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 … Read more
The Lilster & I drove out to Harpers Ferry, West Virginia, today, and crossed the Potomac River to hike up to the overlook at “Maryland Heights,” which is what they call the Blue Ridge north of the river. On the way uphill, I noticed this nice example of Harpers Formation bedding and cleavage dipping in … Read more
Heat-stressed map of the Chesapeake Bay / Washington, DC region, as seen at Kenilworth Aquatic Gardens. Looks like mudcracks, eh? Similar stresses; similar strains.
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
Yesterday, I took my GMU structural geology class to the Billy Goat Trail, my favorite local spot for intriguing geology. Unlike last year, we managed our time well enough that we got to clamber around on the rocks downstream of the amphibolite contact. Here’s Sarah, Lara, Kristen, and Alan, negotiating a steep section: Justin, Joe, … 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
Just got back from three days of geology conferencing at the Northeastern & Southeastern Joint Section Meeting of the Geological Society of America in Baltimore. No time to blog whilst there, though I shot a dozen or so tweets up to my Twitter feed: small beer compared to a nice meaty blog post. Apologies if … Read more
Check out these cool structures in one of the amphibolite bodies exposed along the Billy Goat Trail (C&O Canal NHP, near Potomac, Maryland): Those are shear bands — basically small shear zones that are discretely localized within a larger body of less-deformed rock. Note the grain-size reduction visible in the shear bands, their dextral sense … Read more