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!
15 February 2018
The Octopus, the Sea, and the Deep Origins of Consciousness is the subtitle of this fascinating, extremely approachable book. Paraphrasing Thomas Nagle, it asks “What is it like to be an octopus?” The author is a philosopher by training, but he does a fantastic job as a science writer, too. Anecdotes about encounters with cephalopods while diving are mixed with careful, deliberate, dejargonized descriptions of the scientific studies that have illuminated the evolution of minds. While we know that dolphins and chimpanzees and parrots are smart, they are all united in being vertebrates with a similarly-organized nervous system. Cuttlefish, squid, and octopuses are however much more distantly related (we share a common ancestor something like 550-600 million years ago), and yet they have independently evolved a remarkable intelligence. Like us, they have large nervous system and camera-like eyes, and they play, solve puzzles, and are able to recognize specific individuals (both among octopuses and humans). Unlike us, they have almost no skeletal material, most of their neurons are in their tentacles (essentially, “eight large, flexible lips”), and what amounts to a brain is roughly donut-shaped and has their digestive system pass straight through its middle! They are weird – as alien a natural being as we are likely to ever encounter.
Godfrey-Smith describes the evolution of minds from the very earliest signalling behavior in bacteria, drawing from molecular genetics, developmental biology, ethology, and paleontology. He spends a delicious chapter among the Ediacara fauna en route. In plain terms, he illuminates what a nervous system is good for. He reveals that which is hiding in plain sight: that our nervous systems can partially operate independently of direction from our brains, and argues that octopus tentacles may well be said to “think” for themselves. He dives deep into the remarkable color/texture manipulation of the skin in these cephalopods, and the evolutionary pressures that led to their woefully short lifespans (most octopuses are dead by two years of age). He explores the possible beginnings of octopus culture at a site off the coast of Australia, and speculates how unusual social living might drive octopus mind evolution in new directions. All told, I found it to be a heartfelt, insightful book.
13 February 2018
My field assistant sidles up to an outcrop showing a scaly texture:
This is outside of Camerino, Italy, in the central Apennines, on a small road near Morro. The outcrop here is adjacent to an old hermitage. The limestones here are early Cenozoic, probably the Scaglia Variegata, and they have been thrust up and over Miocene-aged turbidites that floor the Camerino Basin. The scaly pattern in the outcrop behind my son is a nice example of a distributed S-C fabric: two foliation surfaces which form in many rocks subjected to shearing stresses. The direction these structures “lean over” reveals the kinematics that formed them (left/west over right/east). Here’s a detail, followed by an annotated copy:
This thrusting was the process that built the Apennines up into a gnarly mountain range, but they were followed in time and space by a series of extensional faults, like those responsible for the recent devastating earthquakes in the region.
A few more shots showing these lens- to lozenge- to sigmoidal-shaped blebs of limestone:
Though the limestones are early Cenozoic in their depositional age, the structural fabric here was imposed later, probably in the Miocene, contemporaneous with the turbidites that fill the basin to the east.
12 February 2018
In the epilogue to 11/22/63, Stephen King’s time-travel novel, he made an explicit point to laud Time and Again by Jack Finney as “the” time travel novel. I figured I should check it out. Here’s my report. This is a book that was written in the late 1960s, and feels like it. The writing is fine, with a particular strength being its rich, detailed descriptions. The social mores it assumes, however, don’t stand the test of time (I know, the irony, right?). There’s an off-puttingly substantial ration of casual sexism. But that’s in no way the focus of the book; just a filter through which the story is presented. The basic plot is that an artist from an advertising company on Madison Avenue is recruited by a secret military project to go back in time to 1882 New York City, and see if his presence there alters the future. The actual mechanism of the time travel is surprisingly non-specific, but basically seems to rely on the protagonist’s mental state (manipulated by self-hypnosis) in conjunction with a particular building on Central Park West. The world he visits lacks cars, but is rich in horses. It is non-egalitarian, but also full of spark and hope. There are some aspects of New York which remain constant between the two times, and others that are radically different. There is a romance that ensues, and the protagonist must ultimately make a choice as to when he wants to be. One interesting quirk is that it’s substantially illustrated with period sketches and photos, presented as if they were made by characters in the novel. This lends the book an authentic, documentary-type feel. There are several twists and turns along the way, and these are satisfying to a modern reader. As a novel, it’s fine, I reckon. Nothing too amazing (I liked 11/22/63 better), but I liked the unexpected, decisive conclusion.
9 February 2018
Brian Yanites of Indiana University is the source for today’s Friday fold:
Zooming in on the outcrop:
Brian tells me that this is
~10 km west of the earthquake(s) in Taiwan this week. These are interbedded marble/schist and gneiss (was across river and location is really messed up geologically). Photos were taken along the Shakadang Trail in Taroko Gorge National Park. Beyssac, et al. (2007) found Zircon He ages from these rocks to be only about 1 Ma.
Pretty gorgeous. I love the high-contrast coloring.
Brian reports that this second image shows:
schist/phyllite taken near the bridge at Tianxiang in Taroko National Park. That same Beyssac study as above found Zircon-He ages of only 0.5 Ma here.
Thanks for sharing, Brian! Happy Friday, all!
8 February 2018
My friend Barbara am Ende posted this image on Facebook the other day, and I instantly swooned over its myriad teeming geoscience lessons. Gaze upon its majesty, ye mortals, and rejoice:
This image shows the Alabama Hills outside of Lone Pine, California, in the Owens Valley, looking west at the eastern slopes of the Sierra Nevada mountain range. What do you see here?
Let’s start with the biggest picture: this photo shows a portion of our planet, Earth. But we are not alone: looking up into the space adjacent to our planet, we can make out a moon. The blue of our atmosphere surrounds that lovely orb, approximately 2/3 lit. We note that the orientation of the shadow of the moon is identical to the shadows we see on the rock outcrops in the foreground. The sun is off to the left, to the south. This is in the northern hemisphere; we’re looking westward. It appears to be late morning or mid-day, on the basis of east-facing slopes being well lit and not in shadow. So I reckon that gibbous moon is waning. Though it’s far, far away, the moon is sufficiently lit that we can distinguish between its older anorthositic highlands and its lower, younger basaltic “maria” (lava flows filling impact craters). We have a view here into another world.
Next up, let’s look at the more Earthy subjects: the mountains and the foreground. The two are separated by the Sierra Nevada Frontal Fault, which is the first of the Basin and Range normal faults headed east from the Pacific Coast, and the dividing line between the Sierra Nevada and the Basin and Range. The many north-south-trending faults of the Basin and Range are due to the singular tectonics of the western United States. For the past 30 million years, the west has been widened, the tectonic stresses imposed by the plate boundary to the west being taken up not only by the San Andreas Fault, but also to a lesser degree (~15%) by deformation a good distance into the continent. This oblique shear (transtension) has caused the rocks between the eastern Sierra and the Wasatch Front to have been stretched most profoundly from east to west. At the surface, this deformation is taken up along normal faults, with the hanging wall dropping down to make Basins, and the footwall left high and dry as a Range. The local example is the Sierra Nevada Frontal Fault, the one we gaze across in this image. The rocks on both sides of the fault are Cretaceous granites -the crystallized results of multiple silica-rich magmatic intrusions into the edge of the North American crust during a protracted period of subduction during the Mesozoic. They are the roots, the plumbing, of a continental volcanic arc akin to that operating in the modern day in the Andes.
But in spite of their common lithologic identity, the granites on either side of the fault look strikingly different. Up high on the Sierra crest, peaks like Mount Whitney (the chunky peak at left, adjacent to the two spiky Keeler Needles) poke up to more than 14,000 feet above sea level. They are subjected to radically different weathering conditions than the Alabama Hills (at only ~5300 feet of elevation). There’s almost 10,000 feet of vertical difference between Mount Whitney’s granite and that of the Alabama Hills.
Up high, it’s cold. The high Sierra has been glaciated, and even retains some permanent icefields and “glaciers” to this day. Some of the valleys draining to the east have a wide, U-shaped profile at their tops, and transition to narrower, V-shaped profiles downslope. During the Pleistocene epoch, the “Ice Age,” the Sierras were swathed in glaciers, with ice flowing downhill under its own weight, plucking and abrading and gouging thereby into the tough rock from which the mountain was made. This glacial erosion hewed the mountain range into a new shape, a sequence of peaks separated by valleys, like the teeth on a saw. The name “Sierra” reflects this – it is Spanish for “saw.” The cornucopia-like shape of the valleys we can see speaks plainly about the changing stability field of ice as elevation decreases. Clambering around in that transition zone, you’d doubtless find faceted erratics and striated bedrock. The fact that the Earth’s climate can shift between warmer and colder states is a fundamental insight of modern climate science. Do you like the temperature outside? “It’s a lovely climate you got here. It’d be a shame if something happened to it…”
Wisps of cloud in the sky remind us of the water cycle that dumped the glacier-forming snow on these mountains during the Pleistocene epoch. There are two tree-lines on the Sierras’ eastern front: an upper one defined by temperature (above which it’s too cold for trees to grow) and a lower one defined by aridity (below which it’s too dry for trees to grow). There’s a 10,000 foot difference between the bottom of the Owens Valley and the crest of the range that stands between it and Pacific moisture. It’s a perfect recipe for a rain shadow.
Down below, it’s warmer, but also in the rain shadow of the wall of mountains to the east. No glaciers at this elevation! Instead, thermal expansion and contraction coupled with exfoliation allows the Alabama Hills’ granite (technically, a biotite monzogranite) to weather into spheroidal forms. There’s a lot of grus about, as feldspars spall off and pile up in gritty piles. This grus is highly porous and permeable, and water tends to sift right through it. Notice how the few plants in this sere terrain either root in the cracks (joints) in the granite, or immediately adjacent to the impermeable outcrops: these are the only sites where water is likely to be retained long enough for a plant to be able to do something with it.
On the shadowed side of the rounded forms you can see a faint orange-colored tinge: probably lichens able to survive on the north side of the boulders, where shadows tend to retain moisture for a little extra while longer. These lichens, a symbiosis between fungus and algae, help aid in breaking down the granite as their hyphae probe microfractures and as they exude acids that enhance the chemical breakdown of the granite’s outer surface. Elsewhere, the Alabama Hills granite have a dark patina — this is desert varnish, an interesting combination of manganese and iron oxides, clays, and biofilm. It makes for good petroglyph opportunities. All told, the rough serrated Sierra in the background, and the worn-down-looking foreground make for good theater: Coupled with the Alabama Hills’ proximity to Hollywood, this place was the filming location for a number of movies, in particular westerns.
Another thing we may notice is that there’s a beautiful aplite dike cutting semi-horizontally through the prominent knoblet of Alabama Hills granite in the right foreground. These fine-grained felsic dikes are common in the plutons of the Sierra Nevada batholith, and thanks to their clear cross-cutting relationship with the host granites, reveal themselves to be younger than the rocks into which they have intruded. It has a closely-spaced set of dike-orthogonal fractures cutting across it, giving it a blocky weathering pattern. These joints formed in the shortest possible direction to cut across the dike from one side to the other, and these fractures of course must post-date the dike. You can’t break something that doesn’t yet exist.
All told, there are many interesting features to be seen in this lovely, well-lit, well-composed image. The great depth of field, where the moon and the aplite dike are both in focus, allows us to explore geological features that extend over numerous scales, near and far.
What did I miss?
7 February 2018
Following yesterday’s discourse on the logistics of virtual samples, I wanted to showcase some new collections of images, focused on giving students practice with relative dating.
Relative dating collection I (36 outcrops and samples)
Relative dating collection II (24 outcrops and samples)
These are super-high-resolution images (GigaPans and GIGAmacros). As with all my GigaPan stuff, you can zoom in to great detail in each of these images. The advantage of having them all gathered on a single web page is that it’s a single URL for instructors to deploy as an access point for their students. In this case, the images are united in a theme of having some sort of relative dating story to be told. Though the details vary by image, the concepts covered include superposition, lateral continuity, original horizontality, inclusions, overprinting (by tectonic fabrics) and cross-cutting relationships. There are igneous intrusions, folded sedimentary rocks, and several kinds of unconformities. The images featured are mostly mine, but also include a substantial contribution from my colleague (and former student) Robin Rohrback, and a handful from other student researchers and 3 more from my colleague Ron Schott.
I used five of the images on the first page in Historical Geology class the other day, one at a time (I told students to bring their computer or smartphone or tablet in advance). After they worked on exploring and thinking about an image individually for a few minutes, I then reviewed it as a class discussion. Then I assigned another: “Try number 4 next!” and so on. In the discussion portion of the lesson, I was able to offer prompts, such as “if this sill is isotopically dated as being 300 million years old, then how old are the sedimentary layers it intrudes?” Then I gave them another set of images to do for homework.
It’s a nice switch-up for applying the principles of relative dating to real-world rocks. I also think it’s valuable because it weaves in rock identification skills with the relative dating concepts. I share this compilation with you teachers in the hopes that it may be useful as the basis of an in-class exercise or a homework assignment.
If you want more detail on the sequence of events/rocks in any of these images, I’d be happy to share their story – but you can doubtless work out the key things in each one on your own. Some are more straightforward than others.
It strikes me that people might feel overwhelmed by the numbers of images per page, and there’s an argument to be made for smaller groups of samples. So here are the same images, but now organized into 5 smaller pages of a dozen images apiece:
Relative dating sub-collection A (12 outcrops and samples)
Relative dating sub-collection B (12 outcrops and samples)
Relative dating sub-collection C (12 outcrops and samples)
Relative dating sub-collection D (12 outcrops and samples)
Relative dating sub-collection E (12 outcrops and samples)
Here’s how I envision you using these. Deploy one set for a pre-lesson homework assignment to warm your students up, then another set/page for an in-class exercise, then a third for a post-lesson homework assignment, all offering opportunities for the students to get feedback from their instructor, both affirmational and corrective. Then there’s a couple sets left in reserve: one for extra practice for students who need it / want it, and another for a final summative assessment.
I welcome your feedback and thoughts.
6 February 2018
I love the idea of high-resolution imagery that users can explore for geological meaning from the comfort of their computer screens, tablets, or phones. I think that 3D models and gigapixel-resolution panoramas (GigaPans) are powerful media for connecting people with the Earth. They allow improved access for many populations. Long-time readers will report that I regularly used to embed GigaPans in this blog as part of the stories I tried to tell.
But it’s been a rough few years for the technology of GigaPan. Shortly after I was seduced by the medium, the GigaPan company went belly-up, and the parts of the company (the software part, the hardware part, and the image-hosting website part) went their separate ways. Though it’s still possible to make GigaPans and upload them to GigaPan.com, the website is a ship without a crew. One consequence of this is that no one’s updating its code to match the march of time, the progress of technology. Because the website doesn’t support https (as opposed to old fashioned http) URLs, it’s no longer considered secure to embed their images in blog posts here on Mountain Beltway. This is a shame because it renders dysfunctional all those virtual field experiences (VFEs) that I’ve built up here over the years. I made them to be awesome, but now they are broken.
I also built up a huge repository of exercises and collections on my NOVA faculty website, some of which mirrored content originally posted here on the blog. (I’d link to it here, but that link would be worthless, as you’ll see below…)
The earliest version of the embedding code (to stick GigaPans as live, dynamic images within some other webpage, like a blog post) was based on Flash. The Flash-based embed code was functional on several fronts: it allowed the person doing the embedding to select certain snapshots (little highlighted areas) to include while excluding others that were tangential to their purpose. It didn’t have a title, which was good if you use the imagery the way I do: by having students figure out what’s going on in these images. Along similar lines, it didn’t have a direct link back to the source image page. (Some tech-savvy students figured out how to get back to the source page by reading the HTML that coded for the embed, but most didn’t – and took the exercise at face value.)
That said, it was Flash — and you know how people are about Flash. The medium, so vital and promising when first released, has been in the process of being “deprecated” (made to go away) for years now. But it persists nonetheless. Many browsers and devices don’t support Flash, and it created technical problems for my students — problems that got in the way of learning. I spent a decent amount of time each semester coaching students down the one or two paths that would lead to successfully accessing the material.
Fortunately, one of the last major acts of the GigaPan company prior to folding was to install an HTML5-based embedding code on their website, assuming that users (i.e., those who posted the images) clicked the “it’s okay for other people to embed my images” button. This allowed a non-Flash embed, but while it’s MUCH more widely accessible, it doesn’t allow snapshots and it does automatically link back to the source image, which is a bummer for those seeking to drive students to make their own observations and conclusions. It’s also not intuitive, but a unique identifier of garbled letters and numbers for each image. (This makes it harder to systematically program; each identifier has to be retrieved individually. It would however also negate the efforts of the tech-savvy students to reach back and find where the imagery was coming from vita the HTML – but of course they don’t have to, since the link is right there on the image!)
I was in the process of slowly updating my curriculum by reprogramming the collections and VFEs to the new HTML5 version, when last fall my college made the sudden decision to put all faculty webpages behind a password-protected access wall. This was motivated by a desire to be in compliance with ADA accessibility requirements for their public-facing content. We were given a couple of weeks of notice; all public-facing content created by faculty disappeared at that point. Though students could still log in and access the web pages I had created, the embedding integral to the web pages was now broken by the new ‘password wall.’
So my hand was forced, and I began migrating material over the the GEODE website, the site established to showcase the digital materials that my colleagues and I produced through the Google Earth for On-site and Distance Education project over the past five years. This site too isn’t a perfect venue, as all its pages bear the same (link-filled) banner (I’d prefer a blank slate), but at least it’s stable, and it’s HTML5-capable (though Flash works there too). Here, for instance, are a few of the pages I’ve built there over the past few months:
Wind River Canyon, Wyoming (Flash-based)
Wind River Canyon, Wyoming (HTML5-based)
Massanutten Synclinorium, Virginia (Flash-based)
Massanutten Synclinorium, Virginia (HTML5-based)
Rathlin Island: kilometer to micron (Flash-based)
Rathlin Island: kilometer to micron (HTML5-based)
Sedimentary deposits in the Canadian Rockies (Flash-based)
Sedimentary deposits in the Canadian Rockies (HTML5-based)
Siccar Point, Scotland (HTML5-based, including 360° spherical photos and 3D models)
Metamorphic rocks virtual collection (Flash-based)
Metamorphic rocks virtual collection (HTML5-based)
I’ll share another set tomorrow. These aren’t perfect, but I think they’re almost as good as they can be at this point, given the suite of options available. Please explore & get back to me with your feedback.
Meanwhile, the GIGAmacro company, whom I’ve been thrilled to collaborate with these past 6 or 7 years, has launched an imagery server of their own. Here’s an example of a gallery of geological images hosted there. This has a much higher degree of functionality than even the best that GigaPan.com ever managed. It has a dynamic scale bar, point, line, and polygonal annotations. The images can be rotated, inverted, layered, compared. It’s the bee’s knees. Here’s a gallery I put together for the last GSA annual meeting, of images we’ve made relative to the latest-Devonian Spechty Kopf Diamictite in the Appalachian Valley & Ridge province. (I previewed some of the features of the GIGAmacro viewer in this video before GSA.) I think their platform is the future for this medium, with a much wider range of tools and a commitment to quality assurance that can no longer be expected at the GigaPan site. The problem there is that I’d have to port all of my imagery over to GIGAmacro from the GigaPan site, and again, that has to be done one at a time. It’s quite time-consuming, all of this, and is a reason why my productivity here on the blog has suffered in the past half a year. Not to mention, my amount of available material has been severely throttled too.
I figured I should spell all this out, since long-time readers will doubtless be wondering what happened to that initiative.