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20 August 2022
Two erratics from coastal Maine
Happy Saturday! Here are two erratics (glacially transported boulders) that I saw last week in coastal Maine. This one shows prominent subparallel striations: And this one, in the town of Penobscot, next to the greasy spoon called Bagaduce Lunch, shows aligned feldspars that suggest magmatic flow: Nothing like a good erratic to get the weekend started off right!
17 May 2019
Friday fold: Found folds
This week, for Friday folds, I offer up some random folds that have passed my perceptual transom this week. First up: In the new Netflix series Our Planet, in episode 7 (Fresh Water), an anticline/syncline pair makes a brief appearance as David Attenborough discusses glaciers as a reservoir for fresh water. Here is a screenshot: I’m not sure where this is in the world: Greenland? Antarctica? Let me know in …
1 March 2019
Friday fold: Gold Harbour, South Georgia
Near Antarctica, South Georgia Island is a good place to find glaciers and penguins. And, as it turns out: massive recumbent folds! Let’s take a look.
29 January 2019
The Parallel Roads of Glen Roy
What can we learn from Scotland’s Parallel Roads of Glen Roy?
20 July 2018
Friday fold: Alpine peak containing a high elevation recumbent fold
Via Twitter, a Friday fold from Maddy Rushing: #FridayFold, @callanbentley? pic.twitter.com/eaKIuuvFgB — Maddy Rushing (@komaddyite) May 25, 2018 This is in the Alps of Switzerland; I don’t know more about it than that. If you recognize the site or the geology, educate us in the comments!
8 February 2018
A spectacular display of Earth science in the Alabama Hills
A detailed examination of an elegant photo of the eastern front of California’s Sierra Nevada, from the perspective of the Alabama Hills. How many different geologic phenomena can be packed into a single image? Let’s find out!
1 February 2017
An oddball at Eshaness
In eastern Shetland, the sea chews away at the innards of a Devonian stratovolcano. But there’s an odd visitor there too – and we’re not talking about the blogger.
1 June 2016
Varves along Hawk Creek, Washington
Heading into the Columbia River Plateau, Callan and his colleague Bill Richards make a detour in search of some varves from Glacial Lake Columbia. They find them, a credit to the authors of “Washington Rocks!” – the new book from Mountain Press.
26 May 2016
Glaciotectonic thrust at Waubonsee Community College
Glaciers can cause thrust faults! Explore an example from a trench south of Chicago.
8 December 2015
Considering the Spechty Kopf diamictite
I have known for a long time about a diamictite in the latest Devonian part of the Appalachian stratigraphic sequence, since it is exposed in the lowermost part of the section (western end of the outcrop) at Sideling Hill, Maryland. When I led field trips there, I talked students through the multiple possible origins for diamictites (sedimentary rocks that are poorly sorted, with significantly “outsized” clasts “floating” in a finer-grained …
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.