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18 March 2013
Bouma ABE
The initials ABE might make you think of Lincoln, but that’s not what I’m talking about. Today, the letters mean something else: three subdivisions of the 5-part Bouma sequence of turbidites. I took these photos on a new (to me) outcrop of the Ordovician-aged Martinsburg Formation in Page County, Virginia. I visited the site for the first time last Thursday with GMU structural geologist John Singleton. We had been checking …
15 March 2013
Friday fold: a recumbent anticline in an abandoned quarry
Yesterday, I spent a pleasant day in the field with John Singleton, the new structural geology professor at George Mason University. I was showing John a couple of sites I’ve used as field trip locations for the GMU structural geology class, and John was showing a couple of new sites to me – places he visited on last fall’s Virginia Geological Field Conference. I missed VGFC last fall, as I …
Giant pencil cleavage in the Martinsburg Formation
Two giant “pencils” in the Martinsburg Formation: You can see smaller (more typically sized) “pencils” on the slope behind me. Photo by John Singleton, GMU.
12 March 2013
Five new GigaPans from Thoroughfare Gap
Yesterday, I took five new GigaPans at Thoroughfare Gap, a water gap where Broad Run cuts through Bull Run Mountain, the eastern limb of the Blue Ridge Anticlinorium at my latitude. The rocks here are the Cambrian-aged Chilhowee Group, with bedding tilted moderately to the east during Alleghanian mountain-building in the late Paleozoic. To the west is the crystalline core of this massive regional fold, and to the east is …
11 March 2013
Monday macrobug: Jumping spider
While the Monday Macrobug continues its official winter hiatus, we did have a fuzzy little jumping spider make an appearance in the house the other day: Did you see the @$#%ing ladybug hiding there in the background? Here’s a closer look at the spider: Jumping spiders are my favorite spiders – they seem like little mammals relative to the bulbous/spiky shapes that characterizes the spiders that I instinctually find so …
8 March 2013
Friday fold: Fault propagation fold from Cristo Rey
The Friday fold comes from the Texas – New Mexico – Chihuahua triple point, on the flanks of Cristo Rey mountain.
7 March 2013
Snow day aftermath
So we ended up getting 13 or 14 inches of snow yesterday. It was wet, and the temperature was right around freezing. As soon as it stopped falling, it started melting. One interesting aspect of this is that big wads of slushy snow were plopping off the trees every time a gust of wind came through. The structures these “plops” formed exhibit much of the same morphology of meteorite impact …
6 March 2013
Snow day II
There’s something so awesome about a heavy snowfall, so transformative – it really inspires me. I went out skiing this morning, and I’ve never seen our house looking more beautiful. The snow is about 11 inches deep so far: It’s a wet, heavy snow. Temperatures are hovering right around 32°F (0°C), so it’s sticking to everything. Our lower driveway: Our road: While I was skiing across the floodplain down by …
Snow day!
It’s lovely here in the Fort Valley this morning! Lily went skiing: Lola sat in the window: Yay!
5 March 2013
Documenting doomed outcrops: Scientists’ Cliffs, Maryland
The community of Scientists’ Cliffs in Maryland is a private community that happens to sit on some of the most amazing fossil exposures in the Coastal Plain. The strata in question are part of the Miocene-aged (~14 Ma) Calvert Formation. The Scientists’ Cliffs outcrops are better than the more famous outcrops at Calvert Cliffs State Park, mainly because of easier access. At the park, you have to hike in 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.