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You are browsing the archive for November 2017 - Mountain Beltway.

28 November 2017

A new approach for teaching the geologic history of Virginia

I believe in tinkering with my teaching, and reflecting on the new approaches to see if I think they’re worth keeping or not. One of the topics I teach is the geologic history of Virginia. I do this because it’s essential knowledge to put the students’ upcoming field trip in context, but it’s also a nice example of how geologic techniques can be applied to understand the history of a …

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27 November 2017

Visiting the K/Pg boundary at Bottaccione Gorge, near Gubbio, Italy

A trip to one of the most famous outcrops in the world, a place with a stratum that marked a profound shift in the state of the planet, and a profound shift in geologic thinking. Plus, for the author, it’s a romantic journey back in time.

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Pre-post contest: What is this book?

Which of you can you tell me what this green book is all about (three volumes)? I’ll follow up in 1 hour with a post about the place where I took this photo.

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24 November 2017

Friday fold: Idaho Springs Fm. amphibolite

Here’s a guest Friday fold from reader Carl Brink: Carl tells me that this is: Precambrian Amphibolite schist float boulder from the Idaho Springs Formation in Rist Canyon west of Fort Collins, Colorado.Ā  Knife is 2.25 inches long. Thanks for sharing, Carl!

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10 November 2017

Friday fold: soft sediment deformation in California’s Castaic Formation

The guest Friday fold comes to us from the Miocene of California, deposited in a releasing bend basin along the San Andreas Fault.

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3 November 2017

Friday fold: More kinks from Glacier National Park

This Friday, let’s return to Glacier National Park. Here are some folds in Helena Formation limestone: Can’t see them? Fair enough – the point of maximum inflection appears to be hidden behind a snow-filled gully: But in addition to that big fold, there are several kink bands in there, too. Let’s zoom in: Here they are: Zooming in further, on the right-most of these kink bands: …And here, with the …

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2 November 2017

Weathering in komatiite

This morning on Twitter I was reminded of komatiites, those “extinct” ultramafic lavas that were relatively common eruptions during the Archean. I’ve actually got a good number of komatiite photos to share from my time last year in South Africa’s Barberton Greenstone Belt. But since time is short this morning, I’ll start with a short photo set of three images, all showing different aspects of how these ultramafic rocks weather …

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