Callan Bentley The first stop on our pre-GSA field trip to the subprovince boundaries of the Superior Craton was a place just north of Virginia, Minnesota, where the Mesabi Iron Ranges are mined (same Proterozoic banded iron formations that were portrayed as the backdrop of the mining activity depicted in the film North Country). The pull-off is … Read more
I’m on the plane home from the annual meeting of the Geological Society of America, held this year in Minneapolis, Minnesota. This annual event features a robust smorgasbord of science, with talks and posters detailing the research efforts of thousands of geoscientists from the US and other countries. It’s an amazing experience on many, many … Read more
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!
Last spring, I made two visits, six days apart, to Veach Gap, a small water gap superimposed on the Massanutten Synclinorium. One was with my Field Studies in Geology one-day field course, and the second was with my Structural Geology students from George Mason University. We go there to see some lovely parasitic anticlines that … Read more
All this talk about footprints and tail traces, and I haven’t even shown you any “for sure” dinosaur fossils. Well, let’s remedy that today. We return now to the scene: exposures of the Jurassic Morrison Formation, on the east side of the Bighorn Basin, just north of Shell, Wyoming. I was wandering around, finding things … Read more
Okay, so I was out photographing ripples and admiring lichens, and then I saw this: That’s a rippled slab of sandstone, but with a linear groove that obliquely cross-cuts the ripple marks. Smaller, parallel grooves lie within the main groove. Here’s another look at that same one, spun around and zoomed-in: It looks as if … Read more
Picking up from Saturday’s post about ripple marks and cross-bedding in Morrison sandstone from north of Shell, Wyoming, let’s scoot away from the purely geological content for a moment, so that we can appreciate some beautiful orange/yellow radial lichens growing on one rippled sandstone slab: You can make that one bigger by clicking on it, … Read more
This past summer, the day after my examination of basement complex along the Colorado/Wyoming border, I drove north to Greybull, and then with Virginia Museum of Natural History paleontologist Butch Dooley to a dinosaur dig site north of Shell, Wyoming. There, in the Bighorn Basin west of the Bighorn Mountains, are dinosaur-bearing exposures of the … Read more
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.)
By local prodigy Hannah Holland, elementary school student: Click through to make it bigger and see some details. Nice work, Hannah! Very impressive, and thanks for sharing!
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.
The geologic timescale: Where did those names come from? Here’s some etymological information I share with my Historical Geology students so that the names become meaningful symbols of ideas, rather than simply of bunch of nonsensical gibberish to memorize… Phanerozoic eon – Greek for “visible life” Cenozoic era – Greek for “new life” Quaternary – … Read more
Along the Beartooth Highway, east of Cooke City, Montana, you will see this striking mountain: Click through to make it really big. That’s Pilot Peak. It’s a horn in Wyoming. My Rockies students get really jazzed when they see it. Glaciers carved away the rest of the mountain, leaving only this pyramidal spire. Awesome.
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
More moki marbles: little concretions in sandstone, kind of like the ones I showed you Tuesday from Illinois. But these ones are from the Navajo Sandstone, a late Triassic or early Jurassic erg deposit from the Colorado Plateau. These photos were taken in Zion National Park, near Springdale, Utah (real close to the cross-beds I … Read more
At the Burgess Shale this summer, it wasn’t all fun and fossils. I also saw a lovely, distinctly feather-shaped plume: This is an example of plumose structure – the subtle branching micro-topography that forms on the surface of a joint as the fracture propagates out from its origin. The more obvious “rib” that is perpendicular … Read more
At the end of the summer, there was a conversation on Twitter about having a meet-up (“rendezvous” sounds more authentic, it was pointed out) for folks involved in geology social media: stuff like geoblogs and Twitter, but pretty much open to whoever’s into meeting up in some interesting place and exploring some geology together. Following … Read more
Giant City State Park is a patch of protected forest south of Carbondale, Illinois, where there are some pretty cool exposures of Pennsylvanian-aged Makanda Sandstone. Here’s a typical look at one: Notice the deep chasm on the right. This leads, maze-like, to other flat-bottomed and vertically-walled canyons: The orthogonal joint sets produces some nice tall, … Read more
Hurricane Irene passed this way two weeks ago, and dumped a lot of rain on the mid-Atlantic region and the northeast. As a result, runoff increased, rivers swelled, and sediment was mobilized. Some of that sediment was suspended and transported downstream. On Tuesday, I got this e-mail from my colleague Ken Rasmussen, who took students … 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