You are browsing the archive for Friday Fold Archives - Page 6 of 46 - Mountain Beltway.
14 February 2020
Friday fold: Miocene slump in Anza-Borrego
Today’s Friday Fold comes from Edith Carolina Rojas, the dynamic geology professor at The College of The Desert in Palm Desert, California. She’s an awesome person, and also the sense of scale in this amazing image: Edith shares that this gorgeous structure is an anticline is located in Split Mountain Gorge in Fish Creek Canyon. It’s a gigantic gravity-slide fold due to soft sediment deformation in the Latrania Formation. Wow …
7 February 2020
Friday fold: Kings Canyon
The Friday fold shows disharmonic crumpling in marbles of the Boyden Cave Root Pendant in California’s Sierra Nevada. The GigaPan image displayed is part of the digital legacy of Ron Schott, who passed away a year and a half ago.
31 January 2020
Friday fold: tension gashes near Sunflower, Arizona
Reader John Christian shared these folds with me via email last week. They are quartz veins in slightly metamorphosed Precambrian igneous rocks found near Sunflower, AZ in the Mazatzal Mountains. The second photo is a close-up shot of the curviest, cleanest batch of folds from the first shot. These are beautiful examples of folds in similarly oriented quartz veins; we call them “en echelon” for the way you have a …
24 January 2020
Friday fold: Pelham Parkway
A roadside boulder in the Bronx shows folded gneissic banding. It’s another guest-submitted Friday fold!
6 December 2019
Friday fold: a secret Santa rock exchange gift!
I participated this year in the Secret Santa Rock Exchange, wherein I shipped out a mystery rock to a random person, and got back a mystery rock from another random person. What fun! My mystery rock has folds in it! It’s from Matt Bruseke at Kansas State University. Check it out: Matt writes that this is a piece of the Silver City rhyolite, from the Owyhee Mountains, Idaho. The sample …
22 November 2019
Friday fold: Noonday Dolomite in Mosaic Canyon
Because I’m putting together a field course for spring break 2020 to Death Valley California, I was looking through old Death Valley photos this week, from the last time I went to that special place. It was seven years ago! How time flies… This one is in Mosaic Canyon, and was taken by my student Marcelo Arispe, a talented photographer as well as a talented geologist: By the standards of …
15 November 2019
Friday fold: two samples from Tennessee Tech
I spent some time in east central Tennessee last week, visiting the Earth Sciences department at Tennesee Technical University in their lovely newly-remodeled home on the main campus quad. In a hallway display case, they had many beautiful specimens on display to educate and inspire. Here are two lovely examples of folding. Terrific rocks to take us into a terrific weekend. Have a good one!
8 November 2019
Friday fold: Rist Canyon cobble
From a creek bed in northern Colorado, the Friday fold distorts foliation in early Proterozoic quartzofeldspathic gneiss, peppered with small almandine garnets.
1 November 2019
Friday fold: Newfoundland beach cobble
This Friday’s fold is found in a metasedimentary beach cobble I found last summer in southeastern Newfoundland: A lovely little “pocket fold,” it came home with me and is among the handful of “deskcrops” I keep in my home office. Happy Friday and happy November!
25 October 2019
Friday fold: Identity of a BIF
The Friday fold is a slab of banded iron formation now dwelling in the University of Washington’s Department of Earth & Space Sciences. But where did it come from? India? Brazil? Perhaps you can help identify its provenance.
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.