Have a gander at this: Given that this is a Friday on Mountain Beltway, you might expect to see a fold here, and indeed, there’s something wavy and high-contrast running through the center of this sample. But that’s no fold. It’s a fossil plant! A “reed” of some kind, I guess. You can also see … Read more
As with last week, the Friday fold comes from my Field Studies in Geology class to Sideling Hill and the Paw Paw Tunnel. This is a view of the downstream (north) entrance to the Tunnel, with students highlighting the trace of bedding in the turbidites of the Brallier Formation: Can’t make it all out? Let’s … Read more
Here’s what the Sideling Hill road cut looked like last month: It’s a terrific example of a syncline. Usually I show folds in profile view, but here, the view is essentially perpendicular (not parallel) to the axis of the fold: Sideling Hill’s rocks are early Mississippian in age, made of debris shed off the late … Read more
My student James O’Brien took this image of a kink band along the Billy Goat Trail, downstream of Great Falls in Maryland’s metamorphic Piedmont province. A lovely little structure, don’t you think? Thanks, James! Happy Friday, all.
We have a guest Friday fold today, from reader Ben Mackay-Scollay of the Monash University School of Geosciences in Melbourne: Ben writes: Hey there Professor Bentley, been a fan of your blog for a while and I thought you might be able to use this for your Friday Fold series. It’s an upright fold at … Read more
It’s Friday… that means it’s time for a fold. Let’s try this outcrop at “Confusion Hill” in the Franklin Mountains of West Texas: See it? Let’s zoom in… From the shadows to the left of the hammer, trace out the dark green layer… it may make you think of a box fold: …but it’s not. … Read more
I know nothing about this sample, other than the fact that it was a thrown-away sample found in the rock pile next to the old geology building at the University of Texas at El Paso. Happy Friday!
Happy Friday! Here’s a beautiful folded obsidian sample, replete with conchoidal fractures, on display outside the geology department at Arizona State University in Tempe, where I was last week:
For the Friday fold, let’s journey back to the Silurian, as exposed in the limestones of that age that were deformed during Alleghanian mountain-building (Pennsylvanian and Permian), and exposed along Corridor H in eastern West Virginia. Some buckling (cuspate-lobate form) seen in that one… A little pop-up with hinge collapse: And, finally, as a digestif, … Read more
Howard Allen, a blog reader from Canada, digitized a bunch of folds for us from his old Kodachrome slides. You’ll be seeing selections from these images over the weeks to come. Get psyched! There are some great folds in this batch. Here’s the first: Howard’s description: 3D folded marble, Shuswap Metamorphic Complex, north of Sicamous, … Read more
Scott Johnson contributed this special “Valentine’s Day” edition of the Friday fold: a lovely primary igneous structure that evokes a heart: That’s a close-up view (lens cap for scale) that Scott took when he GigaPanned this feature: link … the big obsidian flow at Newberry Crater in Oregon. That’s a really dry lava flow that … Read more
I ran out of folds last December, I asked for help on Twitter. Laura Hamilton was among the first to respond, with a link to this image: @callanbentley Hartland Quay, Devon UK. Huuuuge chevron folds! pic.twitter.com/7bhRfLib9Y — lau.rah (@hammijam) December 23, 2013 Thanks, Laura, for another great image!
Todd Redding is our genorous sponsor for this week’s Friday fold. Todd reports that this boulder is derived from the Okanagan Metamorphic Complex near Penticton, British Columbia, Canada. He gives its lat/long as 49°28’14.10″N, 119°30’23.14″W. Did you spot the small fault in there, too? Thanks for sharing, Todd!
Reader Eric Fulmer contributed this week’s Friday fold. It’s a beauty! Eric writes that this outcrop is from “the Belgian Ardennes near Durbuy. There’s a well-exposed anticline along the Ourthe River. The stone is late-Devonian limestone typical of the immediate area that was later deformed regionally due to the Variscan orogeny. The Ardennes are classic … Read more
Another guest Friday fold – again, from the structural geologist Christie Rowe at McGill University in Montreal: Christie describes this as: growth faulting in beautiful fluvial sediments… Accordingly, I have squinted and annotated it a bit: Happy Friday!
Another guest submission for the Friday fold. This one comes to us from Christie Rowe, and it shows a tiny kink fold in the Bitter Ridge formation (playa limestones):
My former student Aaron Barth sent me a few photos of disharmonic folding in metamorphic rocks in Ireland for a guest Friday fold…. Awesome! Thanks Aaron!
I ran out of folds last week, so earlier this week, I asked for help on Twitter. Laura Hamilton responded with a link to this image: @callanbentley El Gordo, S Spain. Huge turbidite block! Folded over as it moved over the seafloor 🙂 pic.twitter.com/L4INxmtLTq — lau.rah (@hammijam) December 23, 2013 Sweet. And you can’t complain … Read more
The laccolith of Cristo Rey, at the Chihuahua / Texas / New Mexico triple point, is host to some cool geology. It’s cored by the Campus Andesite (47 Ma, Eocene) but surrounding the intrusion are a slew of sedimentary rocks, include the Turitella-bearing limestones of the Buda Formation and the shales and sandstones of the … Read more
Hiking up to Crypt Lake in Waterton Lakes National Park, Alberta, Canada, you can see some sweet stromatolites, and folds, too. But it’s not only that – you can also find some decent kink bands in those strata, too! These kink bands will serve as our Friday fold, on this Crypt-Lake-o-centric week. Here’s a second, … Read more