canada

What those geologists were looking at

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Yesterday, I showed you a scene of geologists (including me) clustered around some (presumably interesting) outcrop. I asked what you thought we might be looking at. Howard Allen, a denizen of this part of the globe, immediately identified the scene as that of the downstream end of the Athabasca Glacier. Several people guessed that we … Read more

Cottonwood trees being consumed by caterpillars

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In Waterton Lakes National Park, Alberta, my students and I camped under the shade of cottonwood trees… But some of the cottonwoods’ branches were looking a little thin… Caterpillars were munching on their leaves. And some trees had been completely denuded by the voracious little larvae: All three photos are taken on roughly the same … Read more

Friday fold: Spray Mountain Group siltstone

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Today, we return to Banff National Park, to the outcrops next to the parking area for Bow River Falls… Zoomed-in closer to the thinner layers at left: These strata (shale and siltstone) were laid down in the quiet aftermath of the Permo-Triassic extinction, as terranes colliding with the edge of North America (far to the … Read more

Tool casts from the Sulphur Mountain Formation of the Spray River Group, Banff

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Yesterday I showed you salt casts; today I’ll share a different kind of cast: the infillings of small scorings in the sediment made by tumbling pebbles or sticks or other “tools,”tumbling down a current. These small gouges were later infilled from above by a younger deposit of sediment (frequently coarser in grain size). You’re looking … Read more