23 March 2018
We’ve had a lot of time off from work and school this week thanks to a late-winter snowstorm.
There have been some fun examples of post-snowfall deformation that resulted. Here’s one from my kid’s playground slide:
I posted this on Twitter the other day because it reminded me so much of a detachment fault, a big slab of snow detaching and sliding downhill under the influence of gravity. I like the little tear faults along the edges, too.
Brian wrote this one up on his (now hibernating) blog:
Snow is so great — not only for getting unexpected days off from work, but also for these serendipitous analogue deformation experiments.
Have a happy Friday all!
16 March 2018
Today’s Friday fold comes to your eyeballs courtesy of my colleague Shelley Jaye, who took it in 1982:
She found this in a glacial moraine adjacent to Lovlibreen Glacier, on the north shore of St. Jonsfjorden, Spitsbergen, Svalbard. Very cool disharmonic folding.
Thanks for sharing, Shelley! Happy Friday to all.
14 March 2018
New media to show off exemplary features of the Devonian-aged Hampshire Formation along Corridor H, West Virginia
Last week, I was in Morgantown, West Virginia, to deliver a colloquium talk to the geology department at West Virginia University of geological visualization. The next day, I took some time on the way home to geologize a bit on the road called Corridor H, a gorgeous transect through the eastern Allegheny Plateau and western Valley & Ridge provinces. I focused that day on the Hampshire Formation, Foreknobs Formation, and Tonoloway Formation. Among these, the Hampshire is the most recent. It’s a series of river channel sandstones and their associated floodplain muds. It is bright red in color, indicating its deposition under highly oxidizing conditions; it’s a classic set of “red beds.”
Many of the roadcuts on Corridor H show insightful cross-sectional views of some of these channels:
Here’s a GigaPan I made there (viewed through the lens of the superlative GIGAmacro imagery viewer):
These sandstones and red shales used to be sand and mud back in the Devonian period of geologic time. That sand and mud didn’t magically spring into existence, materializing from thin air. Instead, it materialized from a thick mountain range. This was the time of the Acadian Orogeny, a mountain-building event accompanying the accretion of a microcontinent. In this modification of one of Ron Blakey’s excellent paleogeographic maps, I show with red arrows the sediment transport that would have transpired as the Hampshire Formation was being deposited:
It’s “molasse,” the terrestrial siliciclastic signature of an orogeny.
The Hampshire has some truly excellent primary sedimentary structures that were formed during the time its sediments were deposited. For example, check out these “ball & pillow” loading structures, as a heavy load of wet sand was suddenly laid down on top of some squishy wet mud. The sand sagged down, and the mud squirted up between lobes of descending sand, making flame structures.
Here’s a 3D model of it:
I also found this excellent example of a congruent primary sedimentary structure. This slab (upside-down) shows flute casts, the sand-filled-in declivities excavated by scouring currents into an underlying (pre-existing) mud deposit. This hollowed out tongue-shaped grooves, deepest upstream and then flaring out and shallowing in the downstream direction. After the scouring was completed, sand came in and filled in the hollows.
Looking obliquely across the downstream (to the right) current:
Here is a 3D model I made of this slab:
The Hampshire is a favorite of mine on Corridor H. It tells a beautiful, consistent tale, one with big-picture tectonic importance, but also one accentuated with fine details.
13 March 2018
This fascinating new work by ornithologist Richard Prum re-examines sexual selection (mate choice) as a driving force of evolutionary change independent of (and sometimes in contradiction to) the mechanism of natural selection (environmental adaptation). Prum positions himself as a modern advocate for the ideas Charles Darwin expressed in The Descent of Man, and that Alfred Russel Wallace argued against in the years following Darwin’s death. In The Evolution of Beauty, Prum claims that most modern evolutionary biologists are “neo-Wallaceans” in that they view sexual selection as only a superficial proxy for fitness as determined by natural selection. He argues passionately against this idea, and goes to great lengths to show how some of the birds he has studied are exemplars of a different evolutionary logic at work. He calls this the “Beauty Happens” hypothesis, and he makes an excellent case for it. Delving into lekking behavior in manakins, the showy architectural constructions of the bowerbird, the reproductive plumbing of ducks, or the plumage of the great Argus pheasant, he communicates both his interest in the details of bird lives, but also in how these natural historical studies reveal information that stands at odds to an evolution that is exclusively based on natural selection alone. Sexiness matters, Prum argues – for its own sake, separate from serving as an indicator of fitness. In several concluding chapters, he applies lessons learned from the world of birds to humans, with some interesting insights for the behavior and anatomy of our own species. It’s well written, relevant, and insightful. I enjoyed reading it.
9 March 2018
Arizona State University’s Steve Semken is the source of this week’s guest Friday fold:
The fold here is an insider’s view of the Raplee Monocline, as viewed from a raft on the San Juan River in Utah. Steve describes it as
Beloved of geology textbook publishers everywhere.
Though monoclines out west are usually huge features (and thus hard to fit in a single photo unless you’re in an airplane), this is a nice image because it clearly shows the strata at different angles of dip on different portions of the structure. Thanks for sharing, Steve!
1 March 2018
As noted previously, the old way of viewing gigapixel imagery is no more. But there is a new, better way. The GIGAmacro company has a better viewing platform that can be used either with images uploaded to their server or with pre-existing images that currently “live” at GigaPan.com.
Here’s an example: a roadcut of limestone of the Grudaidh Formation (Durness Group) in the Northwest Highlands of Scotland, near Ardvreck Castle, showing several vogesite sills (igneous intrusions parallel to bedding) and faults that cut through the beds and the sills:
Note that there is a dynamic scale bar in the lower right. Watch it change as you zoom in. I calibrated this scale on the 1-cm scale markers on the side of the mechanical pencil that I have used in this image as a sense of scale (see if you can find it!). You’ll also note that the annotations are dynamic: the thickness of the lines (tracing the sill contacts in yellow, the fault trace in red) stays constant over various levels of zoom, and you can turn them on and off with the control panel at the right. Use the measurement tool to measure the thickness of the beds, or the offset on the fault. You can even rotate the whole gigapixel image with the rotate button at lower right – restore the layers to their original horizontal orientation; and read off the apparent dip from the slider bar.
Isn’t this cool? Yes! The correct answer is this is very cool indeed.
26 February 2018
The authors of this essential study are both scholars at Harvard University. They specialize in studying the decay of democratic governments and societies, one in century-ago Europe, and the other in half-century-ago years ago Latin America. They spell out the structure of authoritarian takeover across these different contexts, and then turn to our situation in 21st century America. This book could not be more timely, more relevant, or more essential. I implore you to consume it.
Republicans: read it.
Democrats: read it.
Americans: read. it.
Four key indicators of potential authoritarian behavior in national leaders are spelled out, and examples are given of each from various regimes in various countries over the past 100 years. They are: (1) rejection of (or weak commitment to) democratic rules of the game, (2) denial of the legitimacy of political opponents, (3) toleration of or encouragement of violence, and (4) readiness to curtail civil liberties of opponents including the media. If a leader, including a democratically elected one, shows any one of them, they can potentially transition to autocracy.
How many of these has Trump engaged in? Shockingly: all four. Quantitatively and qualitatively, Ziblatt and Levitsky document his authoritarian tendencies. Only the strength of the nation’s democratic institutions, both formal and unwritten norms, can keep the government on track. The authors show numerous cases during the administrations of Roosevelt, Lincoln, Jackson, and Nixon when checks and balances and adherence to norms helped tamp down Presidential authoritarianism (of both parties). Unfortunately, American democracy has been weakened seriously over the past thirty years. Trump entered the Presidency when American governance is more susceptible to authoritarianism than any time since the McCarthy era. The pump has been primed.
Significant discussion is given over to delving into two particular unwritten norms that serve to stabilize American governance: those of mutual tolerance and institutional forbearance. Mutual tolerance means seeing opponents as people, as citizens with rights the same as your own. When you start viewing your political opponents as traitors, when opponents have become enemies instead, mutual tolerance has broken down.
Institutional forbearance means not using all the tools that you can technically, legally use. For instance, the filibuster has traditionally been a weapon of last resort in Congressional deliberations, used rarely. The authors document the increase in its frequency through time. Similarly, threatening/forcing government shutdowns and other forms of brinksmanship have become standard tools, despite their brutal collateral effects on the country and its economy. These tools were once kept in reserve, but they are now deployed regularly. The standard has changed. The situation that transpired in the last year of Obama’s presidency, with the opening of a seat on the Supreme Court and Congress’s subsequent refusal to consider any Obama nominee, was an unprecedented example of the national change in standards of institutional forbearance. North Carolina’s (Republican) legislature’s emergency session to change the powers of the governor prior to the swearing in of a new (Democratic) governor is another example of how actions once considered outrageous are now seen as feasible.
How did we get to this point? Levitsky and Ziblatt document how Newt Gingrich initiated a new GOP culture of demonization of Democratic opponents, using adjectives like “sick” and “treasonous” to describe their behavior. Starting in the latest 1970s, but reaching its culmination during the mid-1990s, Gingrich’s reorganization of Congressional behavior inoculated a new culture into the Republican party, a take-no-prisoners attitude that was egged on and enabled by conservative media outlets, Fox News in particular. As Republicans stopped cooperating with Democrats, the Democrats had to respond. Did they continue to operate by the traditional rules of conduct (which had now been rendered ineffective) or did they respond to the new landscape by breaking some norms of their own? President Obama’s reliance on executive orders was a departure from the traditional way of doing things, but with such a hostile, recalcitrant Congress, it’s not clear he had too many other options if he wanted to have any kind of record of accomplishments. Norm breaking begets reactive norm breaking. The whole system has shifted into a new, less cooperative state of operation.
Thus Ziblatt and Levitsky demonstrate that the current toxic political landscape is a fallout from a GOP lurch to the right. We are polarized, but asymmetrically, and the trigger was pulled by Republicans. But Ziblatt and Levitsky aren’t focused on finger-pointing, merely explaining how the landscape we inhabit came to be. Over the past two decades, animosity has been accentuated, and we find ourselves in a time when a sitting U.S. president uses bullying and name-calling, threatens opponents with prison, praises white supremacists, and demonizes the media. This is just his “in-house, on the job” behavior; it doesn’t even touch the unsettling possibility of Trump’s coordination with a hostile foreign power (Russia) or his crass, unfaithful, dismayingly sexist, disrespectful personal behavior. This is the world we inhabit.
If we want to preserve the American system of governance, citizens and representatives of all parties need to demand adherence to mutual toleration and a commitment to seeing their opponents as legitimate fellow citizens. The first step is probably for you to read this book.
23 February 2018
In preparing last week’s Friday fold, I did some browsing around in Google Earth in northwestern Namibia, at the intersection between the Kaoko and Damara deformational belts. Man, it’s incredible there. Check out some of the folds you can see from space:
… and zooming in some more; Really, this is just spectacular:
Check it out for yourself on Google Maps. Happy Friday to you!
21 February 2018
Trevor Noah is a South African stand-up comedian who rocketed into American awareness when he was selected as the successor to Jon Stewart as the host of Comedy Central’s news program The Daily Show. This book is Noah’s autobiography of growing up in South Africa, at first under apartheid, and then in the new post-apartheid era. It is the best account I’ve read of the institutional and cultural structure of that country’s unique form of institutionalized racism. It’s also a powerful insight into the attendant sexism, something that will unfortunately be recognizable to modern readers in the United States. Noah was raised by his mother, at first independently of his distant father, and then in the same house as an abusive stepfather. Noah’s father is white, and his mother is black, which makes him “colored” in the South African racial classification scheme. In many of the book’s anecdotes, the question of what to do with the multilingual colored boy provides the dramatic impetus. That apartheid existed in my lifetime strikes me as a horrific curiosity; we are not far removed from this police state. Its racial legacy is on plain display to anyone visiting modern South Africa, which is still starkly divided by race and economic comfort. The shantytowns you see lining the highway as you drive from the airport to Cape Town stand in stark contrast to the armored compounds in which the rich of Johannesburg luxuriate. Noah is a gifted story teller, and though there’s plenty of humor to be found in these pages, it’s not the focus. He presents a clear, thoughtful articulation of the bizarre society of apartheid South Africa. Some of his insights are brilliant distillations of the psychology of extraordinary situations: how groups treat outsiders, the motivations of the impoverished, and regular old teenage romantic angst. I think it’s particularly useful in the context of the Trumpocene epoch in America, when I fear there’s a similar mistrust between societal groups developing, similar ferocity of racial animus, a similar dismissal of women’s reports of abuse, and a similar imbalance between who has all the guns. I was struck while reading it of the parallels to the country and time I live in. It wasn’t an alternate universe I was reading about, it was a cautionary tale of direct relevance. Recommended.
16 February 2018
Today we get to look at some spectacular folds from Namibia’s Zerrissene turbidite system, courtesy of my friend Jay Kaufman of the University of Maryland, College Park. He scanned some of his old slides to share some on-the-ground visions of this incredible place with us:
That’s an overturned syncline. The upper left limb of that fold has been tectonically flipped over. The characteristic features of deformation in this area is the westward-vergence of the folds and the thinning of the upright limbs of the folds (bottom right in all four of these images). The view in all these photos is roughly toward the south.
Note the parasitic small-scale folds in the core of this one:
(Also, did you catch the small-offset ~vertical fault at lower left?)
Thanks for sharing, Jay – these are awesome!