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2 December 2011
Friday folds (and boudinage): Superior Craton day 3, stop 1
Today the Friday fold comes with copious bonus structures. It’s the first stop we hit on Day 3 of the pre-GSA Minneapolis field trip to examine the structural geology of the subprovince boundaries within the Superior Craton. This particular site showed granitoid dikes that had been deformed during dextral transpression into a variety of structures depending on their initial orientation, pre-deformation. Those with orientations parallel to the maximum extension direction …
18 November 2011
Friday fold: mafic metavolcanics
Okay – in spite of numerous distractions (see every other post so far this week), it’s time to return to the pre-GSA Minneapolis structural geology field trip. Our final stop of the second day in the field was a series of folded up mafic metavolcanics. I’ve got some photographs of them. These mafic volcanics were strained in a relatively incompetent (weak) fashion between two more competent (stiff) gneiss domes in …
7 November 2011
Pseudoboudins!
You may recall that I kind of like boudinage. So it piqued my interest when our field trip leaders (on the pre-GSA Minneapolis trip to examine the structural geology of the sub-province boundaries in the Superior Craton) said our next stop was to visit “pseudoboudins,” segments of granitoid pegmatites that looked like boudins but probably represented a totally different process. Here’s the idea: With regular old boudinage, the solidification of …
1 November 2011
Geoblogs as a device for student engagement
Here’s the talk I gave at GSA last month: [youtube=”http://www.youtube.com/watch?v=oXt5aZIu5Xk”] It’s presented here at a slower pace than the actual talk was, since I didn’t have to run and catch a plane 45 minutes after presenting it, but there are some PowerPoint bugs with some of the animations. Oh well – recording it and putting it online is more than 99.9% of GSA presenters ever do to share their …
27 October 2011
Pavement outcrops of strained Seine conglomerate
Picking up from the astonishing first couple of outcrops we saw of strained Seine Group metaconglomerate from the boundary between the Wabigoon and Quetico sub-provinces of the Superior Craton, our group moved on down the road. It was lovely clear fall weather near Fort Frances, and shockingly warm. Our third stop of the morning was a lunch stop atop a great “pavement” outcrop of the same strained metaconglomerate, showing different …
12 October 2011
The GSA meeting experience, 2011
I’m on the plane home from the annual meeting of the Geological Society of America, held this year in Minneapolis, Minnesota. This annual event features a robust smorgasbord of science, with talks and posters detailing the research efforts of thousands of geoscientists from the US and other countries. It’s an amazing experience on many, many levels, and as I fly home now after a week in Minnesota, my feelings are …
26 October 2010
Tavşanlı Zone field trip, part 3
Picking up where we left off last time, we were in some partly-serpentenized peridotite, part of the Burham Ophiolite in Turkey’s Tavşanlı Zone, an ancient tectonic suture. Our next stop on the field trip allowed us to visit some diabase dikes: Here’s a close-up of the right contact of the dike with the host peridotite: The field notebook’s long edge is ~18 cm. And here it is again, annotated: Near …
24 March 2010
Transect debrief 4: transgression, passive margin
…So where were we? Ahh, yes: an orogeny, and then some rifting. What happened next to Virginia and West Virginia? Let’s consult the column… After the rifting event opened up the Iapetus Ocean, seafloor spreading took place and tacked fresh oceanic crust onto the margin of the ancestral North American continent. As North America (“Laurentia”) moved away from other continental fragments (Congo craton, Amazonia craton), it got a little bit …
20 March 2010
Transect debrief 1: starting in the basement
It is time to debrief the post-NE/SE-GSA field trip that I went on, affectionately dubbed the “Transect Trip” for the past 27 iPhone-uploaded “live”-geoblogged posts. First off, I’d have to say that I enjoyed the live-field-blogging experiment overall, though I’ve got some critiques of the process and products. I think it’s amazing that I can upload photos and short blog posts from my iPhone to this site with a minimum …
18 March 2010
Transect Trip 27: fluvial overbank deposits
Over on the far right by Chuck Bailey (yellow shirt) you can see the crescent-shaped profile of a river channel (gray color). To the left of that, you can see levee deposits, and beyond that (to the left) crevasse splay deposits and the floodplain (dark red mudstones). This is in the Hampshire Formation, part of the Acadian “clastic wedge.”
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.