You are browsing the archive for 2018 April.
27 April 2018
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!
25 April 2018
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.”
24 April 2018
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 something along the lines of “since there are 5 billion people in the world, a …
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 end-Cretaceous extinction. So last week I read T. rex and the Crater of Doom (1997). …
20 April 2018
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.
18 April 2018
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.
13 April 2018
The Friday fold is on display in a rock garden outside the Department of Earth and Environmental Sciences at the University of Kentucky.
10 April 2018
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.
9 April 2018
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 photos I took of these orthocones, all on pavement exposures (horizontal bedding planes) with my …
6 April 2018
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 of the canyon occupied by the Root Glacier, several kilometers NW of McCarthy, Alaska. The …