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8 March 2019
Friday fold: Dent de Morcles
The Friday fold is a recumbent anticline/syncline pair, deforming the K/Pg boundary in the Swiss Alps, as photographed from the air by Bernhard Edmaier.
27 November 2017
Visiting the K/Pg boundary at Bottaccione Gorge, near Gubbio, Italy
A trip to one of the most famous outcrops in the world, a place with a stratum that marked a profound shift in the state of the planet, and a profound shift in geologic thinking. Plus, for the author, it’s a romantic journey back in time.
11 October 2016
A virtual field trip to Portrush, Northern Ireland
One of my favorite places in Northern Ireland is the east side of the peninsula that hosts the tourist town of Portrush. There, two early schools of geological thought engaged in a battle. The opposing sides were: the Neptunists, who thought all stratified rocks, and in particular basalt, must form from precipitation from the sea, and the Plutonists, who thought some rocks, including basalt, formed through intrusion of molten rock …
13 June 2014
Friday fold: tortured turbidites at Devil’s Slide
Marek Cichanski (of De Anza College near the south end of San Francisco Bay) contributed this week’s Friday fold: Marek says: The locality is a place near San Francisco called Devils Slide. It is a piece of the coastal highway built along a steep mountainside above the ocean. This unstable stretch of road was recently (finally!) replaced by some tunnels. And, amazingly, the old roadbed finally got converted to a …
12 December 2013
Some folds along the Crypt Lake trail
Hiking up to Crypt Lake in Waterton Lakes National Park, Alberta, Canada, you can see some sweet stromatolites, We’ve already taken a look at the falls, but today, let’s zoom into the folds exposed in that shadowy cliff near the center… These limestone layers are Mesoproterozoic in age – they’re part of the Purcell (Belt) Supergroup. The folding likely dates to the late Cretaceous into early Paleogene “Laramide” Orogeny (as …
28 February 2013
Unconformity seen in the field yesterday
Callan and two colleagues find a “textbook” unconformity on a field trip in Virginia’s westernmost Blue Ridge.
4 May 2012
Friday fold: ball & pillow in volcanic ash
Another guest Friday fold – this one supplied by Ander Sundell of the College of Western Idaho, and his student Katie Ursenbach, who took the shot and gave permission for me to re-post it here. You’re looking at cuspate-lobate folds due to primary sedimentary settling. the Snake River Canyon in southwestern Idaho. A pile of volcanic ash erupted into water in the Paleogene, and soon after covered by a series …
14 September 2011
Is “Tertiary” archaic?
Jack and Drumlin are visiting for the day from their usual home.
25 January 2011
Uncommon Carriers, by John McPhee
Over the weekend, hideously cold temperatures kept me indoors. I baked a cake, I went to see the new movie “True Grit” (excellent), and I read the 2006 compilation of John McPhee’s writing on transportation, Uncommon Carriers. Like most everybody I know, I came to McPhee based on his geology writings — the quartet of books that were collectively republished en masse in 1998 as Annals of the Former World, …
Uncommon Carriers, by John McPhee
Over the weekend, hideously cold temperatures kept me indoors. I baked a cake, I went to see the new movie “True Grit” (excellent), and I read the 2006 compilation of John McPhee’s writing on transportation, Uncommon Carriers. Like most everybody I know, I came to McPhee based on his geology writings — the quartet of books that were collectively republished en masse in 1998 as Annals of the Former World, …
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.