Climate change books: fact & fiction
Callan reviews two books about climate change: the nonfiction account by Michael Mann, and a fictional thriller set in the warmed Arctic of the future.
Callan Bentley
Blue Ridge Thrust Fault field trip
One of Callan’s former students leads a field trip to examine the western edge of the Blue Ridge geologic province, attempting to answer the question of whether the Blue Ridge / Valley & Ridge contact is indeed the trace of a thrust fault. Breccias and S-C fabrics tell part of the story…
Macro GigaPans of Florissant insect fossils
Today, for your viewing pleasure, please check out five macro GigaPans of insect fossils from the Florissant fossil beds in Colorado (34.07 +/-0.10Ma). These amazing specimens were collected by Joe Cancellare, a student working on research supervised by Josh Villalobos of El Paso Community College in El Paso, Texas. Our M.A.G.I.C. project is helping Joe … Read more
Pliegue de Viernes? No, pero es una roca ígnea de México
I got an email a few weeks back from Moritz K., a PhD student at the Universidad Nacional Autónoma de México (UNAM) in Querétaro. He wanted to offer up a potential Friday fold. Here’s what he had to say: I wanted to send you a couple of pictures of folds I took in my PhD … Read more
Friday fold: Japanese garden
Richard Littauer, a MSc student in Computational Linguistics at the University of Saarland (on Twitter at @richlitt) sent me today’s Friday fold. It comes from a garden at Nijo Castle in Kyoto, Japan. Definitely some wavy layers there. It’s a lovely specimen that would add gravitas to anyone’s garden. Not sure what it is – … Read more
Red Bluff Granite, and what it intruded into
Returning to his February field trip in west Texas, Callan examines the contact zone where the Red Bluff Granite intruded into a group of surficial rocks, including columnar-jointed basalt.
Slip-shine
When are sedimentary layers also faults? …When the slab-like layers slip over and under one another during the act of folding. Structures traditionally confined to faults show up on the bedding plane in these circumstances. Callan shares a shiny example from West Virginia in the form of an animated GIF.
Kink fold in Castner Marble
One more structure from the Castner Marble. This one is clearly tectonically-induced: Top to the left! (East over west)
Castner Marble
The Castner Marble is an extraordinary Mesoproterozoic limestone (later re-crystallized and metamorphosed) that exhibits some primary structures (both explicit and ambiguous) and some secondary (tectonic) overprints. It’s exposed in the Franklin Mountains of west Texas.
Slick!
Slickenlines (fault grooves) and fault polish on a chunk of sandstone in far western Texas.
Friday fold: ice in Iceland
Searching for Peter Luffi’s latest Where On Google Earth? challenge, I found myself touring Iceland last week. While I didn’t find the strange comet-shaped feature he posted, I did find this: And zooming in a bit, to the high-contrast area in the center: This appears to be volcanic ash layers distorted by glacial flow and … Read more
New year’s atop Lion’s Head
My first view of Lion’s Head, the little butte northwest of Table Mountain, came through the fog on the morning that Evelyn and Jackie took Lily and I to Sea Point to see the migmatite: A lofty pinnacle – made of the same flat-lying quartz sandstone as the mesa of Table Mountain to the southeast: … Read more
Hanksite and other wonders of Searles Lake
Callan’s field studies class journeys to Searles Lake, California, a playa rich in evaporite minerals both prosaic and exotic.
Tafoni weathering of Malmesbury Group turbidites
Some tafoni (pattern of little weathering pits) expressed on Malmesbury Group (~700 Ma) turbidite sandstones at a little outcrop on the eastern shore of False Bay, South Africa: That last one seems to have some concentric layering to the tafoni pits – exfoliation? Spheroidal weathering? Hmm…
Malmesbury Group sediments on the eastern side of False Bay
In December, Callan found an outcrop of Neoproterozoic-aged turbidites in South Africa, on the eastern shore of False Bay.
Friday fold: a tortured tempestite
Hand sample of folded limestone strata in West Virginia (presumably Devonian in age). Note the rip-up clasts and large grain size at the base of the sample (to the right in the photo). Note the fine-grained, thin-bedded shale laminations towards the top (left) of the sample, too. Together, they tell a story of decreasing energy … Read more
Plane views
Here are some photos out the window of my flight home from California the week before last… Snow on the north sides of mountains, but not on the south sides (view is from the south towards the north): Same thing here: And again… And again… it would appear that our route from Reno to Minneapolis … Read more
More folds from the White Mountains
I know we spent time last Friday on some nice folds in the Poleta (?) Formation in the White Mountains of California, but here are a few more that I saw on my way up to the Ancient Bristlecone Pine Forest… Some elliptical objects caught my eye: Traced out along the plane of bedding, these … Read more
Eruption column in Owens Valley :)
I’ve been showing a lot of photos lately from my field course’s trip up into the White Mountains. While we were driving up the road from Westgard Pass to the Ancient Bristlecone Pine Forest, we saw something interesting going on in the southern Owens Valley. Take a look at this view to the southwest, from … Read more
Overturned bedding in Poleta (?) Formation, White Mountains, California
After a roadside explanation just an hour and a half earlier on how the relationship between bedding and cleavage can reveal whether bedding is likely right-side-up or up-side-down, my students and I were walking up the road to the Ancient Bristlecone Pine Forest in the White Mountains of California, and I saw this outcrop that … Read more