This Friday, let’s return to Glacier National Park. Here are some folds in Helena Formation limestone: Can’t see them? Fair enough – the point of maximum inflection appears to be hidden behind a snow-filled gully: But in addition to that big fold, there are several kink bands in there, too. Let’s zoom in: Here they … Read more
This morning on Twitter I was reminded of komatiites, those “extinct” ultramafic lavas that were relatively common eruptions during the Archean. I’ve actually got a good number of komatiite photos to share from my time last year in South Africa’s Barberton Greenstone Belt. But since time is short this morning, I’ll start with a short … Read more
What does it mean for a vein to be “quantankerous?” Well, to start with, it’s quartz. Second, it has to be disagreeable or cantankerous. This vein, seen in meta-arkose of the Catoctin Formation near the summit of the Blue Ridge at Rockfish Gap (not Afton Mountain), is such a quantankerous individual: You’ll notice its “S” … Read more
I’ve been reading a fair bit of Neil Gaiman over the past year or so: American Gods, Good Omens (with Terry Pratchett), and The Ocean at the End of the Lane. Each of those books is good in its own way, and each is fiction. I just finished a compilation of Gaiman’s nonfiction, and there … Read more
Over the summer, I treated you to a great big kink fold in the sedimentary rocks of Glacier National Park. Here’s another set: Did you see both of them in that first picture? – one bigger down below, one smaller up above. Both kink bands dip to the left. Let’s zoom in on the upper … Read more
The 2017 Virginia Geological Field Conference had a heavy arkose infusion. Meet some of these feldspar-rich Neoproterozoic sediments of the Lynchburg Group.
It turns out that Rob Reid can write. This “novel of Silicon Valley” is a tour de force of writing. Reid shows off his chops at writing potboiler adventure stories, ironic Amazon reviews, and sparkling dialogue. It’s a story of Silicon Valley culture, of start-ups and venture capital and social navigation in the Bay Area, … Read more
Happy Friday! Here’s a sample from the Smithsonian Institution’s National Museum of Natural History in DC: As the label says, we have a nice example of ptygmatic (“intestine like”) buckle folding here. It comes from Finland. The coarse equigranular crystals in the vein appear to be mainly potassium feldspar and quartz. The surrounding matrix has … Read more
Italy’s celebrated archaeological site of Pompeii is compared and contrasted with nearby Herculaneum in terms of art, architecture, visitor experience, and (of course) geology.
Braiding Sweetgrass is a collection of thematically-linked essays by Robin Wall Kimmerer, an environmentalist, academic, and Native American. The themes that unite them are plants, the human relationship to the natural world, and love. I’ve read Kimmerer’s essays in Orion before, but there’s a sort of literary force multiplier when you get a whole book … Read more