23 November 2015

Seveneves, by Neal Stephenson

7evesAt first, I thought the titular Seveneves referred to fragments of the Moon. It blows up on the first page of the novel – or disaggregates anyhow, into seven big chunks. But these start knocking into one another, breaking off smaller pieces, and these bang into each other, making more pieces.

Soon, there are a lot of pieces.

Spoilers galore follow, as I feel obligated to outline the scope of the story: The mathematics of making a lot of pieces from the seven originals is a scientific problem that catches the interest one of the main characters, a PR-savvy astronomer who’s clearly modeled on Neil DeGrasse Tyson. He runs the numbers and finds that the system of moon fragments’ auto-catalyzing fragmentation will go exponential about two years after the moon broke up. This isn’t good news for the surface of Earth. Humanity has two years to get a space colony going, and stock it with enough genetic information to kick-start human civilization some thousands of years in the future after the “Hard Rain” ceases and the surface of the planet becomes habitable again.

The politics and the logistics of who to save kick in, and basically everyone pitches in, trying to make this project a success, since the future of the human race and life on Earth hinges on it. The novel is set in the here and now, and Facebook and Twitter figure into the plot. By the time the Hard Rain begins to fall and >7 billion people (and every other form of life) on the surface are killed, about a thousand folks are in orbit in a hastily-constructed “Cloud Ark,” centered on the former International Space Station. One of them is a stowaway – the conniving President of the United States, a woman who instantly starts sowing discord in the rank and file. There’s a daring mission (by an Elon Musk like character) to bring a comet into the Ark for fuel, and various other instances of serious problem solving. Each of these challenges is addressed frankly and in detail, with plenty of exploration of perigee and apogee, ΔV and the physics of living in zero gravity amid near constant bombardment by cosmic radiation. The first two-thirds of the book has a lot of discussion of orbital mechanics. You should know that going in, and you should also know that it’s not boring. While the technical problems can be solved to greater or lesser degrees, the human problem (of how to get along) is presented as a constant. People make moves, other people respond, and there are deaths. Soon, there are waaaaaaaaaaaaaay fewer people left than is in any way acceptable, but one of them is a geneticist, and her lab equipment survives, and after a brief discourse on parthenogenesis and heterozygosity, we see her plan for furthering the human species – essentially, one of each of the surviving women is author of a ‘race’ of future humans.

Fast forward 5,000 years. The final third of the book examines the results, specifically the return to Earth mid-way through the terraforming effort put into effect by the descendants of the Seven Eves. Once there, they find to their surprise that they aren’t alone. As the various strands of humanity become reacquainted, there is some static, and again some awful behavior, as well as some positive connections and unexpected outcomes. I’ll avoid going into too much. That part of the book feels like a typical science fiction novel, so the plot is perhaps more important than the set-up.

But what sticks with me about the book is the set-up – the first two thirds of the book that posit this extraordinary circumstance, and examine how we would deal with it. If we knew the planet would be totally lethal in two years, and would remain uninhabitable for five millennia, how would we act? What would we do? This, to me, is the most interesting thing about Seveneves – its examination of the real-world fallout from that initial extraordinary premise.

I enjoyed the book. I don’t read much science fiction, but this held my attention, and I’ll seek out more from the author, Neal Stephenson. It would make a great movie.

Here’s a review from NPR that speaks to my experience reading it – in particular, the balance Stephenson seems to get just right about explaining things completely but without letting your attention span down.

I found out about the book from the Don’t Panic Geocast, which reviewed it alongside The Martian. I’d say The Martian was the better book, but it’s kind of comparing apples and really complicated oranges to say that. They are both worth reading.

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20 November 2015

Friday fold: recumbent limestones of coastal Grosseto

Samuele Jæger Papeschi not only provided this week’s Friday fold, but he also serves as its sense of scale:
According to Samuele, these are:
folded metalimestones in Punta delle Rocchette, Grosseto. This are pretty interesting transected folds, showing about 10 degrees of foliation dip in respect to their axis
Thanks for sharing, Samuele, and happy Friday, all!

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19 November 2015

A little geologic history before breakfast

While in Baltimore for the GSA meeting a few weeks ago, one morning (on my way to breakfast at Miss Shirley’s), I walked past a building and saw some cool geological features in the building stone used to face its exterior.

It was a coarse reddish limestone, at first glance kind of similar to “Tennessee Marble” such as may be seen on the interior of the National Air and Space Museum in Washington, DC, or the exterior of the National Museum of American History. It had lots of fossil chunks in it, including this crinoid:


Primary features such as bedding were clearly discernible, as well as mottled zones of what appeared to be bioturbation:


Here’s a zone that may represent primary sedimentary texture (rip-up clasts) or may be a little fault breccia:


There were also some clear tectonic overprints, including a pressure-solution-induced cleavage, marked by the accumulation of dark-colored insoluble material on the cleavage surfaces:




You can see how the pressure solution changed the shape of the crinoid, not so much by the elliptical cross-section, but by the flat upper left surface, parallel to the trace of cleavage:


Here is another nice example of bedding / cleavage relations in this lovely building stone:




So the overall story recorded by these slabs is: first, deposition of lots and lots of skeletal fragments of invertebrates (CaCO3) in an ancient, relatively high energy (coarse grain size) marine setting (based on the fossil content). It may have resembled a scene offshore from modern Florida. At times, the accumulation rate must have been moderate to slow (in order to get enough time for the bioturbation to occur). Periodically, storms may have pummeled these shallow waters (as hurricanes mash into Florida today) in order to make the rip-up clasts. Later, after lithification, the rock was squeezed under some sort of differential stress, oblique to bedding. This triggered pressure solution of the calcite, and allowed shortening of the fossils parallel to σ1, as well as the development of cleavage. Was this a tectonic compression? Maybe – if the bedding stayed in its original horizontal orientation. However, if the strata were rotated by 30° or so post-deposition, compaction under the force of gravity alone could explain the development of pressure solution seams ~parallel with horizontal, but oblique to bedding. Because I don’t see any of the “bed of nails” style of stylolites that are typical of such gravitational compaction (in say, the “Tennessee Marble”), I’m going with the tectonic cleavage interpretation as my leading hypothesis.

Gosh! Contemplating all that was better than coffee to wake a person up. I continued on my walk to breakfast thoroughly invigorated. One great thing about cities is they have lots of cool rocks on display, almost everywhere you look!

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18 November 2015

Beach sand of coastal Maine

You could use a macro GigaPan of some pretty sand, I think.


That’s sand from near Acadia National Park, in Maine. Exploring it, you can find both small chunks of Acadian granite, and green rods that are sea urchin spines. It’s fun – check it out.

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17 November 2015

Hitting a nerve with popular posts

I blog here a few times a week, when I can manage it. Mostly I focus on new things I discover on field trips, advances in geologic imagery, and structural geology.  I get about 500 readers per day. But occasionally I write about other things, like creationism or current events disasters like earthquakes, and those posts garner a lot more attention. They get shared and reshared and spread out. My most popular posts to date have been about the big Japanese and Virginia earthquakes, a post about climate change vocabulary, “Words matter,” and that testy exchange with Discovery Institute staffer who got upset with me when I wouldn’t let his boss use my photograph in his book.

Speaking of climate change, a post last week on crossing the 400 ppm CO2 threshold for good got a lot of attention. People care about climate change.

The Twitter reaction surprised me: ~1600 people tweeted a link to the post. About 7500 people per day visited the post, and if I’m to believe the Facebook statistics, 14,000 people “liked” the post. This means “The last days of sub-400 ppm CO2” is solidly in the ranks of my all-time top five most popular posts:


It seems that there are three potential topics for a post on Mountain Beltway to go viral: (a) there’s a natural disaster, (b) the post is about creationism, or (c) the post is about climate change. None of my structural geology posts get anywhere near the amount of attention these other topics do – go figure! Human interest in disasters like the Tohoku earthquake is readily comprehensible: it’s a current event, and people are dead because of it. We all want someone knowledgeable to help us understand events like that. Creationism and climate change denial are the two most prominent forms of pseudoscience/antiscience in modern American discourse, and so discussing them is of interest to a lot of people. Most of the attention I got for those posts was positive, but going viral elicits negative commentary too. People have strong opinions on climate change and evolution. You get the good, and you get the bad. Compare and contrast:


I guess some people are always going to be negative, or aggressive in their demeanor (one called me a “climate cultist”), and others won’t say anything at all unless it’s positive. By far, the feedback has been mostly good, and that makes me feel good. I feel as if I’ve managed to write something useful about something important. I articulated the situation clearly enough to convey the urgency and concern I feel, and the factual and logical basis for that concern. That apparently resonated well with thousands of readers. Awesome! I feel like I’ve contributed, and that’s a good feeling. I wonder whether it means I should do more climate science blogging, or counter-creationism blogging, or current events blogging. It’s something to ponder… Friday folds are never going to go viral like these other topics…

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16 November 2015

“Making North America,” episode 3: Human

The PBS series NOVA has a new three-part series called “Making North America” that premiered two weeks ago. Hosted by the director of the Smithsonian Institution’s National Museum of Natural History, Kirk Johnson, the series explores 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 have been covering them one by one. Today, we’ll take a look at the final offering, “Human.”

It begins with the Ice Age of the Pleistocene, since that’s apparently when North America was first inoculated with humans. They came from Siberia, but did they (a) climb over the Laurentide Ice Sheet, (b) wait in the great Alaskan vestibule until an ice-free corridor opened up, or (c) use boats to travel down the west coast? Kirk goes ice climbing and finds it difficult, and uses that as a visually striking rhetorical device that option “a” isn’t so likely. Option “b” is presented as the standard academic party line, but that’s a lead in to an emphasis on the preferred hypothesis, “c,” which leads us to the Channel Islands of California, where a 13,000 year old femur is explored as evidence for boat technology existing early on in the human history of North America.

So people somehow got to places like coastal California, and then they moved inland. One thing they found was critters, and part of the episode visits the La Brea tar pits in Los Angeles, and we get a taste of some fun paleontology as well as a hint of the overkill hypothesis for the extirpation/extinction of the Pleistocene megafauna. That leads us to hunting, and to Clovis points, our oldest uncontroversial archaeological evidence of humanity’s presence in North America’s interior. There’s a cool scene where Kirk makes a spearhead and then tests it against hide-covered ballistics gel.

Agriculture and soil are the next topic, presented starting at Mesa Verde, but then it goes off in a “but then the Europeans showed up” kind of way. I was delighted to see David Montgomery, MacArthur fellow and author of Dirt: the Erosion of Civilizations, show up alongside Kirk in a North Carolina tobacco field. They engage in a fun examination of the soil, and I thought it was pretty clever that they put on aprons for a faux cooking show set up, combining ingredients from jars to make soil: sand, silt, clay, organic matter, living critters, and -this caused both of them to laugh- “time” in a bottle.

The depletion of east coast soils was a matter of national security in the early days of the United States of America, and this offered a way to segue into discussing westward expansion, railroads, and the California gold rush. Kirk and a local expert travel into a mine and examine auriferous hydrothermal quartz veins there. They interpret these as the healed scars from earthquakes, which is stretching the point but probably a good approach for the show’s audience, and it’s accompanied by a lovely animation – showing a vein crystallize from the inside, with quartz nucleating on the walls and grow inward, trapping gold flakes along the way. Another cool visualization was of the old school variety: simply comparing “then” and “now” photos of Los Angeles, showing the profusion of oil wells that used to occupy that town. Even today, there are 3000 active wells in L.A. County.

Burning oil makes CO2, and global warming gets a brief mention, but it’s not dwelled on for more than 30 seconds or so. But a more palpable disaster lies waiting in the Pacific Northwest, so it’s off to Washington to examine a ghost forest and tsunami sand deposit. I appreciated the decision to say “a Pacific Ocean plate” instead of “the Juan de Fuca plate,” for the sake of simplicity. It’s an elegant choice that’s technically correct and also intuitive for the nontechnical audience. But matching this good word choice is a bad word choice – I shudder to report that “fault line” gets used at least once.

The episode concludes with a visual recap of the whole series, and a good message that geologists are useful: learning about the past helps us prepare for the future. As we look back in time, or predict what comes next, we can see that no landscape is permanent. I endorse both of those messages wholeheartedly. They encapsulate the sense of participating in the grand sweep of epic events, and this series did a good job of expressing those events.

I’ve been keeping tally with each episode of the gender ratio of the experts interviewed, and this final episode has a ratio of 6 named male experts to 2 named female experts, one of whom also appeared in episode 1. That makes “Human” the most male-skewed episode of the series (previous episodes were 5:2 and 2:2).

The episode airs in two days: on Wednesday, November 18, on your local PBS station. Check it out.

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13 November 2015

Friday fold: chevron-folded chert

Samuele Jæger Papeschi is the source for today’s fold:


Those are:

chevron-folds in radiolarian cherts – Jurassic radiolariti fm. – Quercianella – Leghorn, Italy

Cool. They look a lot like the chevron-folded cherts near San Francisco. Same age, too.

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12 November 2015

Dialing in 5 GPa on a diamond anvil cell

Peek into the middle of this contraption, and tell me if you see anything interesting:


Did you notice the gem-quality diamond in there?


This is not the latest in fashionable jewelry, but a scientific tool called a diamond anvil cell. (Well, half of one, anyhow.)

The exceptional hardness, strength, and clarity of the diamond allows pressure to be cranked up on a sample squeezed between two diamonds, and laser light to heat the sample up, approximating conditions in Earth’s interior. Extraordinary temperatures and pressures can be achieved in such an apparatus. And if you’re an experimental petrologist, you can watch what’s happening through the window of the diamond itself. The two images above show open ones: half of the apparatrus. I got to examine them courtesy of Steve Gramsch of the Carnegie Institution’s Geophysical Laboratory during my visit to the Carnegie a few weeks ago. He then handed a closed diamond anvil cell to me. I hefted it and asked how much pressure it was under. Steve casually replied “60 gigapascals or so.”

That shocked me – not that it could get up that high, but that it was that high, just sitting there at that extraordinary pressure. Suddenly, I felt as if I had a grenade in my hands.

Consider the following:

  • A newton is the force needed to accelerate a mass of 1 kilogram by 1 meter per second per second.
  • A newton of force spread over a square meter of area is one pascal.
  • One billion pascals is one gigapascal (GPa).
  • Setting aside tectonic stresses and only considering overlying rock mass and the acceleration due to the force of gravity, the pressure in Earth’s interior goes up by about 30 megapascals (MPa) per kilometer of additional depth: that’s 0.03 GPa/km.
  • 60 gigapascals is therefore a pressure equivalent to about 2100 kilometers of depth in the planet – most of the way through the mantle, though not quite to the outer core (which is at ~2900 km depth).
  • A pressure cooker cooks at 0.0001 GPa.
  • Your car’s tires are inflated to a pressure of 0.0002 GPa (2 bars, or ~30 psi).
  • 60 GPa is a lot more than 0.0002 Gpa.

Steve brought out two Allen wrenches. I put one in the red Allen bolts (on the left – a dated Cold War reference there) and one in the blue bolts (on the right), and gave each a gentle turn through about 5 degrees of arc. It was easy. I was done in about 8 seconds.


By turning that Allen wrench, I dialed up the pressure on that diamond anvil cell by 5 gigapascals (GPa); that’s 25,000 times the pressure that your tires are under, added to the diamonds’ pre-existing pressure before I walked into the room. The diamonds were now squeezing each other at 65 Gpa. If you accept a pressure gradient of 30 Mpa per kilometer, that means my turn of these four bolts was equivalent to plunging the experimental rock sample another 167 km deeper into the lower mantle – an hour and a half of driving time, if you could drive at highway speed straight down through bridgmanite, (which of course you cannot, Aaron Eckhart’s and Hilary Swank’s best efforts aside).

That blew my mind. It was such a small motion on my part, imparting so little force to the Allen bolts, but that translated into a mighty change on the tip of that diamond.

Our campus’s geology club is having Dr. Gramsch out to speak about mineral physics tomorrow – and I think these diamond anvil cells will be props in his lecture. I hope dearly for my students to be similarly impressed at this tiny little microcosm of our planet’s deep interior.

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9 November 2015

The final days of sub-400 ppm carbon dioxide

Here are the last two years of measurements at the Mauna Loa CO2 sampling station:


In this graph, you can see that the annual minimum concentration of CO2 occurs in September (at the end of the boreal summer, when northern hemisphere trees wrap up their five months of carbon draw-down), and the maximum comes in May (as boreal summer begins and the photosynthesis fires up again). The big green number up top is yesterday’s measurement: 399.65 parts per million of our atmosphere are carbon dioxide.

During the Pleistocene “ice age,” this measurement (or its glacial air bubble proxy) varied between 180 and 280 ppm. It was at about 280 ppm prior to the Industrial Revolution. Since then, we’ve been taking carbon out of the ground, where it was sequestered hundreds of millions of years ago, and setting it on fire. The “free” energy we got from this chemical reaction has powered tremendous advancements in well-being of most humans living in industrialized societies. But the oxidation of carbon results in carbon dioxide, and though plants suck some of it up again, and the oceans absorb about a third of it, most continues to hang out in the atmosphere. Over the past two centuries, it has been piling up like dishes in a dormitory sink. This waste gas is a problem, for it’s selectively opaque to light – visible light is unfiltered by CO2, but CO2 blocks infrared wavelengths, the kind any object sitting in the sun emits long after the sun has set. That means our atmosphere retains more of the heat that would otherwise get bled off into space. Energy comes in more or less constantly from the sun, but less and less of it is making it back out.

Lockwood DeWitt called my attention today to the fact that this week is probably the last time you or me or anyone now alive on planet Earth will ever see concentrations of CO2 lower than 400 ppm. Ralph Keeling published a short piece about it, here. Unless something fundamentally changes in our relationship with the atmosphere (such as developing and deploying effective artificial carbon sequestration), the gas’s long-term accumulation will keep rising, and the planet will keep hanging on to a little more heat than it used to the year before. Though “400” is simply a round number with no inherent particular significance in and of itself, passing it for good seems a valid enough reason to pause for a moment and reflect on this massive thing we’re doing to our planet. Every additional increment of CO2 is likely to be a moderately long lived addition to our atmosphere. Its heat-trapping capacity is a major force driving our climate system into new, uncharted terrain for a long time to come. We depend on our climate. People we will never meet on the other side of the world do, too. Our children will depend on it. Grasshoppers and bluebirds and rattlesnakes and whales depend on it. Fungi depend on it. Grasses depend on it. Coccolithophores depend on it. And though this should be obvious, I’ll go ahead and say it explicitly: to a greater or lesser extent, we depend on them. Everything’s interdependent. We all live downstream – and we’re polluting that stream.

This planet is changing, and in many ways the changed Earth won’t be as hospitable to a lot of us who evolved in more stable times. The changed planet won’t be as comfortable for a lot of our neighbors, a lot of people we will never meet, not to mention non-human animals large, small, familiar, exotic, ecologically negligible, or ecologically essential. As a friendly reminder, if we screw the whole system up, we have limited real estate options:

earthImage modified from an original by NASA, here

We are beyond overdue in addressing this. A smart society would drive fossil fuels to extinction. We need to ramp up carbon-free sources of energy immediately and make them the cheaper economic choice by taxing the hell out of carbon power (coal, oil, and natural gas), and using that money to incentivize non-carbon energy sources instead. Our society has to set up a new system where it’s easy for people of limited means to eschew carbon. We are behaving stupidly by failing to deal with this problem, by continuing to reward those corporations which pursue their own profits (their only reason for existing) by damaging the world the rest of us live in. Given what we know about the Earth system’s physical components and the way they exchange energy, it is insane that we are letting this pro-carbon incentivization continue. Collectively, we are fouling our nest, and there are no other nests.

You may have come of age in a world where global carbon dioxide concentrations were less than 400 parts out of every million, but you don’t live in that world now, and you never will, ever again. What are you going to do about that? How high will you and I let this number climb?

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6 November 2015

“Making North America,” episode 2: Life

The PBS series NOVA has a new three-part series called “Making North America” that premiered last week. 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’m covering them one by one.

Episode 2 is about paleontology, and the extraordinary natural heritage of our continent’s fossils. This is a topic near and dear to the host, a paleobotanist who tweets as @leafdoctor.

The episode begins on the Kaiparowits Plateau in Utah, where Kirk begins with the general public’s favorite fossils, dinosaurs. He points out North America’s rich dinosaur heritage, and asks why it might be so diverse. That guiding question takes viewers to the Bahamas, where Kirk scuba dives to examine stromatolites in the tidal current-scoured channels where they persist despite the attempts of corals and seaweed to colonize their exteriors. I appreciated the program referring to the microbes that built up the stromatolites as bacteria rather than “algae,” as is often the case in public-interest programs like this. In a related segment, Kirk and a local expert wade into a shallow lake to examine in situ microbial mats, which they examine in hand and say resembles “nasty black lasagna.”

The stromatolites of course pumped out a bunch of waste gas, and that totally transformed the world (sound familiar, Industrialized humans?). That sets the stage for the future evolution of animals. So then we go to Kansas, and visit Monument Rocks, a place I visited with Ron Schott when he made the GigaPan that’s one of many featured in the new “Explore North America” virtual experience on the NOVA website. (I have one that’s included in the collection, too!) There, the paleogeography of North America during the Cretaceous is explored, though the word “Cretaceous” only slips in once by my count. Then, the Western Interior Seaway divided the continent into two isolated landmasses, each with its own unique dinosaur evolutionary trajectory.

In the badlands of North Dakota, Kirk examines the K/Pg boundary by digging up the boundary layer, and showing in the field with a small microscope the little impact spherules (tektites) that rained down in North Dakota due to the Chicxulub impact. This was pretty cool – I’ve seen that layer in that same formation (the Hell Creek Fm.) but hadn’t seen the spherules.

There’s a nice graphic where Kirk and colleague look at a cliff where the Z Coal (base of the Hell Creek) is exposed, and below it, the magic of computer animation draws in dinosaurs, and above it, other animals, but no dinos (other than a duck). It’s a nice composition – combining stratigraphy with a cartoon sketch.

The extinction of the dinosaurs leads to the rise of mammals, and footage of Kirk in a lemur sanctuary feeds into an examination of why there are so few native primates on North America before people: ancient climate change led to ecological turnover and a drier, grassland dominated ecosystem, which was rough on the arboreal primates. That changed when people invaded, and that sets the stage for Episode 3 of the series.

In all, it was a grand sweep, and I felt the narrative arc was more fully expressed than in Episode 1.

The gender balance wasn’t as balanced in this episode, though: of the named experts, five were men and two were women.

Episode 2 airs on November 11. Check your local PBS station for times.

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