12 February 2020

History of Science: Antiquity to 1700, by Lawrence Principe

My most recent commuting audio has been this course from The Great Courses: Johns Hopkins professor Lawrence Principe‘s History of Science: Antiquity to 1700. I checked it out from my local library: 36 lectures, each about 30 to 45 minutes long. I found it quite interesting, well-paced, and insightful. Principe is an organic chemist-turned-historian-of-science, and he recounts key developments in the way people thought about “natural philosophy” (it wasn’t dubbed “science” until centuries after people starting doing it). Alchemy, astronomy, and physics are the key foci; biology gets a series of cameos but is really not a star. There’s pretty much no geology in it at all. Regardless of discipline, the key thing about this course is that Principe is very keen on trying to shuck modern scientific conventions in reviewing the thinking of historical practitioners. In other words, his goal is to anchor scientific advances and thinking of the past strictly in the context of the time: the religious, societal, technological, and political milieu that nurtured (or permitted, or resisted) new ideas. I appreciated Principe’s style as a lecturer, and was impressed with his mastery of such a wide span of practitioners, set in Europe, North Africa, and the Middle East over the past several thousand years. Quite enjoyable; I look forward to listening to the sequel, about science since 1700.

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10 February 2020

The Pentagon’s Brain, by Annie Jacobsen

This book is a comprehensive account of everything unclassified that DARPA and its predecessor ARPA, has ever done. The subtitle is: “An Uncensored History of DARPA, America’s Top-Secret Military Research Agency.” It begins with testing nuclear bombs at Bikini Atoll in 1954, where theoretical calculations about the Castle Bravo bomb’s explosive yield get a sobering reality check: it was more than twice as powerful as had been anticipated! Oops. The narrative then moves on through time discussing how the U.S. War Department (later rebranded the Department of Defense) pushed research and innovation in military activities. Through the Cold War, groups of scientists and academics collaborate in their attempt to push American military superiority into the future. A significant portion of the book is spent on the Viet Nam War, as this appears to have been a ripe time for out-of-the-box thinking and experimentation with military strategy and technical innovation. Jacobsen also does a terrific job documenting the developments that led to the phenomenon by which I’m communicating this review to you: the Internet, which is a direct spinoff from a DARPA project. Her comprehensive history also devotes substantial attention to the first and second iterations of the Bushes’ Iraq War, with case studies of decisive battles won with the advent of effective night vision capacity, or precisely-guided smartbombs. Biotech also gets substantial attention, especially in the aftermath of 9/11 and the anthrax attacks. A fascinating section on Russian efforts to weaponize some of humanity’s worse plagues makes for chilling reading. The history concludes with a discussion of the modern day, as DARPA explores drones, autonomous robots, cyborgs, and (a perennial topic of fascination for me) artificial intelligence.

Jacobsen’s book is a thorough account of the U.S. interest in science and war. It is very long, which lowers its readability, but increases its scholarly value. The tone is apolitical, but Jacobsen doesn’t shy away from pointing out the unmatched power of these killer innovations. It ends on a foreboding note about the imminent deployment of hunter-killer robots. Will a few top-clearance military scientists underestimate their power in the same way the ferocity of the Castle Bravo nuclear test caught their predecessors by surprise a half century ago?

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7 February 2020

Friday fold: Kings Canyon

Link 2.56 Gpx GigaPan by Ron Schott

I was preparing for my spring break Death Valley field course this week, when I remembered that my friend and colleague Ron Schott had compiled a bunch of useful GigaPans of the sites there. Ron died a year and a half ago, you may recall. I went looking for them on a site he had built,, but the site has now evaporated in the absence of Ron maintaining it. (The Wayback Machine has archived some of its structure, but not its details.) Fortunately, the source imagery itself still exists on the GigaPan website, but it took some serious scrolling to find what I was looking for. Ron made a lot of GigaPans.

That scrolling was not without unexpected surprises, though. I found a 2012 GigaPan he made of our poster session at GSA, and found myself and my then-student (now-colleague) Robin in the image, as well as other geology friends at that meeting. And I found the image above, which is a stunning candidate for a Friday fold. Though I couldn’t ask Ron directly for his permission to use it here, I know he’d have approved.

Here’s what he had to say about it, with some clarifying additions from me:

Marbles of the Boyden Cave Roof Pendant in California’s Sierra Nevada show the results of deformation culminating with batholith emplacement. In addition to the intricate folding displayed here, don’t forget to appreciate the patterns that recent weathering has superimposed on the exposure. This GigaPan highlights the detail of the exquisitely folded marbles. A wider view that establishes a full context of this roadcut can be found here:

Garry Hayes has blogged about the site, and mentions that the folded rock is part of the Kings Terrane, with is Triassic/Jurassic in age.

This image and hundreds of others are part of Ron’s digital legacy, which is lessened through the loss of his own website, but I’m grateful that at least the raw, source imagery remains for us to learn from and be inspired by.

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31 January 2020

Friday fold: tension gashes near Sunflower, Arizona

Reader John Christian shared these folds with me via email last week. They are

quartz veins in slightly metamorphosed Precambrian igneous rocks found near Sunflower, AZ in the Mazatzal Mountains.

The second photo is a close-up shot of the curviest, cleanest batch of folds from the first shot.
These are beautiful examples of folds in similarly oriented quartz veins; we call them “en echelon” for the way you have a bunch of them “marching in formation” w/ the same orientation, and we describe the style of vein as “tension gashes” for their distinctive shapes, with wide middles and tips that rapidly narrow down to nothing. Here’s a similar example from this blog, though not as lovely as the one John sent:

Shearing impacted these rocks in a style of deformation that was simultaneously brittle and ductile. The host rock developed “stretch marks” in the form of these tension gashes, which are after all fractures in the rock, but the rock on either side of the fracture is behaving relatively flexibly, as evidenced by the way these features go from non-existent to a few centimeters wide back down to non-existent again over the distance of only a few 10s of centimeters. The rock “flexed” to allow such a fracture to develop. The fracture was sealed with hydrothermal quartz (bright white due to lots of itty-bitty inclusions of trapped water), making a vein. But deformation didn’t stop then: the two sides of this zone of shearing kept moving, and the quartz veins had to deform to accommodate this differential motion: depending on the portion of the vein you look at, they got stretched, or squashed, or rotated. The overall effect was to take an initial thin “/” shape and bend into into an exaggerated “S” shape.

Let’s add some arrows:

These are really cool structures; Thanks for sharing them with us, John!

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29 January 2020

The Long Way to a Small Angry Planet, by Becky Chambers

Last night, I finished a wonderful little book of science fiction, The Long Way to a Small Angry Planet, by Becky Chambers. It’s the first book in a series of novels, called “Wayfarers” after the name of the ship whose crew are the subjects of the story. Like Joss Whedon’s TV series “Firefly,” the crew of the Wayfarer is motley. Unlike “Firefly,” though, and more like Star Wars, they are a mix of species. This is really cool, because Chambers has a terrific imagination for different species that are part of the Galactic Commons. Alongside humans, there are affectionate reptilian creatures, virus-infected sloth-like creatures that can visualize spacetime better than any other creature, and my favorite, a huge tardigrade-like creature that is the embodiment of peace and caring. Among the humans, there are two frenetic technicians: one who reminds me of Kate McKinnon’s character in the new Ghostbusters reboot, and another who reminds me of Tyrion Lannister from “Game of Thrones.” There’s also the plucky captain who keeps them all together – in my mind, he’d be played by Chris Pratt in a movie version of the book, and a self-aware AI in the ship’s computer mainframe. Over the span of the novel, the actual plot arc is thin, but that’s 100% fine, because this is a book about relationships and personal growth rather than defeating some galactic overlord or somesuch. The chapters are about crises and adventures they have along their way to a job site, a journey that lasts the better part of a year. Each could stand alone as a short story, but the sum of all chapters results in a book that left me feeling like I’d made a bunch of new friends, and feeling very satisfied indeed. Recommended! (And I’m looking forward to starting the sequel next!)

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24 January 2020

Friday fold: Pelham Parkway

Steve Mirsky of Scientific American contributed this week’s Friday fold: it’s in a boulder adjacent to Pelham Parkway in the Bronx, which he spotted while cycling a few weeks ago.

Thanks for sharing, Steve! This is a gneiss find!

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20 January 2020

Book report

It’s been a busy month, and I owe you all some blog posts. Forgive me – my writing energies have been focused elsewhere lately. Now that the semester has started, however, I hope to right that wrong with more regular posting. For now, here’s a four-part book report on recent reading…

The Wizard and the Prophet, by Charles C. Mann

A comparison between two ways of looking at the relationship between humans and the problems of living in the natural world, as exemplified by two scientists, neither of whom I had previously heard of: Norman Borlaug and William Vogt. Mann (author of 1491 and its sequel, 1493) set up Vogt as a plausible font for the modern environmental movement, and the idea that when science teaches us that nature limits populations, we can and should use that insight to trim back our own societal excesses, to live better within our own planetary means. Vogt was worried that humanity was headed for disaster by letting our population grow beyond the planet’s carrying capacity. His 1948 best-selling tract The Road to Survival set forth these ideas and led to the vibrant modern “apocalyptic” strains of environmentalism. Vogt is the titular “prophet.” Borlaug, in contrast, is the engineer who thinks he can fix nature, to bend physical processes to the will of our intention and understanding. Of the two, it seems Borlaug is the better known in the present day, largely through is groundbreaking efforts at breeding disease-resistant strains of wheat. Wheat yields increased by an order of magnitude, and because his wheat was adopted in places like India, Pakistan, and Mexico, the “wizard” Borlaug is credited with saving more than a billion human beings from starvation. He was the spark that lit the Green Revolution; He got a Nobel Peace Prize for this critical work. So Mann’s book is at once a duplex biography of these two men, and also an examination of how their two worldviews take on challenges like clean water, agriculture, and climate change. I found it a thought-provoking volume, though the essential set-up, that there is an irreconcilable dichotomy between their approaches, seems to me a false premise. As author, Mann himself acknowledges this, and doesn’t advocate for one approach or the other. Both wizard and prophet have perspectives we may find useful.

The Living Mountain, by Nan Shepherd

I’ve not been to the Cairngorm Mountains in northeast Scotland, but I feel almost as if I don’t need to. The experience of being in those mountains is conveyed so effectively, so magically, by Nan Shepherd, that actually visiting them in person seems almost superfluous. Very few books that I’ve read achieve this level of place-based wonder, with Arctic Deams (Barry Lopez), Pilgrim at Tinker Creek (Annie Dillard), Desert Solitaire (Ed Abbey), and Refuge (Terry Tempest Williams) being worthy peers. Introspection is blended with natural history in Shepherd’s book, written in the 1940s but only published in the 1970s. The tiny timeless personal adventure of connecting with nature is made manifest through superbly rendered prose. It’s a delectable book, one that sets the pulse of the naturalist to quickening. Really a top notch piece of writing, and I highly recommend it. The version I read had two companion pieces, by Robert Macfarlane and Jeannette Winterson, which really added to the experience. Macfarlane’s piece in particular I thought to be almost as evocative and well-wrought as Shepherd’s book. His essay places The Living Mountain in literary context, and celebrates it as Shepherd herself celebrated the Cairngorms.

All Systems Red, by Martha Wells

A bit of light, fun science fiction. I’m on a kick of reading more sci-fi by women authors, and this was the most recent volume I consumed. What’s distinctive about it is the perspective: it’s told from the point of view of a “murderbot,” a self-aware security droid with some mechanical and some organic components. It (neither he nor she) is assigned to protect a group of scientists prospecting on a new planet, and when things start going wrong, the intensely shy narrator has to cooperate more intensively with its humans than it is really comfortable with. This perspective makes the book worth reading, more than the actual arc of the story: the mystery and drama and whatnot. Rather than getting cozy with these humans, the murderbot would prefer to darken its faceplate and watch hours of illegally downloaded television programs. But when push comes to shove, the nameless narrator invents some clever tricks. It is sarcastic and cynical, a great personality that keeps the writing fresh. As with Annalee Newitz’s Autonomous, a real delight to me was to read what author Wells imagined it must be like for a robot to communicate with other computers from the inside, a distinctly non-human way of interacting with the non-human world.

California Earthquakes, by Carl-Henry Geschwind

A meticulous history of the societal, economic, and political ramifications of living in the Golden State astride a transform plate boundary. I read this volume because the author is a fellow member of the Geological Society of Washington, and I’ve been very impressed through the years of his thoughtful insights about both science presented at our meetings as well as the behind-the-scenes management of the organization. Seeing his volume referenced in Susan Hough’s Predicting the Unpredictable: The Tumultuous Science of Earthquake Prediction gave me the shot in the arm I needed to track down a copy, and read it. It reads like a dissertation, but I don’t mean that in a bad way. Geschwind simultaneously demonstrates an extraordinary amount of research accomplished as well a mastery of synthesizing it into a story that progresses through time. It was originally published in 2001, so reading it today, I felt that the story was incomplete. I’d love to see a follow-up work that covers changes in the way Californians perceive and plan for earthquakes in the past two decades. Writers like Susan Hough cover this terrain well, and that’s where I’ll steer my own further reading on this topic.

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1 January 2020

2019 Yard List

New year’s day! For this blog and me, the first day of the year is time for the annual recap of birds seen on my land in Fort Valley, Virginia. Here are the previous iterations:

This year’s list (biggest year yet!), in chronological order of first sighting:

  1. Pileated woodpecker
  2. Tufted titmouse
  3. Red-tailed hawk
  4. American goldfinch
  5. White-breasted nuthatch
  6. Red-bellied woodpecker
  7. Mourning dove
  8. Carolina wren
  9. Yellow-bellied sapsucker
  10. Chickadee
  11. Dark-eyed junco
  12. Downy woodpecker
  13. Hermit thrush
  14. Brown creeper
  15. Raven
  16. Turkey vulture
  17. Golden-crowned kinglet
  18. Purple finch
  19. Pine siskin
  20. Wild turkey
  21. Eastern phoebe
  22. American crow
  23. Sharp-shinned hawk
  24. Pine warbler
  25. Eastern bluebird
  26. American robin
  27. Whippoorwill
  28. Brown-headed cowbird
  29. Flicker
  30. Chipping sparrow
  31. Northern cardinal
  32. Harrier
  33. Blue-headed vireo
  34. Blue-gray gnatcatcher
  35. Ruby-throated hummingbird
  36. Red-eyed vireo
  37. Canada geese
  38. Broad-winged hawk
  39. Yellow-rumped warbler
  40. Ruby-crowned kinglet
  41. Ovenbird
  42. Bald eagle
  43. Fish crow
  44. Worm-eating warbler
  45. Scarlet tanager
  46. Barred owl
  47. Black-throated green warbler
  48. Great crested flycatcher
  49. Yellow-billed cuckoo
  50. Osprey
  51. American redstart
  52. Great blue heron
  53. Spotted towhee
  54. Wood thrush
  55. Black and white warbler
  56. Rose-breasted grosbeak
  57. Black vulture
  58. Brown thrasher
  59. Eastern wood-pewee
  60. Chimney swift
  61. Great horned owl
  62. Chestnut-sided warbler
  63. Blue jay
  64. White-throated sparrow
  65. Winter wren
  66. Swainson’s thrush
  67. Sandhill cranes (!!!)

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13 December 2019

Friday fold: blueschist & eclogite at Jenner, California

Here’s your Friday fold:

Let me explain. Like ~25,000 of you, I spent much of the past week in San Francisco, at the AGU Fall Meeting.

I headed out one day early, to capitalize on an opportunity to take a trip up to Jenner, California, to check out some cool metamorphic rocks on the coast there. My guide was Dexter Perkins, mineralogist and petrologist of the University of North Dakota. Dexter drove me up to the right place, but the weather wasn’t really cooperating:

Oh well, we’d come all this way: I guess we were going to get wet.

The resistant protrusions you see along the coast at Jenner poke out of the sand as well as the surface, and showcase truly wonderful rocks. Here’s a view of one of these outcrops, sticking out of the sand where the Russian River flows into the Pacific. Note also the birds (white things in the background): approximately the same number here as there were geophysicists at the Moscone Center a couple of days later!

This particular boulder is a relatively low-grade meta-basalt: it’s been altered to greenstone, but still preserves some primary igneous features. Here are two examples of well-preserved lava pillows in the greenschist-facies boulder:

There was more to be seen here, but we weren’t able to get to all the good stuff. For instance, this boulder of what appears to be mixed metamafic (green) and metapelitic (gray) mélange:

We couldn’t get to it because it was not quite low tide. The Russian River was thus backed up and covered in flotsam. That didn’t stop Dexter from trying to balance on floating logs to get to it (without success):

The muddy cliffs appeared to be dominated by metasedimentary mélange, with clear lozenges of graywacke in what appeared to be a shaley matrix. Here’s a chunk of the sandstone:

But the real attraction of the outcrops at Jenner are the high-grade subduction-related metamorphic rocks: blueschist and eclogite. Unfortunately, all my photos of these lovely rocks are sopping wet, leading to a lot of glossy glare… Still, the colors are something else:

Blueschist, as the name implies, is blue. The rock is blue because it has blue minerals in it: glaucophane and lawsonite. It’s a meta-basalt that recrystallized at high pressure but relatively low temperature. Because rocks are relatively poor conductors of heat, lithosphere can be subducted at a rate faster than it can thermally equilibrate to surrounding warm rock. This gives subduction zones a unique metamorphic signature: high pressure and low temperature are the conditions you need to get ~200° to ~500° C and depths of ~15 to ~30 km. Eclogites are meta-basalts, too, but they have been even further “down the subduction hatch:” perhaps ~45 to 60 km depth) with temperatures of 400° to 1,000° C. They have their own distinct color scheme: like a Christmas tree, with red garnet and green omphacite.

You can see both at Jenner, which is just about mind-blowing: that these rocks have been SO FAR down into the planet, and yet somehow, in spite of their density, made it back to the surface where lucky Subduction Pilgrims like myself could visit them and get to know them.

Here’s a diagram my colleague Christie Rowe drew up to explain blueschists for a stop on our new digital field guide to the geology of Angel Island, part of the Streetcar 2 Subduction project that we launched at Fall Meeting:

There’s really no precise cut-off between the two metamorphic facies, since the presence or absence of water will have a critical role in determining whether metamorphic reactions can proceed efficiently.

The blueschists at Jenner are unique in my experience, because they feature quite a lot of garnet.

This garnet’s presence in the blueschist is cited as evidence that these rocks were once all eclogite, and then some of them retrograde-metamorphosed to blueschist on their way back up to the surface.

Layering of blueschist layers relative to greenschist layers was a key feature of one boulder:

These cm-scale stripes are a little surprising – it’s not as if the green slices have been down to eclogite-inducing depths, but the blue ones haven’t. Something else is controlling the situation here, probably water, perhaps percolating along fractures in the meta-basalt.

It was in this one that the fold (that started this post) appeared:

I resolve to get back to Jenner when the weather’s more conducive to careful study of these intriguing rocks.

In the meantime, the AGU Fall Meeting was a big success, and I look forward to next year’s gathering, as well as the associated field trips! Happy weekend to you, and if you’re still in San Francisco, have a safe journey back home.

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10 December 2019

‘Streetcar 2 Subduction’ is live!

This week marks the launch of a project I’ve been working on for a year and a half: “Streetcar 2 Subduction,” a revision of Clyde Wahrhaftig’s classic field guide to the geology of the San Francisco Bay area. Working with Jamie Kirkpatrick of McGill University (the project’s leader) as well as Christie Rowe (also from McGill), Kim Blisniuk of San Jose State University, and John Wakabayashi of Cal State Fresno, we used brand-new content creation tools in the web-browser-based version of Google Earth to make a series of digital field guides.

These field guides are combinations of Google Earth, Google Maps Streetview, photographs, diagrams, and video, with links out to additional resources in the textual description of each site. Google allowed our team early access to the tools, which allowed us to build the trips over the past six months as “trusted testers” and launch the revised guide only a week and a half after Google released the content creation tools to the public. We greatly appreciate their trust, and are quite pleased with a blog post they wrote and published yesterday about the project.

You can access the trips on a laptop via the Chrome browser, or you can use them in the field with your smartphone and the Google Earth app.

AGU supported the revision effort with Centennial funding, and also tasked AGU staff with assisting: Brandon Bobosink was the project manager, Jenny Lund did editing, and Derek Sollosi edited our videos. Each made valuable contributions to the project, and the scientists on the project are very grateful for their expertise. Our goal was to separate wheat from chaff, and to update the science, and most importantly to make the rich geological history of the Bay area more accessible to more people.

The launch coincides with a bunch of anniversaries:

  • the 100th birthday of AGU
  • the 100th birthday of Clyde Wahrhaftig
  • the 35th anniversary of the publication of the original guide

We’ve released 7 trips at this point, with another 3 due out next month. Each trip has between 2 and 30 sites where geological insights can be gained: vistas and outcrops, rocks and structures, landforms and history. The trips are all free, and will continue to be so in perpetuity. AGU has also made a PDF of the original guide available to commemorate the revision.

Here is a link to the landing page for the project, with links (under “Streetcar trips”) to the various digital field guides: Because that is a very long URL, we also made this short one for easier sharing:

To promote the launch of the guide, our team led two field trips on Sunday, one north to look at Franciscan complex rocks related to Mesozoic subduction, and another south to look at deformation along the traces of the San Andreas Fault and the Hayward Fault. Here’s the active tectonics trip posing in front of a sag pond developed along a right step in the right-lateral San Andreas Fault:

More than a hundred people participated in the two trips! We feel really good about that.

If you’re at the AGU Fall Meeting today, there are several Streetcar related activities:

Eos ran an article about the project a few days ago: and that’s a good place to learn some of the basics if you’re curious. They also published a rembrance of Clyde Wahrhaftig, the original Streetcar author here:

A piece on the project aired on the local ABC news affiliate last night:, in which Christie does a great job explaining our motivations, and the reporter, Liz Kreutz, does a great job walking people through how to use it.

KQED science also featured the project in a brief piece here:

More press soon, I hope… 🙂

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