15 June 2018
My friend Karen Aucker from NAGT’s Eastern Section shared these images (and a video!) of the folds she glimpsed from the cable-car on her way up the Schilthorn in Switzerland. I reckon they will do for our Friday fold:
Thanks for sharing, Karen! These are great.
Happy Friday, all!
9 June 2018
Today, in Millersville, Pennsylvania, on the campus on Millersville University, I saw these contorted carbonates. They are of the Cambrian Conestoga Formation, and I saw them on a NAGT Eastern Section field trip led by Lynn Marquez of Millersville University.
This deformation is purported to be Taconian, but it looks very much like Alleghanian deformation in similar aged and composition rocks in Virginia. Interesting!
5 June 2018
When I was learning about the Archean from the perspective of Barberton Mountain Land in South Africa, I was expecting to see komatiite lava flows. Early on in Earth history, the planet was hotter: (1) it was closer to the many thermokinetic impacts that built the planet from stone-cold meteorites, and (2) there were many more unstable radionuclides around, decaying and releasing their energy into the young planet. As a result, some minerals that don’t melt readily at modern volcanoes were able then to turn to liquid and ooze out of volcanoes at temperatures much higher than modern eruptions. As they crystallized, these lava flows grew “chandeliers” of spinifex textured olivine and pyroxene crystals.
However, I was not expecting to see primary sedimentary structures in these ash deposits. Some of the ultramafic volcanoes blew up, sending ash into the Archean atmosphere, from where it rained down as itty-bitty particles. In addition to accretionary lapilli and tsunamites (with accretionary lapilli!), the komatiite ash deposits show current flow indicators such as cross-beds, indicating they were moved around by currents of either air or water prior to final deposition:
These cross-beds are concave-up (like smiley faces), and if you’re astute, you’ll be able to find a few instances here where the top of the cross-beds are truncated by an overlying bed. Here’s a GIGAmacro example of that, with cross-bedding annotated in blue, and the bottom of the overlying bed in gray:
Note also the rusty patina of these ultramafic volcanic/sedimentary rocks – the olivine therein is ready to rust, even in the arid climate of South Africa.
4 June 2018
Last week, I lost two of my colleagues, Declan De Paor and Ron Schott. Both were involved in Google Earth for On-site & Distance Education (GEODE), the 5-year project I serve as PI on. Declan had battled various forms of cancer for many years, and most recently had developed several brain tumors. His passing was preceded by knowledge of his condition, while Ron’s death was unexpected and therefore shocking. Both geologists were important to me personally, and I wanted to commemorate them here, outlining both their roles in larger geo-society, but also what their influence meant to me.
Declan taught at Old Dominion University, where he directed the planetarium and had an appointment in the department of geophysics. He was a structural geologist (as is his wife, Carol Simpson, who served as provost at ODU for many years), but he was more known in recent years for his innovation and promotion of digital geology teaching tools. Many of his collaborations through the years were with Steve Whitmeyer of James Madison University, and it was the two of them who contacted me about six years ago to start developing a proposal that became GEODE. Declan was exceptionally clear-headed and proactive as a thinker. I remember first meeting him at a GSA meeting in Pittsburgh, as he mediated (with a martini) about a way to solve a technical issue with his planetarium, and delightedly coming to a solution right before shaking my hand. He was gleeful in that moment, and keen on sharing his insight with me, and it was emblematic of his positive attitude about all things, including problems. He smiled very easily and exuded charm and sincerity. His Irish accent added to this effect. I’m grateful to Declan and Steve for bringing me into the fold of Principal Investigators, giving me an opportunity to learn project leadership. Declan also initiated the nomination process that led to my GSA fellowship last year, an honor I’m quite grateful for. Declan retired recently and moved to the island of Mallorca in the Spanish Mediterranean, and I’m glad he got to enjoy living there for some time before his passing away. My condolences to Carol and his surviving family.
Ron Schott was a giant in geoscience outreach on the internet. He was an early adopter of just about every technology you can think of: Google Earth, GigaPan, Twitter, Google+, geological apps for augmented reality. He was always pushing to innovate for the public good with these technologies, making publically-accessible “Geology Office Hours” on Google hangouts and inventing new geo-ed hashtags like #weatheringWednesday and #btgt (“Been there; GigaPanned that”). He was the king of “Where on Google Earth?” so much so that the players of that game invented “the Schott Rule” in his honor. He was kind and inclusive, encouraging and thoughtful. His omnipresence on geology Twitter was pretty much unmatched. When I announced his death there last week, the outpouring of grief was unprecedented. Ron was unlucky in work: he didn’t get tenure at Fort Hays State University in Kansas, nor at Bakersfield College, but he was absolutely dedicated to public outreach via the web and he stayed in Bakersfield anyhow. The online world was his domain, and he excelled at that work. Nobody did more to push GigaPans on the geology world. Ron had almost 1500 to his name. Though I ended up in the PI position on GEODE, Ron was the pioneer, and in many ways I was following in his footsteps. When I was a GigaPan tenderfoot, Ron connected me at a conference with Gene Cooper of Four Chambers Studio (later to branch out and become GIGAmacro), who also became a GEODE collaborator. Without that connection, I’m not sure what my digital legacy would look like: our team’s GIGAmacro images of geological subjects are one of our major contributions to digital geology. Without Ron, I wonder if it would have happened. Prior to that, I had launched a geology blog aimed at my students, but it was Ron who encouraged me to open up the comments so other people could interact with it. That was huge – if he hadn’t nudged me to have the blog be a conduit for a two-way conversation, I wonder if it ever would have developed into what it became, and I wonder how much of my personal success would never have manifested. It’s an interesting question – how much of a catalyst can one person be for another’s life path? The commemorations I’ve seen play out on Twitter the past few days have shown me that I am not alone in having been seriously and positively influenced by Ron. He has manifested hundreds of other instances of proactive awesomeness, helpfulness and growth among my peers and his followers online. My condolences to Ron’s sisters and surviving family.
Both of these geologists were great people. Both of them will be sorely missed. We are lessened by no longer basking in their glow.
Rest in peace, gentlemen.
1 June 2018
Marli Miller is a senior instructor at the University of Oregon. She is the author of Roadside Geology of Oregon and (with Darrel Cowan) Roadside Geology of Washington. She’s also a very talented geological photographer. She launched a website recently to showcase her work and make it available for instructors: Geology Pics. After chatting with Marli a bit in Flagstaff at the Rocky Mountain / Cordilleran section meetings of GSA a few weeks ago, I got her permission to share a small sample of her lovely fold photos with you here.
Similar folds (passive folding) in marble and quartzite. Rock is of the Plattenkalk Series, Crete, Greece:
Axial planar cleavage and folds in quartzite:
>Proterozoic Banded Iron Formation, folded into asymmetric anticline:
Soft-sediment deformation expressed as folded Pliocene lakebeds of the Coso Formation, SE California:
There are many more awesome fold photos to be seen at Marli’s Geology Pics website, as well as geology themed images on many other subjects. Go check it out and explore!
Thanks for sharing, Marli.
25 May 2018
This is a block of rock I found in the rock garden at Northern Arizona University a few weeks ago:
It’s intensely folded. Not sure what kind of rock it is, but it was quite dense.
18 May 2018
My friend Ryan Thigpen is phoning in his contribution to the Friday fold from Corsica. He says:
found you a couple of Friday folds in blueschist facies serpentinite on the east coast of Corsica….including one of the best quartz sheath folds I have ever seen…
13 May 2018
As mentioned the week before last, Walter Alvarez has a new book out. I’ve read it. It’s good. It’s Alvarez’s take on what he calls “Big History” – the story that spans the cosmos, the Earth, life, and humanity. It’s pretty great for the reasons that Alvarez’s other books are excellent – his voice is calm, appreciative, and patient. His language is accessible and appropriate (though I will grouse that the audiobook version mispronounced some words and names, like “Tethys”). Alvarez’s narration of Big History comes across as vital, essential, and hidden in plain sight. His own research in Italy, and in unveiling the case for an extraterrestrial impact trigger for the end-Mesozoic extinction, features as part of this narrative, but it’s in no way the focus. He delights in all parts of the story, though his perspective and authority are principally in the Earth sciences, so most of the book is focused there. It’s a well-written account of what we know about what happened when and why. I found it very enjoyable, and occasionally enlightening. Recommended.
10 May 2018
A reader of this blog recently recommended Michael Punke’s Last Stand. I thoroughly enjoyed his novel The Revenant, and so last week I started the audiobook version of the nonfictional Last Stand (2007). Last Stand is subtitled “George Bird Grinnell, the Battle to Save the Buffalo, and the Birth of the New West.” Prior to reading it, I knew little of Grinnell, save that he was a conservationist, and that he was the namesake of the Grinnell Formation and Grinnell Glacier in Glacier National Park, Montana (one of my favorite places on this planet). The book is simultaneously a biography of Grinnell but also an exploration of the national saga that brought U.S. bison (“buffalo”) numbers down to ~230 at one point, before being restored. This single species’ near-extirpation was a significant catalyst for the conservation movement as a whole, helping nucleate a conservation lobby in Washington that helped counter rapacious policies advanced by the railroad industry. It also took some serious convincing to get Senators and Congressional representatives to value the lives of bison sufficiently that they punished those who poached them from the newly-created Yellowstone National Park. Punke lays out the case fairly compellingly: if not for Grinnell’s passion and grit, there would be no U.S. bison today. Not only that, but “America’s best idea” (the preservation of park land) might have been stillborn if not for Grinnell’s advocacy on behalf of law enforcement in the park. Regulations needed to carry weight, and park authorities had to be able to arrest people and send them to jail for their wanton slaughter of the park’s wildlife.
Grinnell was tied to many notable individuals from history. He was taught as a boy by Lucy Audubon, the widow of renowned ornithologist and painter John James Audubon. At Yale, he was mentored by Othniel C. Marsh and first went west on an expedition in search of dinosaur remains with Marsh (Punke never mentions the “Bone Wars,” by the way), and returned the following year to participate in the last great hunt of the “buffalo” with the Pawnee tribe. He returned on another expedition to the west under the command of the egomaniacal George Custer, but declined a follow-up trip that ended up leading Custer to his death at Little Big Horn. Grinnell was the geologist who accompanied the Ludlow expedition in 1875 to survey the newly-established Yellowstone National Park, where he viewed firsthand the extraordinary anthropogenic pressure on the dwindling reserves of bison there. Upon earning his PhD, Grinnell assumed the editorship of Forest and Stream magazine, which he used as his platform to promote conservation measures and policy and a new environmental ethos. It was his work on the magazine that brought him into contact with young Theodore Roosevelt, and together the two would found the Boone and Crockett Club, which was another instrument that exerted pressure on Congress to enact conservation measures. Late in life, he discovered “the St. Mary region” and advocated for it too to be set aside. He won that battle too, and today we can all go to Glacier National Park and be thankful for his success.
Punke writes with authority and economy. This is an excellent summary of an important individual and an important story in the history of the American continent. Recommended.
7 May 2018
Yesterday I finished a new GIGAmacro image, a view of a chunk of Tonoloway Formation showing what I thought were exquisite graded beds in these Silurian shallow-water carbonates. Closer examination revealed several other primary sedimentary structures with geopetal value: desiccation cracks (“mud cracks”) in cross-section, with their V’s opening upward, and a small instance of scouring and filling, where the pre-existing mud deposit was eroded by energetic sand transport, and sand filled the resulting hollow. Three for the price of one, in terms of determining younging direction. There were also some ambiguous mud cracks, and at least one example where the V pointed the wrong way. But the preponderance of the evidence was pretty clear to me, and I thought it was a good teaching example. I deliberately imaged it with bedding “vertical” in the frame of the image. Here it is:
I posted a link to the GIGAmacro on Twitter and asked:
Students: Which way is stratigraphic “up?” There are three primary sedimentary structures here to clue you in to younging direction: https://t.co/iyVo31fHB6
— Callan Bentley (@callanbentley) May 6, 2018
As you can see, about a third of respondents chose “left” and two thirds picked “right.” In this case, right is correct. (“It’s right!”) But since 1 out of every 3 respondents picked incorrectly, it appears there is a lesson to be taught here. To make the case for why stratigraphic “up” is to the right, consider this annotated copy of the image:
Click on the different annotations and see if you agree. I’ve marked the “right is up” ones with yellow circles, the ambiguous ones in pink, and the “right is wrong” one in gray.
Thanks for playing! More of this sort of thing in the future, utilizing the capabilities of the powerful GIGAmacro imagery viewing platform.