant, perhaps even carrying an unparsimonious scent with their inconsistent velocities.

Speaking of CGI, I think the simplest and most effective use of digital special effects were on the segment that looked at the San Andreas Fault. At one point, Kirk and another geoscientist sit on the North American Plate at Tomales Bay, and across the water, Point Reyes heads northwestward at several feet per second. Cool effect. A moment later, the camera swoops over the Hollywood sign and crests the ridge to reveal… the Golden Gate Bridge! It’s a clever way of showing the eventual juxtaposition of Los Angeles and San Francisco through fault motion.

Another fun moment came during a scene prospecting on an Alaskan beach for fossil palm fronds… The talented artist Ray Troll, Kirk Johnson’s companion in the awesome Cruisin’ the Fossil Freeway, makes a cameo appearance. Kirk himself delivers a solid performance – the enthusiastic, knowledgeable goof. His easy-going demeanor makes him very approachable as host, I would say. Some of the conversations that ensue are unbelievable as verbatim exchanges between two professional geologists, but I think the acting parlays the simplified essential points for the non-specialist audience.

I appreciate the attempt to make the point that partial melting of basalt can yield a magma with a more felsic composition, but it was definitely presented in a lowest-common-denominator kind of way: glossing over the details but making the point that continental crust is derived from the recycling of oceanic crust. Much of the exposition in the episode is like this: simple enough for non-specialists to comprehend, but probably too simplified for specialists to fully embrace. There’s a lot of repetition too – which would probably make the series a good choice for school groups.  A good deal of attention was paid to the Mid-Continent Rift (under Lake Superior), and I liked referring to Rodinia as a continental “group hug,” as well as upgrading Pangaea from a supercontinent to a megacontinent. I cringed at the use of “Taconic Mountains” for the Taconian Mountain range, Alpine in size and Ordovician in age. (You can visit the Taconic Mountains today – really, we are a vocabulary rich science, and there’s no need to use the same geographic term for ancient huge mountains and modern piddly mountains.) There was a cool exploration of thinking through the discovery of an unusual geological observation, and coming up with a valid interpretation (seismically-induced sand volcanoes cross-sectioned at Zion National Park).

One final note: of the named experts that were interviewed or featured in the episode, two were women and two were men. Excellent job, NOVA, on getting the gender balance right.

“Making North America,” episode 1: Origins will air next Wednesday on your local PBS station.

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28 October 2015

Between the World and Me, by Ta-Nehisi Coates

coates I have mentioned that I’m on a year-long effort to diversify my reading list. There are so many great books to be consumed, and I’ve been spending far too much time with white, male authors. When I heard a few weeks ago that the new cadre of MacArthur fellows was announced, I read their biographies and thought about their work. Ta-Nehisi Coates was among them, and prominently mentioned in his bio was this book, Between the World and Me, a book-length letter from Coates to his teenaged son, on the topic of being black in America. This stirred up a memory of hearing this same book highly praised recently in social media, and so this endorsement from MacArthur served as a reminder me to seek it out. There were no audiobook versions available, so unlike many of the books I review here, I actually read this one the old-fashioned way, on paper.

I review it here with a mix of imperative and trepidation. The topic is vital and urgent, but also highly charged with emotion. I worry that I might say something oafish as I process the thoughts Coates has stirred up in my mind. If I misstep, please: forgive me. My intention is to further the discussion in pursuit of justice. It also occurs to me that even if I don’t mess up in my discussion, that a portion of my readership will be upset at my bringing up the topic of race. They may feel it’s inappropriate to talk about. Certainly, they may legitimately complain, it has nothing to do with geology. I don’t really care about them, though: I feel morally compelled to call your attention to Coates’s book – it puts a compelling issue in the glare of our attention, and immerses the reader in the perspective of black existence that is at once visceral and highly intellectual. There are grave injustices being carried out daily in our nation, and everyone deserves better than to permit inequality to persist. Let’s care enough to take a closer look.

It’s a unique book in my experience. It’s a letter to his son, yes, but it’s also a letter to black youth everywhere, and to Americans everywhere, on the insidious persistence of racial inequality in our society. It is impassioned and erudite, and mixes personal history with U.S. history with keen socio-psychological analysis of patterns in American society. There are statistics quoted, but more often the language is the rich, evocative, and personal. Coates has a voice characterized by keenly-selected words and examples, and a mix of familiarity (Trayvon doesn’t need a last name specified) and intentionally specific semi-awkward formality (“people who need to think that they are white”).

Key elements in the book are his focus on the risk of bodily harm, on the imposition of class structure, on the sweep of history and the unchanging essentials of the problem of racism, and a fairly bleak outlook for the future of the problem. Coates writes with an expectation that racism in America is something you can bet on. It is a feature of our society rooted in our awful past, on the fact this nation was built with the labor — the bodies, as Coates would say — of enslaved people. It is a blatant aspect of our modern life, exemplified time and again by incidents both national and newsworthy (Michael Brown’s murder in Ferguson, Missouri) or fleeting and personal (a white woman pushing Coates’ son out of the way on a city sidewalk, triggering a shouting match and a threat to Coates: “I could have you arrested!”). There’s no reason to expect it to change any time soon – It’s reinforced constantly, he argues. Coates doesn’t buy religious claims of redemption after death – something that he admits sets him apart from most American black people. He doesn’t share their hope for better days ahead, for the meek inheriting the Earth. Instead, he’s a realist, focused on the here, and the now. This is something he and I share – without the nice happy afterlife to make it all better, our lives are all we have. The problem of racism exists here, now, in this world – and that’s the place to fix it. By the time we die, it’s too late.

You’ve got to be really careful, Coates warns his son. Even if you are careful, you can still get destroyed by the racist system in which you live. You can go to the store and buy Skittles and be shot dead, your murderer free to walk the streets. You can play your music too loud, and be shot dead, your murderer free to walk the streets. You can go to college and work on a degree and drive over to your fiancee’s house for dinner and and be shot dead, your police officer murderer free to walk the streets. You can sell cigarettes on the street, and police officers who choke you to death can trust in their own eventual exoneration. You won’t be treated equally, he tells his son – though you deserve to, though on paper you should officially be – the reality is that you will not be. You are black in a society that destroys black people. You need to watch out for yourself.

This is sobering stuff. I am a child of privilege and I am “white” by almost any definition of the descriptor. Coates’s repeated use (I think, in every instance) of “people who need to think that they are white” instead of “white people” was provocative to my mind. Do I “need to think that” I am white? I wouldn’t hazard an answer, because even if it’s unintentional, I feel certain that I’m probably doing something to perpetuate the status quo. I feel passionately that every person who I share this planet with should be treated as equal in inherent value. “People who need to think that they are white” is essentially synonymous with “people who need to think that they are better or more important than other people” – it’s a reflection of the ranking of value that many people apply as they look out at a world full of other people. Professors have value equal to their students. Women have the same value as men. A wealthy person’s inherent value is identical to a person with no money at all. Convicted felons are equal in value to upstanding citizens. Somali children are equally important as American children. Every instance where the rich gain societal advantage over the poor, where men subjugate women, where a black child is denied an opportunity available to a white child, where tribalism manifests as xenophobia — is an inequality and therefore an injustice. I may here be scolded with “It’s unrealistic to expect this to change,” and that may be true – but it should change. If we can see the problem clearly, we can work towards a solution. I’m sick of shoulders being shrugged at others’ misfortune.

This really bothers me, but I should emphasize that I understand it doesn’t threaten me the way it threatens Coates or his son. It doesn’t threaten me with bodily harm, the way socialized racism threatens my black students, the way socialized sexism threatens women in Saudi Arabia or Shenandoah County, the way America’s exaltation of wealth threatens those who don’t have any money. In spite of my intentions of social justice, however, I wonder how many racist lessons I’ve internalized merely by being a cog in the American machine. I guess the best I can do is use my position as Coates uses his: to call attention to a situation that has been unjust forever, and continues to be, in front of our faces, every day. I can use my pulpit here on the blog to remind my readers that they have an opportunity to help correct injustice, starting by embracing an awareness of it.

This quotation, one paragraph from the middle of the book, I think demonstrates what the book is about and how Coates approaches his material:

That wisdom is not unique to our people,but I think it has special meaning to those of us born out of mass rape, whose ancestors were carried off and divided up into policies and stocks. I have raised you to respect every human being as singular, and you must extend that same respect into the past. Slavery is not an indefinable mass of flesh. It is a particular, specific enslaved woman, whose mind is active as your own, whose range of feeling is as vast as your own; who prefers the way the light falls in one particular spot in the woods, who enjoys fishing where the water eddies in a nearby stream, who loves her mother in her own complicated way, thinks her sister talks too loud, has a favorite cousin, a favorite season, who excels at dress-making and knows, inside herself, that she is as intelligent and capable as anyone. “Slavery” is this same woman born in a world that loudly proclaims its love of freedom and inscribes this love in its essential texts, a world in which these same professors hold this woman a slave, and when this woman peers back into the generations all she sees is the enslaved. She can hope for more. She can imagine some future for her grandchildren. But when she dies, the world –which is really the only world she can ever know– ends. For this woman, enslavement is not a parable. It is damnation. It is the never-ending night. And the length of that night is most of our history. Never forget that we were enslaved in this country for longer than we have been free. Never forget that for 250 years black people were born into chains – whole generations followed by more generations that knew nothing but chains.

You will note there that Coates writes with righteous passion. The passage speaks for itself, but it exemplifies the book’s second person perspective, the literary sense of description, the grounding in physical reality and real life, the personal focus and the empty hollow where the Golden Rule should apply, the infusion of history, the tone of admonition. To me, it feels intense, and that too is representative of the imperative feel of the entire book.

What advice will I have for my own son when he comes of age? Certainly the advice would overlap with the advice Coates gives to his son, but largely it would cover different terrain. Growing up and transitioning to manhood will be different for a child who looks like mine than for a child who looks like Coates’s. This is patently, wildly unfair, and so perhaps the best bet for rectifying the injustices my son will encounter is to raise his awareness, nurture his sense of empathy, and teach him techniques for enabling the advance of equality and justice. Perhaps I should give him Coates’s book as part of that effort.

Why is it so hard for us all to treat other people the way we want to be treated, and strive to help all people be treated justly? How will I answer my son when he asks me why people are so awful to each other, so endlessly cruel and hateful?

Walk a mile in Ta-Nehisi Coates’s shoes. Read this book.

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27 October 2015

Corridor H virtual field experience

My Historical Geology class was in for a new experience for the semester’s capstone field trip. Before we headed out into the field (to the exceptional roadcuts along Corridor H in Grant and Hardy Counties, West Virginia), we had them examine all the outcrops virtually, in the comfort of the classroom, using digital imagery. I say “we” because this initiative was a collaboration with my colleague Alan Pitts, who developed the Corridor H virtual field experience (VFE) as an ancillary project associated with his pre-GSA field trip to Corridor H (Trip #408). Alan is a long-term collaborator on my GigaPan project, the Mid-Atlantic Geo-Image Collection, and he’s responsible for making dozens of GigaPans of the roadcuts on Corridor H. Alan used Team M.A.G.I.C.’s huge collection of GigaPans from that road, and embedded them all in a single Google Earth ‘tour’ for geographic context. We had the students complete the associated assignment in class in groups last Wednesday, and then headed out into the field on Saturday.

We had them evaluate this GigaPan in class, for instance:

And then took them to the site:


Likewise, we had them examine this outcrop of Pennsylvanian sandstones, shales, and coals first in the virtual realm, and then later in person.



We conducted informal interviews during the in-class session, after concluding the virtual field trip experience, and polled the students after the real field trip. Alan will also be sharing another less-local-student-focused version of the VFE with his GSA field trip participants. He will present the results of both of these applications of the Corridor H VFE on Sunday at the meeting of the Geological Society of America in Baltimore. If you will be at the meeting and wish to learn more, please join us for Alan’s talk.

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26 October 2015

Tool marks, trace fossils, and flute casts from the Brallier Formation

Another gem from Saturday’s Historical Geology field trip: the bottom of a fine sandstone bed in the Devonian Brallier Formation, showing a variety of primary sedimentary structures, including tool marks, trace fossils, and several flute casts. Current flow direction here would have been from upper left toward lower right.


Here’s a version of the photo with a few of these features highlighted:

IMG_1733 copy

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25 October 2015

Cool fossils from the Clearville member of the Mahantango Formation

On Saturday, I took my historical geology class on their field trip out to Corridor H, West Virginia. We made a stop at the Mahantango Formation outcrop exposed on the eastbound exit ramp near Baker, and poked around there for fossils. These Devonian-aged siltstones are chock full of invertebrates including rugose corals, crinoids, articulate brachiopods, and even trilobites. Here are two of the best fossils we encountered there:

A trilobite pygidium (or half of one, anyhow):


A rugose coral mold:


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23 October 2015

Friday fold: Apennine phyllites

Another one from Samuele Jæger Papeschi:

NE verging recumbent F2 folds in Paleozoic phyllites – Filladi di Buti fm., Punta Bianca, N. Apennines, Italy


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21 October 2015

Seven new GigaPans from Axel Heiberg Island, Nunavut

One of the cool things about my plan for the GEODE grant from NSF is to put GigaPan imaging systems in the hands of people who will take them to cool places. I purchased five loaner GigaPan rigs, and they have gone out in the field with various people, but I think that the images I will show you today are the coolest we’ve yet produced. All seven of them come from Carol Evenchick, Emeritus Scientist with the Geological Survey of Canada. Carol and I met last year at GSA in Vancouver, and made a plan for her to take one of my loaner rigs up to Axel Heiberg Island with her this summer.

Where is that? It’s way, way, way up north in Nunavut, at the latitude of northern Greenland:

axel (Greenland for scale)

The images are finally posted publicly, and you should check them out. They contain a wonderland of cool geological features:








These images range in size from 1 to 5 gigapixels, and they feature all kinds of fascinating, unvegetated geology: there are sedimentary features, volcanic features, modern fluvial geomorphology, and of course big old glaciers lurking in the background of many shots. Plus there are some nice example of the accommodations when the GSC is on a trip in the high Arctic. There’s a lot to see and think about.

Are you going someplace awesome and wouldn’t mind taking a few GigaPans while you are there? If so, I’d like to loan you one of my GigaPan kits. You can email me with the particulars, or we can talk at GSA in ten more days, perhaps over a beer in the poster hall – just like Carol and I did. Great things come from networking at conferences!

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