29 July 2015
My friend Barbara am Ende sent along this lovely image of a dike in Colorado:
Here’s the site. You can see the dike in Google Earth.
Dikes are fractures, filled with molten rock, which then cools and solidifies, sealing the crack shut. In this case, once it got uplifted to Earth’s surface and exposed, the dike rock is tougher (more resistant to weathering) that the older rock it cut across. As a result is weathers “proud” of the landscape. It is being eroded at a rate slower than the rock on either side of it. This isn’t necessarily the case – not all dikes weather out like the Great Wall of China. Along Mather Gorge (Potomac River, downstream of Great Falls), a quartet of lamprophyre dikes weather away negatively, resulting in tabular recessed features on the landscape, which is otherwise dominated by metagraywacke:
And here’s another negatively-weathering example: basalt (later metamorphosed to lower greenschist facies) intruding granite on Old Rag Mountain, Shenandoah National Park, Virginia:
Thanks for sharing, Barbara!
28 July 2015
Another site from the GMU sedimentology field trip in April: An outcrop on Route 33 in Brandywine, West Virginia, showing the Millboro Formation. It’s mostly shale, with some intriguing sandstones, too. There are fossils and diagenetic carbonate nodules (concretions).
Here’s the outcrop, the largest GigaPan I’ve taken so far (7.9 billion pixels):
The shale itself looks… like shale. It’s fine-grained, and dark (high carbon content, suggesting low oxygen levels when deposited). It contains articulate brachiopods that are also suggestive of less-than-ideal-conditions-for-animals conditions. Here’s a look down on a bedding plane, for instance:
The little bumps are brachiopods. The trained eye will also pick out some subvertical crenulation cleavage ‘wrapping’ around these little guys:
This next slab has the brachiopods, too but also seems to contain a few snails (spiral shapes):
Another fossil is a long, spear-point-shaped thing. Does anyone have any idea what it is?
Maybe acanthodian spines? (early sharks)
The shale breaks apart with a characteristic pattern called “pencil cleavage”:
Some close ups of the sandstone layers, which show cross-bedding, climbing ripples and convoluted bedding, suggesting rapid deposition:
This one is a boffo example of convoluted bedding:
Annotated, with laminations internal to the sandstone bed traced out in blue:
Note that the shale above and below is NOT deformed – this is soft sediment deformation rather than tectonic deformation of rock. Look closer:
Here is a sample that had weathered out of the outcrop. I took it, of course.
Another sandstone package, lower in the outcrop (older):
This next shot is a close-up of the upper left corner of the previous image:
Further along strike, apparent climbing ripples could be seen:
Here’s a loose climbing ripple sample, with out-of-focus West Virginia scenery in the background:
Close-up showing the changing in angle of the bedding in this same sample:
Sandstone chunk showing cross-bedding and plane laminations:
Carbonate nodules appear as positively-weathering features in certain horizons:
Here is a little tiny one:
What fun! There’s a lot to see at this site.
27 July 2015
There’s something about conglomerates that just draws me in. Here’s a lovely example — you might even say it’s an exemplar — from Sandy Hollow in Montana:
That’s the basal conglomerate of the Cretaceous Kootenai Formation, one of the mappable units in this mappable region.
Feast your eyes on those well-rounded pebbles!
25 July 2015
I am way, way, way behind in reporting on the books I’ve read. As time goes by, the list gets longer, and the “book report” more daunting… So I’m going to do a brief book report in hopes of clearing out the backlog:
What if? by Randall Munroe
Really entertaining scientific answers to ridiculous questions, by the cartoonist author of XKCD. Highly recommended. Unique.
The Owl Who Liked Sitting on Caeser, by Martin Windrow
A memoir of a man with a pet owl, first in London, then in the countryside. The owl does funny things; the man writes about them pretty well. About what you’d expect, really.
The Human Age, by Diane Ackerman
An exploration of the Anthropocene. Ackerman’s earlier books are quite good (The Moon by Whale Light, A Natural History of the Senses), so I had high hopes for this one, but it’s not as good as Elizabeth Kolbert’s The Sixth Extinction, though it covers much of the same ground in more flowery, less informative prose.
Spillover, by David Quammen
A chilling examination of zoonoses, those diseases that can jump from animal reservoirs into humans. Essential reading in the age of Ebola. This was on my mind yesterday as I attempted to evict some bats from roosting in my roof.
Rust, by Jonathan Waldman
An exposition on the subject of corrosion; a series of essays dealing with different aspects of the general subject of the chemical breakdown of stuff we depend on. Some are quite elegant and reminded me of John McPhee’s work (the Statue of Liberty one that opens the book, as well as the one on “Can School”). Others seemed protracted and dull (the one about the guy at the Pentagon who is making videos about rust). A mixed bag.
No Logo, by Naomi Klein
A classic of anti-consumerist sentiment. Feels a bit dated to read it now, twenty some years after it was first released, but it includes some chilly reminders of how deeply and intentionally corporate branding has woven itself into the fabric of our modern society. It looks closely and critically at advertising strategies that you don’t even notice any more, they’re so much a part of your life.
The Sense of Style, by Steven Pinker
This is a book about writing, by ‘public intellectual’ Steven Pinker, author of numerous accessible, insightful books. He has the authority to discuss what makes good writing good, and how to avoid traps that lead to turgid prose. I first heard of it on the excellent podcast Point of Inquiry, hosted by Lindsay Beyerstein.
How the Mind Works, by Steven Pinker
Awesome. An examination of how the brain produces the mind, and its many manifestations. It’s masterful science writing, clear and creative and insightful. Top notch.
Reason in a Dark Time, by Dale Jamieson
A review of the history, ethics, economics, and philosophy of climate change science, climate change denial, and climate change politics. The book’s premise is that the efforts of climate scientists and environmental activists to prevent climate change have failed, and failed for identifiable reasons. Jamieson enumerates the relevant factors and explores the consequences. It’s a sober and grounded analysis, though I didn’t find it as perspective-altering as Jonathan Franzen did in the New Yorker essay that initially alerted me to Jamieson’s book.
Why Are You Atheists So Angry? by Greta Cristina
An angry answer to the title question. Thought-provoking and righteous: a methodical examination of 99 really good reasons to be angered by religion’s influence on culture and by the way religionists can treat those who don’t believe in any gods.
Galileo’s Middle Finger, by Alice Dreger
A fascinating book about activism and justice within the realm of science. The author is a long-term activist on behalf of the rights of intersex people, and this background is relevant to the several controversies she explores in the book, and so she devotes a lot of time to her backstory in the early portion of the book. In pushing for those born intersex to make their own decisions about whether to engage in surgery, or which gender to assume (or not to assume), Dreger was forced to become literate in the science of gender and sex, and encountered significant societal resistance in the form of doctors who were practicing what they had been taught. She relentlessly worked to teach the experts using information, and helped to effect a widespread change in the procedures for nurturing intersex children. Coming out of this constant struggle of facts and ethics vs. cultural inertia, arguments and conflict were part of her daily life. When she heard of notorious allegations against a colleague studying transgender issues, she inferred that “where there’s smoke, there must be fire.” A group of transgender activists were vilifying this particular academic for the conclusions he presented in a book, and were rallying the forces of activism (some of which Dreger helped build) to demolish his reputation. When Dreger looked into it, though, every allegation turned out to be baseless, and while she acknowledges a bit of a tin ear in the accused researcher, she presents a compelling case of the injustice he was subjected to at the hands of those who didn’t like his data-driven conclusions. This sounds very familiar to anyone who maintains an interest in the cultural clash between scientific conclusions and the religious or political myths they deflate (evolution, climate change), but it is a compelling example of the same sort of dynamic playing out in a subject area that is completely independent (territory previously unknown to me). Several other cases are presented of similar phenomena, but the bulk of the book is devoted to the situation described above. The title of the book comes from Dreger’s discovery that when Galileo Galilei died, parts of his body were removed as relics, in the same sense that religious people removed bones from saints as holy relics. One, on display in Paris, is Galileo’s middle finger. (Galileo is of course famous for following his astronomical observations to their logical conclusions, even though these deductions violated the Catholic religious dogma of his day.) In this symbol, Dreger sees a message for all controversies in science: follow the data and reason, and flip the middle finger to dogma and ideology.
Descartes’ Bones, by Russell Shorto
An entertaining look at the history of Rene Descartes, his contributions to intellectual discourse (he invented science, essentially, with his Discourse on the Method, which included that line often translated as “I think, therefore I am” — a grounding of knowledge in essential foundational observations) and also invented dualism (the idea that people have an immaterial soul separate from their physical body). When Descartes died, his physical remains took a fascinating journey, becoming disassociated and revered as relics along the way (kind of like Galileo’s middle finger, as noted above). The bones became fodder for many of the most seminal philosophical and scientific questions of the day. His skull was used to refute phrenology, for instance.
The Soul Fallacy, by Julien Musolino
I was alerted to this one by the same excellent podcast Point of Inquiry, that first led me to Steven Pinker’s work. Musolino appeared there, with host Josh Zepps, to promote the book. Ever since Descartes (see above review), most people have embraced the idea of an immaterial soul that is somehow imbued into our bodies, and persists after our corporeal death. But science suggests otherwise, and Musolino reviews the relevant literature that has led to the scientific rejection of the soul hypothesis. A useful little compendium.
Faith versus Fact, by Jerry Coyne
Apeaking of which… the title says it all. Coyne doesn’t see faith as compatible with fact. Writ larger: science and religion are irreconcilable. He explores why. It’s not nearly as compelling a book as his excellent volume Why Evolution Is True, but it is comprehensive, and to my reading, exhaustive. One starts with the conclusion and sticks with it in the face of evidence to the contrary. The conclusion is permanent, immune to falsification. The other starts with evidence, and uses it to reach tentative, falsifiable conclusions. How could they be compatible? Clearly they are diametrically opposed. Why would someone of Coyne’s talent waste time writing a book about such a thing? In short: because many people pretend that science and religion can get along, an attitude endorsed by many people and organizations, including The National Center for Science Education and the AAAS’s Dialogue on Science, Ethics, and Religion. It’s a bit of an “elephant in the room” issue, and I applaud Coyne for taking the time to show why such accommodationism is logically incoherent, tough as that may make things for those of us who promote science in the hyper-religious United States of America.
Final note: 4 of the 13 authors listed here are women – so I’m doing better at diversifying my reading list than I had been doing earlier this year (as noted at the end of this post), but I’m not even to parity yet. And every single one of these people is white, so the racial diversity of my reading list is abysmal. Sheesh.
Help me out, readers: Any recommendations for new books to read?
24 July 2015
A final Friday fold (for now) from Howard Allen:
This is :
A view south across Kananaskis Lakes, Peter Lougheed Provincial Park, Alberta, through mist/low-hanging clouds. Snow highlights the Sarrail Creek Syncline and Warspite Anticline on the north faces of mounts Fox (left/east) and Foch (right/west). Rocks are Lower Carboniferous carbonates of the Banff, Livingstone and Mount Head formations.
Happy Friday all – and thanks for sharing all these great folds, Howard!
23 July 2015
After reading the post last weekend about the discordant offshoot of the Purcell Sill, Rich Gashnig (post-doc at Georgia Tech) sent me a few photos he shot at Piegan Pass (at the head of a side-canyon adjacent to the one containing Grinnell Glacier). They show the Purcell Sill leaving one stratigraphic horizon and jumping to another, with the intermediate zone of Helena Formation limestone bending to accommodate the different positions:
In addition to the main, obvious jump at left-center, there are two other offsets (one,perhaps, apparent offset) further to the right:
Thanks for sharing, Rich!
22 July 2015
Another gem from the Grinnell Glacier cirque:
Zooming in on the contact, showing the concentrically-zoned ooids:
Near the tip of the flame structure (?), I noted alignment of longer platy / flaky components within the oolitic layer:
This looks like a loading structure – soft sediment deformation due to a density inversion – perhaps when some high-energy event (a storm?) dumped a bunch of relatively coarse ooids atop some squishy micrite mud. The upper oolitic layer glooped down into the micritic lower layer, creating this convoluted contact.
18 July 2015
The Neoproterozoic Purcell Sill is a stark, obvious black stripe in the strata of Glacier National Park. Here it is emerging from behind “The Salamander” glacier, above Grinnell Glacier Cirque:
Zooming in, you can see the “baked” (bleached) zones above and below this concordant intrusion.
But this time, during my visit to this special place, I noticed a discordant offshoot from the main sill:
See it? Up there at the head of that valley:
Zooming in further, you can see four people standing on the contact metamorphosed zone on the left side of this dike:
I went and searched for it in Google Maps, and found it quite easily emerging from that icy valley;
How this escaped my notice during my previous trips to this site, I’ll never know. I was glad to find something new there, though.
16 July 2015
Here’s a really cool hand sample my student Xiuming found when were were exploring the waste rock piles at the Golden Sunlight Mine near Whitehall, Montana, the week before last:
That’s a vein of pyrite and chalcopyrite, offset along a series of three small fault zones:
Pocket faults! Three for the price of one.
10 July 2015
View of Lawson Syncline looking obliquely along strike (SSE) from an unnamed peak SW of Mount Inflexible, Kananaskis Range, Alberta. The axis of the syncline forms the bottom of the valley and plunges slightly toward the south. The syncline is in the hanging wall of the Sulphur Mountain Thrust sheet. On the right side of the photo, beds can be seen dipping to the right (west) in the ridge the photographer is standing on, evidence of the adjacent Kent Anticline, whose axis is eroded but would be above the right side of the valley. Rocks are Carboniferous to Permian Etherington Formation to Rocky Mountain Group carbonates and clastics on the flanks of the folds and recessive Triassic clastics of the Sulphur Mountain Formation forming the core of the syncline (now mostly eroded; remaining beds are most vegetated, down-valley).
Of course, that’s another gem from longtime reader and contributor Howard Allen. Thanks, Howard!