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19 November 2010
Is this an angular unconformity on Mars?
Jason Buchheim, one of the people I met last week in Pittsburgh, just posted a Gigapan of images stitched together from the Mars Observer MER HiRise. Part of it jumped out at me as being similar to the map pattern we see on Earth where an angular unconformity outcrops: Here, I’ve highlighted the pattern which caught my eye: On the other hand, the increasing inflection of the “lower” (in the …
29 October 2010
Geology of the Richmond area field trip
On Saturday, after a fruitful 24 hours at the VCCS Science Peer Conference, my colleague Pete Berquist (of Thomas Nelson Community College) and I led a field trip to examine the geology of the Richmond, Virginia, area. We were joined by seven of our VCCS science-teaching colleagues and author Lisa Starr, a speaker at the conference. We started off by driving down to Belle Isle, an island located on the …
17 October 2010
Birthing a litter of drumlins
Quite appropriately, Glacial Till won the new the latest edition of “Where on (Google) Earth?”, hosted here yesterday. The location I picked is the subject of a new paper by Mark Johnson and colleagues appears in the current issue of Geology (October 2010). It shows a place in Iceland where a piedmont-style outlet glacier called Múlajökull is pooching out to the southeast from the Hofsjökull ice cap. Here’s a more …
24 September 2010
Friday fold: Siccar Point, Scotland
As with last week, I’m going to show you someone else’s fold today. This one should have strong resonance with most geologists, because it’s a fold in the tilted (and contorted) older strata exposed below the famous unconformity at Siccar Point, Scotland: I found this image on the British Geological Survey’s online repository of images, which are available for public use with attribution. I found out about the BGS photo …
6 May 2010
"Those aren't pillows!"
In the 1987 comedy Planes, Trains, and Automobiles, John Candy and Steve Martin have a funny experience. It involves a cozy hotel room (one bed only) and the two travelers are huddled up for warmth. As he wakes up, John Candy thinks he is warming his hand “between two pillows.” At hearing this, Steve Martin’s eyes pop wide open, and he yells, “Those aren’t pillows!” They jump up, totally discombobulated. …
26 April 2010
3,2,1, Contact!
On my structure field trip just over a week ago, we found the contact between the Mesoproterozoic-aged Blue Ridge basement complex and the overlying Neoproterozoic Catoctin flood basalts (now metamorphosed to greenstone). This nonconformity can be found just west of the Appalachian Trail at the Little Stony Man parking area in Shenandoah National Park. Here’s four photos, with my left index finger for scale, in raw and annotated versions: It’s …
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.