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You are browsing the archive for August 2018 - Mountain Beltway.

31 August 2018

Friday folds: Rifugio Fontana in the Dolomites

TGIF: “Thank Geology It’s Friday!”
Time for a fold or a dozen – let’s travel to the Italian Dolomites to see some kinky crumpled limestones…

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27 August 2018

Beautiful Swimmers, by William Warner

The subtitle of this wonderful book is “Watermen, Crabs, and the Chesapeake Bay.” It’s an excellent account of crab ecology in the Chesapeake Bay as it stood in the mid-1970s, and simultaneously a sympathetic portrait of the lives of the locals who capture those crabs for sale to the seafood market. The writing is thoughtful and calm, paced very similarly to John McPhee’s writing, rich in quotes from the watermen …

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24 August 2018

Friday fold: Gneiss from Arapaho Pass, Colorado

It’s Friday, and I have another guest Friday fold to share: This one is from my Denver friend Greg Willis, who tells me it’s from near Arapaho Pass, near where we rain-hiked. Ahhhh, yes – a singularly soggy hike up in the Colorado Rockies. I remember it well, and it looks like Greg had better weather on this jaunt! Happy Friday to all!

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22 August 2018

Q&A, episode 5

A reader asks: “What is foliation and what makes it so important to the structure of rock?”
Callan answers with a lot of images of beautifully foliated rocks.

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20 August 2018

Under a Green Sky, by Peter Ward

I’ve got a few books to catch up on from my summer reading. The first is Under a Green Sky (2007), by University of Washington geoscientist Peter Ward. I picked this up because it was referenced in another book I’d read recently: Peter Brannen’s The Ends of the World (2017). (I’ve got a review of that one coming out in a forthcoming issue of EARTH magazine, by the way!) Brannen …

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17 August 2018

Friday folds: Moomaw Reservoir outcrops

Break out your paddle and sunhat. We’re going kayaking on Lake Moomaw, in search of Friday folds…

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16 August 2018

A suite of deformational features in Lancaster limestones

In the Landisville Quarry, Lancaster, Pennsylvania, there is a quarry that cuts into Cambrian limestones. (The exact identity of these limestones is apparently a matter of some dispute, but that’s not going to stop us!) I visited the quarry in June on a field trip offered through the NAGT’s Eastern Section annual meeting. We witnessed multiple varieties of deformation there. First off, there was straight-up brittle extension, resulting in bedding-perpendicular …

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10 August 2018

Friday fold: Gnarly chert from Spy Rock

The Friday fold is an outcrop of folded chert from the Franciscan mĂ©lange in Mendocino County, California. (It should look familiar to anyone who’s ever visited Marin Headlands near San Francisco.)

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6 August 2018

The Invention of Air, by Steven Johnson

This is an interesting book – simultaneously about Enlightenment science, energy flows driving human history, and the boundary-less conception of politics, religion, and science that was embraced by Benjamin Franklin, Thomas Jefferson, and the book’s principal protagonist, Joseph Priestley (and to a lesser, or at least less-well-documented, degree by John Adams).  The discussion begins in the coffeehouses of 1760’s London, where conversation roamed freely and exuberantly  between intellectuals and amateur …

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3 August 2018

Friday fold: a recumbent set of turbidites in the Black Hills

Today we feature a famous recumbent, chevron anticline near Hill City, South Dakota has been featured as a Friday Fold or not, but thought I would give it a go. The rocks are Proterozoic metagreywacke turbidites with 70 complete or partial Bouma sequences. This is believed to be a late (D4) fold in the Black Hills related to upward doming associated with the emplacement of the Harney Peak Granite, which …

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