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15 May 2020
Friday fold: Argentinian turbidites
Zoltán Sylvester brings us this Friday’s fold: And there’s more where that came from: These are deepwater strata of the Lower Cretaceous Rio Mayer Formation, exposed near Lago Argentino, Argentina, south of the lake’s northwest “arm,” about here. They were deformed so exquisitely during Andean mountain-building. Zoltán is a talented photographer, and you should check out more of his work here.
15 January 2019
Easing of selective pressure on Opuntia cacti in the Galapagos Islands
A cactus you can pet with your bare hand? Turns out it can tell you something about whether that island contains any land iguanas. A case study in the easing of natural selective pressure.
14 January 2019
A tale of three iguanas
As noted last week, I spent the week spanning New Year’s Eve in the enchanted isles of the Galapagos. The previous week (over Christmas) my family and I were in coastal Ecuador. I saw a total of three species of iguanas in the two locations, and they offer a neat little story of evolution. Let’s take a look. First, let’s introduce the key players: The green iguana, Iguana iguana (coastal Ecuador, …
8 January 2019
Geology of the Galapagos Islands
Dozens of delectable geological images from the Galapagos Islands, showing fluid basalt flows and violent pyroclastic deposits along with many primary volcanic features (and a bit of sedimentology thrown in for good measure).
26 January 2018
Friday fold: eastern Andes
This image graces the cover of the new report, Challenges and opportunities for research in tectonics: Understanding deformation and the processes that link Earth systems, from geologic time to human time. A community vision document submitted to the U.S. National Science Foundation: Make it bigger by clicking it The photo is of a landscape in the Eastern Cordillera of the Andes, southern Peru, showing folded Permian carbonates cut by a …
21 April 2016
Firsthand reports from Canoa, Ecuador after the quake
Callan’s mother-in-law lives in one of the most strongly-shaken regions of Ecuador. Here, she and her boyfriend recount the experience of the earthquake Saturday night and its aftermath. Includes 8 photos from the scene.
7 April 2016
New GIGAmacro images of rock samples
Another week, another batch of new images produced on my home-based Magnify2 imaging system from GIGAmacro. Leptaena brachiopod in (Mississippian?) limestone from Montana: Link Here’s the flip side of the same sample, with a lot of fenestrate bryozoans to see: Link Fault breccia from the Corona Heights Fault of San Francisco: Link Amygdular metabasalt from the western Sierra Nevada of California: Link Araucaria mirabilis gymnosperm cone fossil, from the Cerro …
20 March 2016
3D and GIGAmacro views of Cerro Toro conglomerate
Six years ago, I went to Patagonia*, and collected this sample there. It’s a deep-water conglomerate from the Cerro Toro Formation. I’ve imaged it here in two media: the Sketchfab-hosted (Photoscan-generated) 3D model, and GigaPan-hosted (GIGAmacro-generated) views of both the front and the back. In combination, these three digital items can probably give you a pretty good sense of the sample: Link Link _______________________ * In case you missed it …
2 March 2016
The Invention of Nature: Alexander von Humboldt’s New World, by Andrea Wulf
This is the second Andrea Wulf book I’ve read in the past month. It’s a biography of a great naturalist and popularizer of science and travel writing, who at the same time is largely forgotten in the modern English speaking world. Alexander von Humboldt’s intellectual impact is vast, Wulf argues, leading to everything from Darwin’s wanderlust (and thus, to the observations that led to the idea of descent with modification …
27 March 2015
Friday fold: Isla Escarpada, Chile
I’m very nearly delinquent on posting the Friday fold… Here you go – a Google Earth view of a differentially-weathered fold partly above and partly below sea level in Chilean Patagonia, south of Puerto Natales: They call it Isla Escarpada. Awesome. Here’s a Google Maps link if you want to explore it yourself. Happy Friday!
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.