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You are browsing the archive for geologic time Archives - Mountain Beltway.

27 March 2019

Timefulness, by Marcia Bjornerud

[Note: this book review was scheduled to run in the July 2019 issue of EARTH magazine, but with the announcement two weeks ago that EARTH was being shuttered, I was notified that nothing contributors or freelancers had written scheduled for after April 2019 would be published, and the rights were returned to me. While that’s disappointing, it frees me up to publish it here instead. Enjoy!] _____________________________________________ Geology is a …

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13 September 2018

A New History of Life, by Peter Ward and Joe Kirschvink

Yesterday, I finished listening to the audiobook version of A New History of Life, by Peter Ward and Joe Kirschvink (2016). This book is only a couple of years old, and takes as its topic ‘the modern perspective’ on life’s long history on Earth, using the latest insights available. It aims to debunk old hypotheses that don’t stand up to new data, and to expand the purview of life’s reign …

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13 May 2018

A Most Improbable Journey, by Walter Alvarez

As mentioned the week before last, Walter Alvarez has a new book out. I’ve read it. It’s good. It’s Alvarez’s take on what he calls “Big History” – the story that spans the cosmos, the Earth, life, and humanity. It’s pretty great for the reasons that Alvarez’s other books are excellent – his voice is calm, appreciative, and patient. His language is accessible and appropriate (though I will grouse that …

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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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30 June 2016

Virtual field trip to Siccar Point, Scotland

Time for another virtual field trip on the Geologist’s Grand Tour of the United Kingdom: the most famous outcrop in the world. Today, we visit Siccar Point, Scotland. You’ve probably already seen photos of this place – they usually look something like this: To those who aren’t familiar, here’s what going on: There are two sets of strata here – and the contact between them is an ancient erosional surface. …

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17 February 2014

A marine incursion in the Hampshire Formation?

I went out last Tuesday to Corridor H, the exemplary new highway cutting through the Valley and Ridge province of eastern West Virginia. Joining me was former student Alan Pitts, a devotee of Corridor H from way back in the early days when we just called it “New Route 55.” The boondoggle highway is now open all the way west to the Allegheny Front, practically into the Canaan Valley. On Tuesday, …

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1 July 2013

Which is older?

Using your relative dating prowess to determine which of these two rock units is older, the schist (dark gray) or the granite (light pink): Click to enlarge Click to enlarge Justify your answer by citing a principle of relative dating.

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2 June 2013

Sidewalk geologic timescales

Saw this educational graffiti on the campus of Carleton College a few weeks ago: Seems like a great way to get students to grasp the relative spans of geologic time.

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27 September 2011

Geologic timescale names

The geologic timescale: Where did those names come from? Here’s some etymological information I share with my Historical Geology students so that the names become meaningful symbols of ideas, rather than simply of bunch of nonsensical gibberish to memorize… Phanerozoic eon – Greek for “visible life” Cenozoic era – Greek for “new life” Quaternary – Latin for “fourth” Holocene – Greek for “entirely new” Pleistocene – Greek for “mostly new” …

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14 September 2011

Is “Tertiary” archaic?

Jack and Drumlin are visiting for the day from their usual home.

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