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You are browsing the archive for September 2014 - Mountain Beltway.

29 September 2014

Charnockite at Swift Run Gap

Over the weekend, I ran a 1-credit field course for NOVA, on the geology of Shenandoah National Park. I was about eight minutes early getting to the meet-up location, so that allowed me to check out a promising new outcrop of rock along the road (route 33, ~100 m west of Swift Run Gap). Here are two photos of it: charnockite (pyroxene-bearing granitoid or meta-granitoid), with weak foliation: This is …

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26 September 2014

Friday fold: passively folded marble

It’s Friday! Here’s Baxter, last Friday, in Athens, Greece. He’s checking out some folds in the marble that’s everywhere in that city: This is a lovely example of passive folding, where all the rock layers being folded have about the same viscosity (low viscosity contrast between layers). No buckling, as a result… Enjoy the weekend, hopefully passively!

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23 September 2014

Santorini: where the Hellenic arc meets the Cyclades

The geologic story of Santorini begins, with some tectonic perspective on the two major aspects of subduction recorded in the island’s rocks.

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22 September 2014

Sea arch in pyroclastic deposits, Santorini, Greece

A series of blog posts on the geology of Santorini and Athens, Greece begins with a look at a sea arch on the south shore of Thera.

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19 September 2014

Friday fold: Miette Group anticline in Banff National Park, Alberta

Here’s an outcrop of Miette Group slate, seen at the intersection of the Icefields Parkway with the Trans-Canada Highway, just north of Lake Louise, Alberta: There’s a lovely anticline just to the right of Zack, who obligingly provided a sense of scale. Also note how cleavage which is subparallel to bedding on the far left side of the outcrop, becomes perpendicular to bedding along the crest of the anticline… Happy …

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12 September 2014

Friday fold: Quartz vein in Catoctin Formation, Point of Rocks, Maryland

I took this image in 2005, when I was working up a geologic history of the C&O Canal National Historical Park. It’s a vein of quartz, gracefully folded within the Catoctin Formation. The exposure is along the railroad tracks at Point of Rocks, Maryland, easternmost extent of the Blue Ridge province on the north shore of the Potomac River. The Culpeper Basin begins about 100 meters to the east of …

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8 September 2014

Grizzly pig

Archaeotherium skull, on display at the Royal Tyrrell Museum in Drumheller, Alberta: I love these beasts since I first encountered mention of them at Badlands National Park, and reading them dubbed “grizzly pigs” in the excellent book Cruising the Fossil Freeway really stuck with me – these were pigs filling a predatory ecological niche we don’t really see them in today.

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5 September 2014

Friday fold: Kink banding in the Arran Islands

This one is in my folder of ‘structure’ images on my computer, but it’s not one of mine. I’m not sure where it came from. A TinEye search turns up nothing. Perhaps one of¬† you can tell me? Lovely subparallel kink bands… such gorgeous structure. Happy Friday!

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3 September 2014

Rugose corals in the Clearville member of the Mahantango Formation

Here are some rugose coral fossils (along with some cross-sectioned articulate brachiopod shells) to be seen in the Clearville member (~80 feet thick) of the Mahantango Formation, exposed on the north side of route 55, just west of the West Virginia / Virginia border. These fossils are cool in their own right (what fossils aren’t?) but here they’re serving another purpose – they’re letting us know where we are in …

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1 September 2014

Field work on the Grinnell Formation at Red Rock Canyon, Waterton Lakes National Park, Alberta

Callan’s Rockies field course students document faulting and jointing in Red Rock Canyon, Waterton Lakes National Park, Alberta.

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