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3 August 2018
Friday fold: a recumbent set of turbidites in the Black Hills
Today we feature a famous recumbent, chevron anticline near Hill City, South Dakota has been featured as a Friday Fold or not, but thought I would give it a go. The rocks are Proterozoic metagreywacke turbidites with 70 complete or partial Bouma sequences. This is believed to be a late (D4) fold in the Black Hills related to upward doming associated with the emplacement of the Harney Peak Granite, which …
4 July 2012
Plane views: Powder River Basin and Black Hills
Happy fourth of July! Here’s two scenes that are emblematic of America, as seen from my airplane window last March flying from Reno to Minneapolis. Here’s the scene in the central Powder River Basin of eastern Wyoming: If you zoom in, you’ll see what caught my eye – regular rectangular excavations into the surface. These are strip mining operations for coal laid down in the Paleogene period of geologic time. …
11 November 2010
Microfaults-a-million
I got to Pittsburgh around 1:30pm yesterday, which meant I had several free hours before the opening reception for new Fine Fellows. I took a bunch of photos of the exhibits there, but my traveling laptop doesn’t have the image processing software that I usually employ to resize these things, so for now I’ll just share this one. It’s a sandstone from South Dakota, age unknown, which shows beautiful parallel …
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.