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14 March 2014
Friday fold: rolled boudin
Howard Allen returns with a Friday fold contribution for this week. He says: Not exactly a fold, but I thought you’d like this rolled boudin(?) (quartz) in a muscovite garnet schist (note garnets above the lens cap). This specimen is also from the Shuswap Metamorphic Complex, north of Sicamous, British Columbia. Lovely. Thanks for sharing, Howard!
9 March 2014
Off to Texas
I just wanted to let readers know that posting will be light this week, as I’m down in Texas running my field exchange course with Joshua Villalobos of El Paso Community College. Joshua’s supplying 12 students, and so am I. Together with talented colleagues, we’re aiming to give these students, many of whom hail from traditionally-underrepresented groups within the geosciences, a world-class field experience that will take them from the …
7 March 2014
Friday fold: Obsidian on display at ASU
Happy Friday! Here’s a beautiful folded obsidian sample, replete with conchoidal fractures, on display outside the geology department at Arizona State University in Tempe, where I was last week:
6 March 2014
Puzzling over the Wallbridge Unconformity along Corridor H
The Wallbridge Unconformity is a surface of stratigraphic hiatus or erosion between the depositional influence of the Tippecanoe and Kaskaskia epeiric seas. After Alan Pitts and I located ourselves in the Oriskany Sandstone (terminal Tippecanoe stratum), we looked stratigraphically above the quartz sandstone for the overlying unit, which should be the Needmore Formation shale (beginning of the Kaskaskia sequence). Indeed, the quartz sandstone was overlain by a black shale at …
5 March 2014
Oriskany Formation quartz arenite and its fossils, Corridor H
Today, a few more photos from the field trip last month to Corridor H, the fine new superhighway with so little traffic out in eastern West Virginia. Our antepenultimate stop of the day was at an outcrop we inferred should hold the Oriskany Sandstone, a Devonian quartz arenite that lies stratigraphically above the Helderberg Group limestones and below the Needmore Shale. We were using Lynn Fichter’s indispensible stratigraphic column for …
4 March 2014
God’s Harvard, by Hanna Rosin
I recently read God’s Harvard, by Washington Post reporter Hanna Rosin. It’s a profile of the people and philosophy behind Patrick Henry College, a private Christian college located not too far from me, in Purcellville, Virginia. PHC is an Evangelical place that strives to serve its homeschooled matriculating freshmen with a sense of worldliness and mastery of the liberal arts, so that by the time they graduate, they are equipped …
3 March 2014
Pieces of the beginning, via Chelyabinsk
A week ago today, I was in Tempe, Arizona, at Arizona State University, for a workshop on broadening participation (increasing diversity) in the geosciences. One of the neat things about ASU as a setting for this meeting is their enormous meteorite collection. I was particularly taken with the display of material from the extraordinary Chelyabinsk meteor detonation that occurred last year. ASU has pieces of glass from windows that were …
2 March 2014
A chip off the ol’ charnockite
We visited the Philip Carter Winery this weekend with family. Baxter and I were pleased to see outcrops of charnockite scattered over the property (located in the middle of the Blue Ridge geologic province). As any 18-month-old will tell you, charnockite is a pyroxene-bearing granitoid. It’s a distinctive and common rock type in Virginia’s Proterozoic basement complex. Here’s a close-up: The dark green is pyroxene. The white is plagioclase feldspar. …
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.