Callan Bentley

Yamnuska

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Driving west from Calgary, your first evidence of entering the Canadian Rockies’ Front Ranges is the startling sheer cliff of Yamnuska, north of the Trans-Canada Highway: Yamnuska’s shape is a function of differential weathering of the two rock units that make up the mountain: Cambrian Eldon Formation limestone, and Cretaceous shales of the Brazeau Formation. … Read more

Bedding / cleavage relations in the Stephen Formation, Yoho NP

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Good afternoon! Here are a few photos, both plain and annotated, showing the relationship between primary sedimentary bedding and tectonic cleavage in the “tectonised Stephen” Formation atop the Cathedral Escarpment (in Yoho National Park), just northeast of the Walcott Quarry where the (thicker, basinward) Stephen Formation hosts the Burgess Shale. Weathering exploits both these planes … Read more

GSA and the Biggs Award

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The recently-concluded Geological Society of America meeting in Vancouver, British Columbia, was one of my best meetings ever. I gave two talks and a digital poster, supervised three student digital posters and one student group regular poster, attended and contributed to meetings on a variety of subjects, met new colleagues, reunited with old friends, and … Read more

Friday fold: Three more from the Chancellor Slate

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Remember our examination of buckle folding versus passive folding in the Chancellor Slate (cleaved limy mudrock) of eastern British Columbia? Well, here’s another example: There’s so much awesomeness going on in that image, it’s hard to know where to start. The prominent black thin layers are buckled in a very boxy, asymmetric way. In places, … Read more

Boudinage in Santorini schist

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While on my blueschist quest, I noticed this boudin train exposed in the trail. I’m not sure what exactly is being boudinaged here – only that it is lighter in color than the schist that surrounds it, as well as finer grained and less foliated (more massive). A tabular mass of fault gouge perhaps?

In search of Santorini’s blueschist, part 2: finding fault

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As mentioned last week, I took a solo field trip north of Perissa, Santorini, Greece, in search of subducted rocks. The contact between the two main rock types (marble and schist) was prominent and visible from a great distance (see photos in previous post), but what was the nature of this contact? Did it represent … Read more

Friday fold: passively folded marble

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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, … Read more

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

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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 … Read more

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

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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 … Read more

Grizzly pig

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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 … Read more