Callan Bentley A million years ago, I posted about my inaugural attempt to use the Butter Buster to illustrate shear zone deformation to my structural geology students. Today, using the UnFREEz program to make an animated GIF (Thanks, Lockwood!), I give you the Butter Buster animation:
Here’s a sample from my 2004 geology M.S. thesis work in the Sierra Crest Shear Zone of eastern California. The rock is a sheared ignimbrite (ashflow tuff) tuff bearing a porphyritic texture and a nicely-developed “S-C” fabric. With annotations, showing the S- and C-surfaces, and my kinematic interpretation: S-C fabrics develop in transpressional shear zones: … Read more
There is an old Chinese aphorism that “the beginning of wisdom is to call things by their proper names.” One of the naming conventions that tends to trip up NOVA students who hike the Billy Goat Trail with me is the difference between a “terrace” and a “strath.” This morning, I created a graphic that … Read more
“The Geotaggers’ World Atlas #8: Washington, DC” by Eric Fischer If you like maps, you should go check out these images by photographer Eric Fischer. (via here) The different colors represent different modes of transportation: Black is walking (less than 7mph), red is bicycling or equivalent speed (less than 19mph), blue is motor vehicles on … Read more
In January, a large landslide occurred in the Hunza Valley of Pakistan’s Karakoram Range, near the village of Attabad. Like the Madison River landslide in Montana (1959), or the Gros Ventre landslide in Wyoming (1925), a river was dammed by the slide debris, and the impounded waters began to rise. At Gros Ventre, the landslide-dammed … Read more
…. And on the other side, we have secondary (tectonic) structures, focused on folds and faults:
One of the things I managed this week was to fill up a new display case in our Student Study area with a structural geology display. On one side is primary structures, both igneous and sedimentary….
In today’s post, I’ll finish up with my geologic discussion of the falls of the James River in Richmond Virginia, south of Belle Isle. Previously, we’ve examined the bedrock at this location (the Petersburg Granite) and a series of fractures – some faults and some extensional joints – that deform that granite. Now we come … Read more
In my previous post, I introduced you to the Petersburg Granite, as it is exposed south of Belle Isle, at the falls of the James River in Richmond, Virginia. I mentioned that it was fractured, and I’d like to take a closer look at those fractures today. The geologically-imparted fractures were exploited by human granite … Read more
Last Friday, NOVA colleague Victor Zabielski and I traveled down to Richmond, Virginia, to meet up with Chuck Bailey of the College of William & Mary, and do a little field work on the rocks exposed by the James River. Our destination was Belle Isle, a whaleback-shaped island where granite has been quarried for dimension … Read more
I mentioned going out in the field last Thursday with Liz Johnson‘s “Geology of Skyline Drive” lab course at James Madison University. We started the trip south of Elkton, Virginia, at an exposure where Liz had the students collect hand samples and sketch their key features. Here’s one that I picked up: Regular readers will … Read more
This weekend I went camping with my family in Virginia’s Shenandoah Valley, near Berryville. I poked around with river cobbles and experienced fluvial dynamics firsthand with an inner tube ride down the Shenandoah River, but mainly I turned off the geology part of my brain. Instead, the brain enjoyed idling, and thinking about how to … Read more
I realize the geological blogging has been rather light around these parts lately – just one more day of “fluff” posts… Here’s a damselfly, photographed close-up last Thursday along Route 340 south of Elkton, Virginia. There were also some rocks there… more on them tomorrow.
Spent the day in the field yesterday with Liz Johnson of James Madison University and her fun group of students in a “Geology of Skyline Drive” summer course. More on the geology later… For now, I just wanted to toss a group of photos of poison ivy up here. Look at this beautiful plant! Look, … Read more
Searching around for the current Where on Google Earth, I found this astonishing place in western New Zealand: That’s Mount Taranaki, and evidently the vegetation change you see in the circular colored shape around the mountain must be due to a protected-area boundary. Check out the radial drainage pattern on that sucker! Check it out … Read more
My cat Lola has a thing for big sheets of paper, particularly maps. Here she is this morning, “helping” me plan a summer trip to Turkey:
In honor of Mother’s Day, I offer up an unusual bouquet of flowers… These are not really flowers, of course, but an odd form of lichen that I found in the Crazy Mountains of Montana last summer, growing on a spruce tree. Freaky little things, eh? All shots are with the macro function on: the … Read more
Ever since I saw this at Microecos and Myrmecos, the staff here at “Mountainecos” have been wanting to try it out. Behold my first three iPhone photos supplemented by a hand lens (Belomo triplet, at a distance of about 1.5 cm from the subjects): That’s a trilobite and a penny, by the way. Try it … Read more
The following letter, signed by 255 members of the National Academy of Science, appears in the current issue of the journal Science. I wholeheartedly concur with the content of this letter, and republish it here in the interest of getting its message out to the world. Please take the next four minutes of your life … Read more
In the 1987 comedy Planes, Trains, and Automobiles, John Candy and Steve Martin have a funny experience. It involves a cozy hotel room (one bed only) and the two travelers are huddled up for warmth. As he wakes up, John Candy thinks he is warming his hand “between two pillows.” At hearing this, Steve Martin’s … Read more