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19 November 2015
What geological stories can be read from the stone on the front of a building? Walking past some facing stone in Baltimore, Callan discovers a wealth of little clues.
18 November 2015
You could use a macro GigaPan of some pretty sand, I think. Link That’s sand from near Acadia National Park, in Maine. Exploring it, you can find both small chunks of Acadian granite, and green rods that are sea urchin spines. It’s fun – check it out.
30 April 2015
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?
24 March 2015
A report from the field: new outcrops of Ordovician-aged turbidites featuring geopetal indicators, fossil content, and a structural overprint imparted during Pangaea’s assembly.
22 November 2014
Long week, no blog. But, hey – it’s Saturday, and I have a couple of hours of breathing room – so here are some stylolites in a crinoidal grainstrone in the New Creek member of the Helderberg Formation, exposed on Corridor H in West Virginia. Stylolites are pressure solution features, which overall form perpendicular to the maximum squeezing direction (maximum principal stress direction, σ1), and have little wiggle peaks that …
26 February 2014
More images for you today from my field trip a few weeks ago to West Virginia’s bizarro highway Corridor H, a quiet place built for roaring traffic. Its multistory roadcuts are fresh and profound; they offer the most incredible views into the mid-to-late-Paleozoic surface of Earth… and the creatures that lived there. In the Devonian period, the Helderberg Group of limestones was deposited. It’s full of interesting fossils, the remains …
19 February 2010
Today, you get a photo of a fossilized crinoid stem, from the Mississippian-aged Lodgepole Limestone of the Bridger Range, north of Bozeman, Montana. A pencil is provided for scale: Zoomed-in a bit, and cropped. The segments (“columnals”) show up nicely: Crinoids are echinoderms, the invertebrate phylum which includes sea urchins and sea stars. However, at first glance you might think they were plants, as they are sessile (mainly sessile, anyhow) …