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21 January 2023

Plate Tectonics: a very short introduction, by Peter Molnar

This slim volume (130 pages of ~10 point type) is the 425th in Oxford University Press’s vast series of dense little books about various subjects. Browsing the geology shelves at my college’s library this week, I saw it and thought I might as well check it out. I’ve shifted through the years in what I put weight on when teaching plate tectonics, and I always appreciate reading/hearing/seeing what different professionals …


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13 December 2019

Friday fold: blueschist & eclogite at Jenner, California

A pre-Fall Meeting field trip to the coast of northern California yields rare sights of garnet-bearing blueschist, plus eclogite, some pillow basalts, birds, waves, wind, and a lot of rain.


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8 September 2017

Big earthquake in southwestern Mexico, M8.1

The M8.1 southwestern Mexico earthquake is discussed and placed in context.


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21 February 2017

Q&A, episode 3

A reader asks about the use of zircons in isotopic dating, and the argument for submerged continental crust beneath Mauritius.


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20 February 2017

Making “Kate Tectonics”

I recently discovered a terrific series of videos on YouTube called “Kate Tectonics.” Watch episode 2, “The History of Geology,” here, to get a taste of the series’ excellent production values and its hip, humorous style: [youtube=””]   I asked one of the creators, namesake Katelyn Salem, to share a bit of information about the series: Who’s involved in the series? The credits seem lengthy! Can you give a bit …


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25 January 2017

Y-shaped joints on a basalt flow, Lake Mývatn, Iceland

A basalt flow in Iceland shows both enticing pahoehoe and fractures with a Y-shaped intersection pattern. Comparisons to bread loaves and east Africa suggest a reason why.


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15 October 2014

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

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 conformable stratigraphy? Was it a fault? Here’s a closer look at the contact: In places, …


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9 October 2014

In search of Santorini’s blueschist, part 1: into the Valley of the Shadow of Ash

While in Santorini, Greece, your humble geoblogger braves a warm afternoon to search the hillsides for evidence of subduction.


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6 June 2012

Virginia geology on video: the Alleghanian Orogeny

Here’s another video, wherein I’ve made some improvements from the last one (reserved the lower right corner for the webcam “talking head” video inset, and adjusted the microphone for fewer audio blowouts). It’s still not perfect – there’s a disconnect between the audio and the webcam video that becomes more and more pronounced throughout the course of the video, but it’s a step in the right direction. The Alleghanian Orogeny: …


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30 November 2011

Continental Drift vs. continental drift

I got this e-mail this morning from a geology colleague. I’ve despecified it and made it gender-neutral: I have a silly question about word usage and I’d love to hear your opinion. Today I overhead [a biologist colleague] talking about continental drift, and I cringed. S/he used it in context with continents moving apart and how that can alter gene populations. I shudder whenever I hear my students use conti …


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