Some time ago, I featured as Friday fold the extraordinarily complex duplex structure to be seen in the Cretaceous “gastropod limestone” member of the Kootenai Formation at Sandy Hollow, Montana. Today, let’s take a deeper look through a couple of hand-shot GigaPan images: Here’s the bigger of the two: [gigapan id=”176119″] link Here’s one with … Read more
My favorite place to have lunch in Montana is at the Grinnell Glacier cirque in Glacier National Park. This is the dining room table: You’re looking at a bedding-plane-parallel exposure of Mesoproterozoic stromatolites here. Every few years, I’m lucky enough to hike up there with motivated students and share food atop this unparalleled view into … Read more
After reading the post last weekend about the discordant offshoot of the Purcell Sill, Rich Gashnig (post-doc at Georgia Tech) sent me a few photos he shot at Piegan Pass (at the head of a side-canyon adjacent to the one containing Grinnell Glacier). They show the Purcell Sill leaving one stratigraphic horizon and jumping to … Read more
Another gem from the Grinnell Glacier cirque: Zooming in on the contact, showing the concentrically-zoned ooids: Near the tip of the flame structure (?), I noted alignment of longer platy / flaky components within the oolitic layer: This looks like a loading structure – soft sediment deformation due to a density inversion – perhaps when … Read more
Howard Allen is the Friday folder who keeps on giving… Here’s his latest: Multiple folds at top of ridge, Opal Range, Alberta. Photographed from Kananaskis Highway 40, looking SE. Beds are Carboniferous carbonates, probably Mount Head and/or Etherington formations. There are lots of great folds to be seen along that road. The Kananaskis Trail is … Read more
Another Friday, another Friday fold from Howard Allen: Folds in near-vertical beds, north side of Grizzly Creek, Opal Range, Alberta. Beds are Carboniferous carbonates, Mount Head and Etherington formations. Enjoy your day!
Kate Littler sent in this Friday fold, via Twitter: lovely parasitic folds in the Carb limestone, West Angle Bay south Wales. Awesome. Looks like a great place. Thanks, Kate! Happy Friday!
Looking at Ordovician carbonates in Germany Valley, West Virginia, a few weeks ago on Rick Diecchio’s GMU sedimentology and stratigraphy course field trip: Lots and lots of brachiopods… Crinoid columnals mized with brachiopods: A set of coarsely-infilled trace fossils: Crinoid stem: Nice strophomenid brachiopod: Bryozoan? Receptaculid?
Here’s another sight at the Eocene dikes site in Bluegrass Valley, Virginia, mentioned yesterday: That’s a gorgeous fault breccia, emplaced parallel to bedding, and parallel to the felsic dike (which can be found a few feet to the west / right of these photos): It was very poorly lithified, shockingly crumbly to the touch, considering … Read more
A virtual field trip to a quarry in far western Virginia, showing anomalous igneous intrusions (a dike and a sill) of Eocene age cross-cutting early Paleozoic carbonates.