The “Friday fold” is an isoclinal dextrally-asymmetric granitoid vein exposed north of Fort Frances, Ontario. Taken on October 7, 2011, the photo features a centimeter-demarcated pencil for scale. It shows thickened hinges, boudinage of the lower right long limb, and incipient boudinage of the upper left long limb.
The Friday fold is a guest photo by James Edward Bailey, a 5th grade student from Reston, Virginia. It is the anticline shown is known as “the Devil’s Backbone,” located near Marlinton, West Virginia, right on the boundary between the Valley & Ridge province and the Appalachian Plateaus. It clearly shows differential weathering of weaker layers and tougher layers. …Also some lovely fall colors!
Straight-limbed open synform in an organic-rich formation of limited areal extent, featuring some brittle extensional features at the hinge. Kootenay National Park, British Columbia, summer 2011. (The bridge was broken before we got there.)
Northern Colorado’s route 287 connects Fort Collins, Colorado with Laramie, Wyoming. Along its length, it displays roadcuts into Archean-aged basement complex. Two of these outcrops are featured in this post: one metamorphic (mostly), and a second igneous (mostly), with some intriguing polka-dotted plutons.
Whilst at the JMU Field Camp in Ireland this summer, my former student Alan Pitts (author of Not Necessarily Geology), collected this lovely “pocket fold” near Derryclare Lough and brought it back to the States. A couple of weeks ago, after a graduate school advising session at a pub in Fairfax, Alan gifted me the … Read more
Reader Jacob Langseth sent in this image of a lovely fold that he recently saw in the Blue Ridge province of Georgia. It’s located in an old CCC rock quarry, off of the Pine Log Creek Trail system, in Bartow County. You can click on that first image to make it bigger and see a … Read more
You’re looking here at Mount Kidd, a peak in the Front Ranges of the Canadian Rockies that displays a tight anticline/syncline duo superimposed on the strata of the Rundle Group. Located on the west side of Highway 40, the Kananaskis Trail, south of the trans-Canada Highway, this mountain shows us what happens with Carboniferous-aged carbonates … Read more
The Friday fold is a gorgeously deformed “duplex structure” in Mesozoic limestones of southwestern Montana.
Lee Allison, State Geologist of Arizona and exemplar of public outreach via blogging, sent me an e-mail yesterday regarding that awesome coastal Greenland shot by Alistair Knock that I featured as the Friday fold. Lee, like many of you, found the image entrancing and intriguing, and as he explored the unannotated version, he made some … Read more
The Friday fold is a beautiful straight-limbed antiform from coastal Greenland, courtesy of photographer Alistair Knock. Check it out and see if you can find anything that Callan didn’t annotate.
My man Walcott contributed a lot of images to the USGS stockpile during his travels. Today, I’ll feature one from Bishop, California, from 1894: Got it from here. Rock hammer on the left for scale. The caption reads: Plicated layers of thin bedded chert in limestone etched by erosion, Lower Cambrian (?). Hill two miles … Read more
That’s from the side of route 287, somewhere between Fort Collins, Colorado, and the Wyoming border. Though I took this shot >6 weeks ago on my outward-bound trip, today I find myself back in Fort Collins on the eastward leg of my summer road jaunt. And you know what one does in Fort Collins. Happy … Read more
Callan embarks on an exhausting climb of a major summit in the Wyoming Bighorn mountains, a peak named in tribute of one of his geological heroes. Come join the trek to the top of Darton Peak!
Here’s one of the first things as you drive north from Chief Mountain in Glacier National Park, and cross the border into Alberta: The mountain in the middle is Crandell Mountain, and it looms to the north above the village of Waterton Lakes, but the lovely folds it displays are best viewed from a more … Read more
To follow up on my March post on the French Thrust, here’s a gigapan of the outcrop. Sun River Canyon, Montana, of course: the Sevier fold-and-thrust belt.
Folded quartzofeldspathic vein in amphibolite, Wyoming Terrane basement complex, Montana.
Dave Lageson of Montana State University and I ran into each on our respective field trips sometime last year outside of the Two Medicine Dinosaur Center in Bynum, Montana, and he told me that I had to go check out the Swift Dam area, a little ways northwest of the town of Depuyer. So, a … Read more
That’s my Rockies co-instructor Pete Berquist, in the regulation uniform of an orange down vest, holding a subtly-folded slab of sandstone (it’s a very slight “S”), rescued from amid the shaley wastes of the Blackleaf Formation, the Cretaceous aged sedimentary rocks beneath the Lewis Thrust on the Blackfoot Reservation, just east of Glacier National Park. … Read more
Following up on Friday’s fold, I wanted to share a few other images from our hike last week in Cascade Canyon of Grand Teton National Park. Lots of cool exposures of Archean basement rock there. Folds in gneissic banding: Big, angular mafic blocks in a felsic soup: Swarm of granite dikes on a mountainside: Asymmetric … Read more
Spotted this in Cascade Canyon, in the Tetons of Wyoming, last weekend: Nice asymmetric antiforms and synforms in the gneissic layering of the Archean basement rocks exposed there. Also, we saw a bull moose. More on that later on, when I get more time.