You are browsing the archive for November 2016 - Mountain Beltway.
30 November 2016
“Drumsticks” of Islay tillite
One fun thing about examining the Port Askaig Tillite in the field is to find odd-shaped exemplars of the unit lying on Islay’s beaches. My favorites were shaped like wands, or antennae, or perhaps the drumsticks freshly detached from a Thanksgiving turkey… a big clast at one end and then a thin septum of the finer-grained matrix to hang on to: Here’s an example: The shape results from differential weathering …
29 November 2016
Islay’s Port Askaig tillite
The Port Askaig Tillite is a Neoproterozoic diamictite on the eastern shore of Islay (Scotland) that may record a “Snowball Earth” glaciation.
28 November 2016
Scenes from the Wildlife Camera
Here’s a look at some of the wild critters that have been visiting my yard this year: [youtube=”https://www.youtube.com/watch?v=hh8muzLOE54″] The video’s organized in alphabetical order, so it starts with bears, and ends with a walking stick insect. See how many you can identify! Plus, here’s a compilation of 125 still photos of black bears from June of 2015: [youtube=”https://www.youtube.com/watch?v=JBkFUQ_igmU”]
25 November 2016
Friday fold: intrafolial folds in Eriboll mylonite
At the birthplace of the term “mylonite,” we can find Friday folds hidden in the foliation.
24 November 2016
U-turn
Scotland was glaciated during the Pleistocene “Ice Ages:” The signatures of glaciation are manifold in a scene like this. Most prominent and easily recognizable is the broad, relatively flat-bottomed U-shaped valley. Now check this one out: That’s a U-turn in a U-shaped valley: the valley is first gouged to the right, then turning around and heading in almost the reverse direction: Good things these things flow so slow, otherwise that …
23 November 2016
A conversation with Zack Labe
Yesterday, I mentioned climate change visualizer extraordinaire Zack Labe. As delineated then, he’s a PhD student at U.C. – Irvine in the Earth Systems Science department. He’s producing some really excellent #dataviz on climate change. Today, I’d like to share a short exchange I had with Zack about his work. 1) Please give Mountain Beltway readers a sense of your background, leading up to what you’re working on …
22 November 2016
We are in unprecedented territory with global sea ice
The amount of sea ice on planet Earth is much, much lower than ever recorded at this time of year. Will this anomaly turn out to be a relatively minor “weather” event? Or is this what a sea ice tipping point looks like?
21 November 2016
GIGAmacro sample preparation: 3 techniques
Here are three pairs of GIGAmacro images to illustrate a few techniques I’ve used in preparing the samples and the images. The image pairs here illustrate the effects of transparent acrylic coatings, pressure-washing, and post-imaging clean-up in Photoshop. Let’s begin with a meta-ignimbrite of the Catoctin Formation, cut with a rock saw and polished using a handheld grinding wheel with diamond grit pads, and then with one of the two …
18 November 2016
Friday fold: Lewisian gneiss near Tarbet
I tried something new this morning, and polled Twitter for their choice of Friday fold: Quick poll – What do you want for the Friday fold? 30 minutes to respond. — Callan Bentley (@callanbentley) November 18, 2016 As of the time of this posting, the first choice, “Lewisian gneiss @ Tarbet” won out with 7 / 10 votes. The people have spoken, and this time I like the result of …
17 November 2016
A pocketful of podcasts
I listen to a few podcasts, and I’ve been meaning for a long time to write down some thoughts about them to share, in the same spirit in which I review books, or less frequently movies or television programs. First, a general comment: I really, really like podcasts. This is a medium that is unique (aside from radio) in its ability to get you to think while you’re doing something …
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.