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29 May 2012
Snowball students visit the University of Maryland
The final meeting of my spring semester Snowball Earth class was a field trip to the University of Maryland, hosted by Snowball guru Jay Kaufman, a specialist in chemostratigraphy using stable isotopes. Here, Jay welcomes the class to his wet lab: Doing chemostratigraphy takes lots of samples. Here’s a drawer full of samples from one of Jay’s many field areas: Then it was time for show and tell. Jay brought …
14 May 2012
Hiking Cory Pass
Callan and his wife hike Cory Pass in Banff National Park, Canada, and encounter some geology, some solitude, and a spectacular landscape.
10 May 2012
Veiled geology at Naked Creek
As I mentioned, Monday had me out in the field, looking at the western Blue Ridge and eastern Valley & Ridge provinces in Virginia. This was a field review for the new geologic map of the Elkton East quadrangle by Chelsea Jenkins, Chuck Bailey, Mary Cox, and Grace Dawson. Immediately after lunch, we visited an outcrop in the middle of Naked Creek. You’ll be happy to hear that we all …
11 April 2012
Blue Ridge Thrust Fault field trip
One of Callan’s former students leads a field trip to examine the western edge of the Blue Ridge geologic province, attempting to answer the question of whether the Blue Ridge / Valley & Ridge contact is indeed the trace of a thrust fault. Breccias and S-C fabrics tell part of the story…
14 January 2012
Beach squiggles
One day in South Africa, Lily and I walked across Noordhoek Beach… Along the way, I noticed these little squiggles of sand: folded tube shapes. I decided I should photograph a few to share with Tony Martin, since he’s into trace fossils along coastal areas. Anyone have any idea what made these diminutive sculptures of sand?
15 November 2011
Skolithos in the sun
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):
4 October 2011
Tall tail
Okay, so I was out photographing ripples and admiring lichens, and then I saw this: That’s a rippled slab of sandstone, but with a linear groove that obliquely cross-cuts the ripple marks. Smaller, parallel grooves lie within the main groove. Here’s another look at that same one, spun around and zoomed-in: It looks as if something was dragged through the wet sand at this location, prior to its lithification. Given …
10 February 2011
Treasure trove of traces
Here’s an amazing sight that caught me unawares in Capadoccia — some paving stones outside a small “museum” (preserved Byzantine hoodoo church) that were chock full of some AMAZING trace fossils. Sense of scale is provided by a Turkish 1-lira coin, about the same size as a U.S. quarter. Check out the variety, size, and preservation quality of these gorgeous things: These are “negatives” — molds of depressions that were …
1 December 2010
The Konnarock Formation
A detailed description of one of the Virginia Blue Ridge’s most intriguing geologic formations: a maroon sedimentary sequence showing the advance of “Snowball Earth” glaciers in the Neoproterozoic.
14 October 2010
Rumeli Hisarı
Right after I got to Istanbul on this most recent trip, I took a taxi from my hotel down to the Bosphorus, to check out the Rumeli Hisarı, a fort complex built in 1452 by Sultan Mehmet the II in anticipation of the following year’s siege of Constantinople. It’s constructed at the narrowest point on the Bosphorus (660 m wide), with the aim of controlling boat traffic coming from the …
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.