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12 November 2010
Friday fold: blueschist
Lately, this blog has been focusing a lot on a subduction zone complex in Turkey, the Tavşanlı Zone. Much of the geologic appeal of that complex is its profusion of high-pressure, low-temperature metamorphic rocks, those in the blueschist metamorphic facies. From the last location visited on the Tavşanlı Zone field trip, I collected this fine sample: The penny is to provide a sense of scale. You’re looking at an oblique …
11 November 2010
Microfaults-a-million
I got to Pittsburgh around 1:30pm yesterday, which meant I had several free hours before the opening reception for new Fine Fellows. I took a bunch of photos of the exhibits there, but my traveling laptop doesn’t have the image processing software that I usually employ to resize these things, so for now I’ll just share this one. It’s a sandstone from South Dakota, age unknown, which shows beautiful parallel …
10 November 2010
Gigapanning 101
I’m off today to the first ever Fine International Conference on Gigapixel Imaging for Science, held in Pittsburgh, Pennsylvania over the next several days. There, as one of this year’s cadre of Fine fellows, I’ll be given a Gigapan camera robot and photo-stitching software, and they will train me how to use it. I’m looking forward to producing my own Gigapan images, which will doubtless be primarily geological in scope, …
8 November 2010
Tavşanlı Zone field trip, part 6
Part 5 of the Tavşanlı Zone field trip left us eating lunch amid some fine blueschists. Of course, nothing tops off a blueschist lunch like… more blueschist. So after our meal, we took another stroll through the countryside in search of more interesting subduction zone rocks… I’;ve got a bunch more photos for you today. Let’s start with this fine “schisty” example of a blueschist, with big needles of glaucophane …
5 November 2010
Friday fold: a gummy worm
A week ago today, I went out on the Billy Goat Trail (near Potomac, Maryland) with a group of students: five from George Mason University’s GeoClub, and two that are current Physical Geology Honors students with me at Northern Virginia Community College. One of my students, Robin, observed this lovely fold, and called my attention to its gummy-worm-like form. When we saw it, we all knew it was destined to …
3 November 2010
Tavşanlı Zone field trip, part 5
After our mind-boggling encounter with the limestone strata turned lurid pink by their high-pressure encounter with subduction, our band of merry geologists set off for a stroll: We began the walk in greenschist + blueschist mélange, as seen here with a Turkish 1-lira coin (26 mm diameter; about the same size as a U.S. quarter) for scale: Then we crossed a structural contact into an ophiolitic mélange thrust sheet, a …
2 November 2010
That’s what you call a conchoidal fracture
Obsidian bearing well-developed conchoidal (clam-shell-shaped) fracture with concentric ribs, as displayed at the recent U.S. Science and Engineering Festival on the National Mall by a local gem/fossil/mineral club.
1 November 2010
Tavşanlı Zone field trip, part 4
Picking up where we left off… I was telling you about the field trip I took through Turkey’s Tavşanlı Zone, a tectonic suture zone between fragments of continental crust that accreted during the closure of the Tethys Ocean. Day 2 of the trip dawned and we broke fast, and then headed out to a bizarre locality, an exposure of the accretionary complex near the village of Gümüşyeniköy. This is a …
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.