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13 February 2018
S-C fabric in limestone, Camerino, Italy
Some scaly Italian limestone shows off two foliations (S and C) which reveal the kinematic motions that built the Apennines.
2 February 2018
Friday fold: 3D model from the Portsoy Shear Zone
The Friday fold is a really cool 3D model of differentially-weathered calc-silicate rocks in Scotland that were folded during the Caledonian Orogeny.
26 January 2018
Friday fold: eastern Andes
This image graces the cover of the new report, Challenges and opportunities for research in tectonics: Understanding deformation and the processes that link Earth systems, from geologic time to human time. A community vision document submitted to the U.S. National Science Foundation: Make it bigger by clicking it The photo is of a landscape in the Eastern Cordillera of the Andes, southern Peru, showing folded Permian carbonates cut by a …
23 January 2018
A kid and his slicks
On a family hike, Callan’s son finds some interesting smooth lines on a rock. What are they? What do they tell us? Tune in for a brief history of Appalachian geology.
10 January 2018
SGTF field trip
A virtual field trip to the Phoenix Mountains and South Mountains of Arizona, along with participants in the 2018 Structural Geology and Tectonics Forum.
30 December 2017
Normal faulting in the San Felipe Volcanic Field, New Mexico
A glance out the airplane window over New Mexico triggers a bit of web research and a new view of tectonic extension via Google Earth and geologic maps.
8 December 2017
Friday fold: Alpine cross sections by Albert Heim
The Friday fold is a figure from a 1922 book about the geology of the Alps by Swiss structural geology genius and artistic master Albert Heim. Marvel at his gorgeous depiction of the internal and long-since-eroded structure of these mighty mountains.
5 December 2017
The quarry in Contessa Gorge
Central Apennine stratigraphy and structure is on display in the wall of a quarry in Contessa Gorge, Italy. Have a look a nice normal fault and a submarine mass transport deposit.
27 October 2017
Friday fold: Quantankerous veins
What does it mean for a vein to be “quantankerous?” Well, to start with, it’s quartz. Second, it has to be disagreeable or cantankerous. This vein, seen in meta-arkose of the Catoctin Formation near the summit of the Blue Ridge at Rockfish Gap (not Afton Mountain), is such a quantankerous individual: You’ll notice its “S” shape, which might imply top-to-the-left kinematics. But just down the outcrop is this set of …
29 September 2017
Friday folds: soft sediment deformation in thin sections of MTD sandstone
The Friday folds are small soft-sediment deformational features within a dismembered, folded sandstone (a “ploudin”) from a mass transport deposit from the latest Devonian of West Virginia.
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.