For the first time ever, I have won a Where on Google Earth? that Ron Schott hosted, heavy on the clues. Now that it’s my turn to host, I’d like to spice things up a bit with a dynamic view. Using Google Earth’s historical imagery feature (the little “clock” button up top), I managed to … Read more
One of my students wrote to me this morning with a question about the relationship between bedding, cleavage, and folding. He asked: I am not sure how we use the relationship between bedding and cleavage to interpret fold limbs. It seems if bedding is near vertical and cleavage is closer to horizontal, this would be … Read more
The Lilster and I caught John McPhee give a reading tonight at our local uber-cool bookstore. Check it: First time I’ve seen McPhee live. Great stuff!
The first time I went to the Billy Goat Trail (Potomac, Maryland) with geology as the goal (as opposed to mere recreation), it was 2002. The trip was led by a professor at the University of Maryland. I was a graduate T.A. then, and didn’t know anything about the local geology. I remember at the … Read more
It’s a rough life, working in the places I have to work… here are a few photos from yesterday’s field trip on the Billy Goat Trail with my NOVA Physical Geology students. Photos are courtesy Dr. Meg Coleman, who joined us for the hike. A post-lunch lecture on river incision (note the two prominent bedrock … Read more
Almost a year ago, on my old blog, I brought up the issue of the Suess effect. Go read that post if you don’t remember what the Suess effect is. If you want an executive summary, digest this: The burning of low-14C fossil fuels (because the fuels are old and the 14C has all decayed), … Read more
A quick post to share a few images of an outcrop I visited last September out in California’s Owens Valley. This is a spot where alluvial fans coming off the eastern Sierra Nevada were overrun by a basaltic lava flow (Jeff, Kim, Fred, and Kurt for scale): The unofficial term for these conglomerates deposited by … Read more
Sunday morning, NOVA adjunct geology instructor Chris Khourey and I went out to Sugarloaf Mountain, near Comus, Maryland, to poke around and assess the geology. Sugarloaf is so named because it’s “held up” by erosion-resistant quartzite. It’s often dubbed “the only mountain in the Piedmont,” which refers to the Piedmont physiographic province. Here’s a map, … Read more
On the transect trip, I also saw some nice meso-scale “minor” structures that probably formed during Alleghanian deformation. Prominent among the ones that really impressed me were these en echelon tension gash arrays, deforming the Antietam Formation quartz sandstone and well exposed in blocks used to construct the wall along Skyline Drive and the Sandy … Read more
This month’s Accretionary Wedge is being hosted by Ed over at Geology Happens. Ed asks the rest of us a simple question, “What are you working on now?” Gosh, where to start? It’s a busy time for me, but then again, it almost always is. I spent last week immersed in the NE/SE GSA section … Read more