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27 June 2011
Goose Egg / Tensleep contact
West of Shell, Wyoming, on route 14, there is a lovely exposure showing the tilted stratigraphic contact between the lower Tensleep Formation (purple; Pennsylvanian period) underneath Goose Egg Formation (orange/tan; Permian to Triassic in age). The contact dips to the west because it has been deformed during Laramide mountain-building (uplift of the Bighorn block, and downdropping of the Bighorn basin). Here’s a gigapan to show the contact:
25 April 2011
Two joints
Stopped at Sideling Hill, Maryland, a few weeks back with my three Honors students, on our way to Pittsburgh for the northeast/north-central GSA section meeting. Robin took this photo of me with some sandstone beds that reveal two nice examples of joint anatomy, complementary in their structure: First focus in on the area right of where my finger is pointing. It shows well-expressed plumose structure, little lines that point in …
18 February 2011
Friday fold: Jefferson River Canyon
Here’s your Friday fold, straight from the canyon of the Jefferson River, near Cardwell, Montana. Perspective is to the south. East is on the left; west is on the right. Bigger version This is right next to the outcrops of LaHood Conglomerate that I mentioned earlier this week. My Rockies course co-instructor Pete Berquist and I bring the students here for several reasons, including the conglomerate, nearby Lewis & Clark …
21 September 2010
EARTH: the biography, by the BBC
Last week, I watched the BBC/National Geographic series “EARTH: The Biography,” hosted by Iain Stewart. Stewart is a charismatic host, with a thick Scottish accent that cannot disguise his enthusiasm for geology. The five episodes focus on: volcanoes, ice, oceans, atmosphere, and “rare planet.” Overall, I thought the series did an good job covering some of the greatest stories in geology with an emphasis on presenting the latest ideas. Snowball …
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.