Callan Bentley In the interest of conveying a sense of the sort of stuff that goes on a large science conference like the AGU Fall Meeting, I’ll resume my narrative where I left off with yesterday’s description. I began by swinging by the press room where I grabbed a complimentary breakfast, then headed down to the “early … Read more
I got to San Francisco on Saturday afternoon, flying in on the same flight from DC as Rob Simmon and Maria-José Viñas. MJ and I took the BART downtown, and then met up with Jess Ball for Thai dinner and a yummy dessert of banana wrapped in roti with Nutella and coconut ice cream. Then, … Read more
From “Volcanic Versus Anthropogenic Carbon Dioxide” by Terry Gerlach in the June 14, 2011 issue of EOS: Human activities emit ~135 times as much carbon dioxide as the world’s volcanoes? Holy cow.
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 … Read more
I got this e-mail this morning from a geology colleague. I’ve despecified it and made it gender-neutral: I have a silly question about word usage and I’d love to hear your opinion. Today I overhead [a biologist colleague] talking about continental drift, and I cringed. S/he used it in context with continents moving apart and … Read more
More pillow-like structures, seen in the Catoctin Formation, on the west side of the Blue Ridge Parkway about ten miles south of Interstate 64. Mini Sharpie for scale – what do you think? They don’t seem to be as strongly fracture-controlled as the Stony Man area “pillows.” But dang, they sure are small… Read the … Read more
Sorry to be late with this – I think that’s the first time I’ve forgotten to post a Friday fold. Blame it on the tryptophan.
On our way up Compton Peak the other day, my field crew spotted some fibrous growths of ice growing up and out of the ground (perpendicular to the surface of the mountain): (Joe’s hand lens for scale.) The fibrous habit made me think of asbestos, and then I wondered whether the different shapes of ice … Read more
Callan and three students visit a world-class outcrop of columnar jointing in Shenandoah National Park.
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 … Read more
Callan visits a new outcrop of highly-sheared rocks in the basement complex of Virginia’s Blue Ridge province.
Other members of the geoblogosphere have been posting brief image-heavy missives on labradorite over the past 24 hours. Collectively, they remind me that I’ve got a backlog of photos from the Adirondacks of upstate New York to share. Here are a few scans of cut and polished cobbles of the anorthosite from the Adirondack Massif, … Read more
I saw this boulder lining a garden this past weekend down in Nellysford, Virginia, in the scenic valley of the Rockfish River draining the eastern slope of the Blue Ridge. It’s a piece of the Neoproterozoic-aged Catoctin Formation, a series of lava flows and associated rocks that erupted on the breakup of the early supercontinent … Read more
Happening on campus, right now:
Today, I share with you eight images that I took yesterday on Skyline Drive in Shenandoah National Park: Blocks of Antietam Formation quartzite (meta-quartz sandstone) of Cambrian age, used in the low rock walls of an overlook parking pull-out. They all bear lovely Skolithos trace fossils (seen end-on, and in cross-section):
After my talk Wednesday night to the Potomac Appalachian Trail Club, I got an email from PATC member Tom Johnson, with an extraordinary photo attached. It shows an exceptional outcrop of the Neoproterozoic Catoctin Formation, exposed atop Compton Peak in northern Shenandoah National Park, Virginia. The outcrop features enormous, well-preserved cooling columns from these ancient … Read more
At last weekend’s gala banquet to celebrate the 50th anniversary of the William & Mary geology department, I was tickled to see that the centerpiece for each table was a rock of some sort. I spotted Gore Mountain Amphibolite, Baker Mountain Kyanite, brachiopod fossils in limestone, a fossil whale vertebra, a chunk of Aquia Creek … Read more
Continuing now with the discussion of my pre-GSA meeting field trip to examine the structural geology of the Quetico-Wabigoon subprovince boundary within the Superior Craton of southern Ontario, Canada. Our penultimate stop on the second day of the trip was a roadcut exposing the gabbro of the Grassy Portage Sill. This is what it looks … Read more
The geology program at the College of William & Mary turned 50 years old this year, and last weekend they held a party to celebrate. Of the 800 or so geology majors the department has produced in 50 years, about 100 came to this event – that’s a pretty great ratio, I think: 1 out … Read more
Here’s a piece of vein quartz with a series of interesting “cubist disc” shaped holes in it. I interpret these cavities as external molds of some mineral which has now been physically removed or chemically weathered away. So only its exterior shape remains, and I wonder if that’s enough to identify the mineral that used … Read more