Cross-bedding in Archean komatiitic ash deposits
Cross-bedding isn’t just for modern sedimentary deposits; you can find it in truly ancient ash deposits too! Let’s head to South Africa and take a look.
Losing Ron and Declan
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 … Read more
Friday fold: a quartet from Marli Miller’s website
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 … Read more
Friday fold: 3D model of intense folding
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.
Friday fold: Corsican blueschist sheath fold
The Friday fold takes us to the French Mediterranean island of Corsica. Are you ready to dip into the blueschist facies in search of sheath folds?
A Most Improbable Journey, by Walter Alvarez
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 … Read more
Last Stand, by Michael Punke
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 … Read more
2/3 pass rate on determining geopetal “up”
A visual challenge via Twitter to determine stratigraphic younging direction ends with equivocal results. So let’s use GIGAmacro imagery to school your sedimentological students on how three primary sedimentary structures look different right-side-up versus up-side-down.
Friday fold: Cape Liptrap
Sandra McLaren of the University of Melbourne is the source of today’s guest Friday Fold. Let’s join her on a journey with her students to Cape Liptrap (southeast of Melbourne in Victoria, Australia) on a lovely day: What a spectacular place. (We have featured folds from this site previously.) Happy Friday all!
Natural Bridge State Resort Park, Kentucky
A visit to a natural sandstone arch (or “bridge” as the locals call it) in eastern Kentucky yields unexpected bonuses, like fossil wood, Liesegang banding, and the honeycomb-like weathering pattern called “tafoni.”
An astonishing rise in the number of humans
One interesting thing about reading T. rex and the Crater of Doom, by Walter Alvarez in 2018 is the change in world population since it was first published in 1997. In explaining to his readers how to think about measurements in “parts per billion,” Alvarez explains his mental shortcut to appreciating those numbers. He says … Read more
T. rex and the Crater of Doom, by Walter Alvarez
Walter Alvarez has a new book out, and its publication reminded me that though I read and appreciated The Mountains of St. Francis, I had never read his most famous work — the account of how he and his father and a team of other researchers zeroed in on an extraterrestrial impact explanation for the … Read more
Friday fold: Isoclinal in Damaraland
A guest Friday fold from Graham Andrews of West Virginia University: Graham describes this as an almost along axis view of a huge isocline in the Damaraland belt, Namibia Thanks for sharing! And a happy Friday to all.
Visiting St. Francis’s lovely limestone
The Cretaceous-Paleogene limestone called Scaglia Rossa was used to construct a basilica in tribute to St. Francis. Let’s head to Assisi and take a look.
Friday fold: Blue Ridge gneiss in the University of Kentucky rock garden
The Friday fold is on display in a rock garden outside the Department of Earth and Environmental Sciences at the University of Kentucky.
An outcrop showcasing a strand of the Kentucky River Fault System
Roadcuts in Kentucky show Ordovician limestones of two distinct types, replete with fossils and primary sedimentary structures, and juxtaposed by a fault, one strand in the Kentucky River Fault System.
Orthocone nautiloids of the Lexington Limestone
I took a trip last week to Kentucky. My colleague Kent Ratajeski from the University of Kentucky took me out on a nice all-day field trip to examine some of the local geology. I was particularly impressed with the large straight nautiloid fossils that abounded in the Ordovician-aged Lexington Limestone. Here are a series of … Read more
Friday fold: “wrecumbent in Wrangellia”
Darrel Cowan of the University of Washington has pitched in a Friday fold. Check this lovely scene out: Darrel says this is a recumbent fold in the Upper Triassic Nizina and Chitistone limestones. I took the photo when I worked for Shell in 1973 or 1974. I’m pretty sure it is on the west wall … Read more
101 American fossil sites you’ve gotta see, by Albert B. Dickas
Mountain Press has released a new volume by frequent author Bert Dickas: it’s a compilation of 101 places in the United States where fossils can be viewed. Some sites are collection sites on public land; others are museums or protected areas. The book is a useful collection of information in a concise, well-illustrated form. Each … Read more
Friday fold: Recumbent Harpers
Stop the presses! This late-breaking Friday fold has just been submitted here at Friday Fold Headquarters. This is from Philip Prince/Virginia Division of Geology and Mineral Resources: It’s a recumbent fold of Harpers Formation metasandstone in the James River Face area. Pretty lovely exposure. This outcrop would make a good 3D model. Happy Friday to … Read more