While out in the field with Butch Dooley last week, making major discoveries like I do, I was very impressed with the landscape-scale west Bighorn monocline, which takes formerly horizontal Madison limestone and skews it to a westward dip where the mountains end and the intermontane basin begins. It’s totally sweet. Check it out in photo form and gigapan, too.
A boulder outside the door of the Geological Museum in Laramie, Wyoming. Purty, parasitic, passive folds… Happy Friday. My field course starts tomorrow here in Bozeman. I’ll soon have a lot less time for blogging. Brace yourself.
This Friday, I give you a fold from the shores of the Rockfish River, south of Charlottesville, in Virginia’s Blue Ridge basement complex, and just down the road from the Lawhorne Mill High Strain Zone. The fold distorts (and improves) a felsic dike cutting the darker granite of the basement. You can make this (stitched … Read more
The Friday fold features fine faults from a forgotten font, and a failed foto-finding forage.
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Today’s Friday fold takes me back 25 years, to when I visited the Outdoor Lab with my science class in Arlington County Public Schools. I revisited this exemplary outdoor education facility on Tuesday, at the invitation of its director, Neil Heinekamp. Neil wanted a geology “expert” to take a look at their rocks, and I … Read more
Today’s Friday fold comes to us from Alistair Knock on Flickr*, via Dave Schumaker’s Geology News Blog, where there is a daily Flickr feed of photos tagged with the word “geology”: Bigger version here. The fold in question, an overturned synform, is at a place called “Butt of Lewis” (the northernmost point on the island … Read more
Last week, the Friday fold featured a kinked phyllite of unknown provenance that is currently resident in David King Hall 2074 on the campus of George Mason University. However, on Tuesday of last week, I found another kinked phyllite, this one out in the real world, at Thoroughfare Gap, in the Harpers Formation of the … Read more
Yesterday afternoon, I spent some time in the field with a colleague, a student, and a gigapan. I took four gigapan images, which are of varying quality due to the partly cloudy day, but still you ought to find them interesting to explore. You can see any of them full-screen by clicking on the word … Read more
Kink bands in phyllite. Another sample from the GMU teaching collection. Ruler in the background shows blurry mm-scale demarcations. Happy Friday — enjoy your weekend!
This is a sample from the teaching collection at George Mason University: The swirly folds exhibited by this quartz vein reminds me of von Karman vortices. Happy Friday! For me, it’s the last day of classes of the spring semester at NOVA, though GMU is still in session for a couple more weeks. I’m grateful … Read more
The Friday fold is a contorted chert sample from Turkey.
The Friday fold is glimpsed from Google Earth. Atop a valley glacier in south-central Alaska’s Kenai mountain range, a fold of “transverse moraine” displays parasitic folds.
Spotted this one a week ago today, when I was out exploring north of the Rocky Islands with my GMU Structural Geology students…
Cretaceous calcarenite layers, folded along the coast of Spain (?). From the repository of geological images hosted by the European Geological Union, Imaggeo. I was reminded of Imaggeo earlier this week, and it’s a great place to go browse around for cool photos of geological things. It could use a better search interface, but oh … Read more
We now return to Mount Washington, New Hampshire, where our intrepid heroes summit the mountain in a mere three hours (from Pinkham Notch via the Lion Head): To refresh your memory of the story so far, we had seen metamorphosed turbidites, like this one (new image): …and checked out some gorgeous metamorphic porphyroblasts of “pseudoandalusite,” … Read more
At last weekend’s northeastern / north-central GSA meeting in Pittsburgh, David Saja of the Cleveland Museum of Natural History presented a talk entitled, “Geometric Analysis of Folded Greywacke Layers from Pacheco Pass, California.” [Abstract link] In addition to the standard PowerPoint presentation that 99% of GSA speakers use, David also brought in some hand-samples (what … Read more
More from Mount Washington, New Hampshire: some folds in the Madison Member of the Littleton Formation (schist) along the auto road near Cragway Springs (just past 5 miles up; see map below): IMAGE SOURCE The folds are asymmetrical, with long west-dipping limbs, and shorter east-dipping limbs. Happy Friday!
That title sounds kinky, right? Well, calm down. I’m behind the curve on the latest Accretionary Wedge (as I was for the one before that), but here’s a quick image to join the parade of geologic photos that Ann is hosting. While it’s not my favorite, it’s definitely a favorite, more by virtue of the … Read more
Another fold seen in the Catoctin Formation, where last week we encountered a very different style of folding — chevrons overprinting Catoctin foliation. Here, we instead have a light colored vein that appears to have been buckled into a semi-ptygmatic form. The trace of the foliation in the Catoctin is discernible, too. Enjoy your Friday!