Posts Tagged ‘earth science’
“The forces which displace continents are the same as those which produce great fold-mountain ranges”*…
Some 240 million years ago, the patch of land that would one day become the National Mall was part of an enormous supercontinent known as Pangea. Encompassing nearly all of Earth’s extant land mass, Pangea bore little resemblance to our contemporary planet. Thanks to a recently released interactive map, however, interested parties can now superimpose the political boundaries of today onto the geographic formations of yesteryear—at least dating back to 750 million years ago.
The results are intriguing: During the Early Triassic Epoch, the National Mall in Washington, D.C., for example, was wedged almost directly adjacent to Mauritania, yet to be separated from the Northwest African country by the vast waters of the Atlantic Ocean.
Ancient Earth, the tool behind this millennia-spanning visualization, is the brainchild of Ian Webster, curator of the world’s largest digital dinosaur database [an old friend of (Roughly) Daily]…
Visualize the changes between the Cryogenian Period and the present: “This Map Lets You Plug in Your Address to See How It’s Changed Over the Past 750 Million Years.”
* Alfred Wegener, the originator of theory of continental drift
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As we go with the flow, we might send rocky birthday greeting to Maurice-Irénée-Marie Gignoux; he was born on this date in 1881. A geologist, he helped chart the stratigraphy of the Mediterranean during the Pliocene Epoch (5.3 to 2.6 million years ago) and the Quaternary Period (from 2.6 million years ago to the present). His work with “fold models” (that allowed playing out the tectonic forces at work in continental drift and in the formation of mountains) led to a deeper understanding of the structure of the Alps.
“We never cease to stand like curious children before the great mystery into which we were born”*…
This animation shows the movement of the north magnetic pole at 10-year intervals from 1970 to 2020. The red and blue lines indicate “declination,” the difference between magnetic north and true north depending on where one is standing; on the green line, a compass would point to true north. Visual by NOAA National Centers for Environmental Information
In scenario planning, one tries to identify the “driving forces”– the social, political, ecological, technical, and economic dynamics afoot– in the environment that are both likely to impact our future materially and outside our control; one then to knits the possible outcomes of those forces into alternative futures, plausible sketches of the opportunities and challenges that one might face.
There is a special class of driving force, what scenario planners call a wild card: a possibility that has relative low probability in the (usually 10 year) time horizon, but that, should it occur, would have massive consequence. Wild cards are often things like major earthquakes or geo-political conflicts… or environmental catastrophes. While one plans for the implications of the scenarios and their defining driving forces, one plans against wild cards; one creates action plans for the scenarios, contingency plans for the wild cards.
As climate change is slowly but surely converting yesterday’s wildcards (sustained droughts, regular, catastrophic wildfires and storms, etc.) into “regular” driving forces, it is perhaps prudent to look at some of the wildest cards that remain…
One day in 1905, the French geophysicist Bernard Brunhes brought back to his lab some rocks he’d unearthed from a freshly cut road near the village of Pont Farin. When he analyzed their magnetic properties, he was astonished at what they showed: Millions of years ago, the Earth’s magnetic poles had been on the opposite sides of the planet. North was south and south was north. The discovery spoke of planetary anarchy. Scientists had no way to explain it.
Today, we know that the poles have changed places hundreds of times, most recently 780,000 years ago. (Sometimes, the poles try to reverse positions but then snap back into place, in what is called an excursion. The last time was about 40,000 years ago.) We also know that when they flip next time, the consequences for the electrical and electronic infrastructure that runs modern civilization will be dire. The question is when that will happen…
The shield that protects the Earth from solar radiation is under attack from within. We can’t prevent it, but we ought to prepare. Learn more at “The Magnetic Field Is Shifting. The Poles May Flip. This Could Get Bad.”
* Albert Einstein
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As we ponder powerlessness, we might recall that it was on this date in 1697 that Isaac Newton received a copy of Johann Bernoulli’s long-standing mathematical challenge, the brachistochrone problem: “To determine the curved line joining two given points, situated at different distances from the horizontal and not in the same vertical line, along which the mobile body, running down by its own weight and starting to move from the upper point, will descend most quickly to the lower point.” (Bernoulli coined the name from Gr. brachistos, shortest; and chronos, time.)
Newton solved it the same day, and forwarded his solution to the Royal Society—anonymously. When Bernoulli read the solution, he shrewdly guessed it was Newton’s work. By legend, he said, “I recognize the lion by his paw.”
Bernoulli and Newton
“Earth is ancient now, but all knowledge is stored up in her”*…
(Roughly) Daily is headed into a brief hiatus, as your correspondent is hitting the highways of his humid homeland. Regular service should resume on April 26. Meantime…
An illustration of the huge waterfalls cascading over the land bridge connecting Britain to Europe
Britain split from mainland Europe to become an island thanks to catastrophe — that might sound political, but in fact it’s geographic. Thousands of years before the UK opted to leave the European Union, a process called Brexit, a different separation occurred. Unlike the political one, it was relatively simple, and probably composed of just two stages.
First, a review of geography: England is separated from the rest of Europe by a body of water called the English Channel; the bit of water where England is closest to France is called the Dover Strait. But the strait wasn’t always there — it was likely created by two major erosion events, according to a study published today in Nature Communications. The first one likely happened around 450,000 years ago, around the same time Neanderthals first appeared in Europe. That’s when huge amounts of water spilled over from a large lake sitting at the edge of a massive ice sheet that stretched from Britain to Scandinavia. The second one may have occurred 160,000 years ago, when catastrophic flooding opened the Dover Strait. When the ice age ended and sea levels rose, water flowed into that gap. Just like that, Britain became an island…
More at “The first Brexit actually happened thousands of years ago.”
* Jeanette Winterson, Weight: The Myth of Atlas and Heracles
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As we cope with separation anxiety, we might spare a thought for Georges-Louis Leclerc, Comte de Buffon; he died on this date in 1788. A naturalist, mathematician, cosmologist, and encyclopédiste, Buffon formulated a crude theory of evolution, and was the first to suggest that the earth might be older than suggested by the Bible: in 1778 he proposed that the Earth was hot at its creation and, judging from the rate of its cooling, calculated its age to be 75,000 years, with life emerging some 40,000 years ago.
In 1739 Buffon was appointed keeper of the Jardin du Roi, a post he occupied until his death. There he worked on the comprehensive work on natural history for which he is remembered, Histoire naturelle, générale et particulière. He began in 1749, and it dominated the rest of his life. It would eventually run to 44 volumes, covering quadrupeds, birds, reptiles and minerals. As Max Ernst remarked, “truly, Buffon was the father of all thought in natural history in the second half of the 18th century.”
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