You are browsing the archive for Callan Bentley, Author at Mountain Beltway.

21 January 2024

Swan song

A few reflections on the AGU Blogosphere’s long, strong run, and a vision for Callan’s future online outreach.


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1 January 2024

Yard list 2023

Another year has elapsed at the usual rate, and now it draws to a close. Time for me to tally up the year’s sightings. My goals for the year were to be in the Top Ten eBird users in my county, and to attempt to take a good photo of each species. I ended up at #6, and I’m happy with the photos I got (a selection of you will …


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25 December 2023

The Greywacke, by Nick Davidson

Just finished a geologically focused book that the readers of this blog might be interested in. It is a history of work on delineating the early part of the Phanerozoic timescale in Wales and Scotland. The majority of the book is about Adam Sedgewick and Roderick Murchison and their close collaboration and increasing divergence and eventual total estrangement as they sought to sort out the boundaries of different periods of …


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1 December 2023

Friday fold: a Massanutten cross-section from a century ago

The Friday fold digs deep into the historical archives for a near-century old illustration of the geology of the Massanutten mountain system in Virginia’s Valley & Ridge geologic province.


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17 November 2023

Friday fold: Floor paver in the Atlanta airport

On my way back to Virginia from Hawaii, I had a three hour layover in the Atlanta airport. There, I spotted this charismatic stone paver on on the terminal floor. It showed folds, and so I snapped a photo, but it also shows plenty more… An annotated copy: Happy Friday, all!


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9 November 2023

Glacial geology of Discovery Park, Seattle

A field trip to examine the glacial geology of Discovery Park in Seattle, Washington, leads Callan to contemplate the nature of expertise — and especially his steep learning curve on an oceanographic cruise.


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7 November 2023

Near-empty seas, near-empty air

Callan is currently at sea aboard the research vessel Thomas G. Thompson, crossing the North Pacific Ocean from Seattle to Honolulu. In this post, he explores a fascinating aspect of life on the high seas: there is shockingly little life! Explore the scant copepods and albatrosses and reflect on life in the oligotrophic open ocean.


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3 November 2023

Friday fold: Neoproterozoic rhyolite (of the Konnarock Formation?)

The Friday fold returns!
Today we join the Virginia Geological Field Conference to look at primary volcanic flow banding in a Neoproterozoic rhyolite, and consider what it might have to tell us about the ancient Snowball Earth glaciations.


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1 November 2023

Four new videos about east coast geology

Hi all! I’ve been putting my energy into video production more than blogging lately, but let me share some of that work with you:


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15 September 2023

Friday fold: Candler Formation

On a birding hike yesterday morning, I found this: This is a little slab of kinked phyllite of the Candler Formation. This metamorphic rock started as mud (and ash) deposited atop the Catoctin Formation, and it was later squeezed and heated during Appalachian mountain-building, encouraging the growth of micas at the expense of clay. A strong differential stress made sure those micas grew in one preferred orientation, and that resulted …


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