Meteorite impacts leave behind time-capsules of ecosystems

Glass beads that form inside hot meteors as they fall to Earth capture particles from the atmosphere, creating a kind of permanent record of historic climates.

Meteorite impacts can be very destructive. One that fell in Mexico around 66m years ago created a 180km crater and caused the extinction of dinosaurs while spewing debris and molten rock into the air. Now, in what is a fascinating tale of serendipity, researchers have found that these events don’t entirely destroy all traces of life at the site of impact. Molten rocks can capture and preserve organic matter as they cool down to form glass beads.

When a meteor enters Earth’s atmosphere, the air around the meteor gets very quickly compressed causing it to heat up, scorching everything in its path. Most of the time that is where the story ends, as the meteor burns up in the sky as a “shooting star”. But sometimes it is big enough to reach all the way to the surface and transfer its remaining energy to the ground.

This energy is dissipated, as mild earthquakes, sound shockwaves – but mostly as heat. The heat energy can be so great that it melts rocks on the surface and hurls them up in the atmosphere. Anything that comes in contact with this molten rock would presumably get burnt, leaving nothing but rocky material that cools down in the atmosphere, forming glass beads and tektites (gravel-sized natural glass). This is what City University of New York researcher Kieren Howard assumed, but he was able to show that his assumptions were wrong.

For his PhD, Howard was studying the glass beads and tektites found near the Darwin crater in Tasmania. The 1.2km wide crater was created by a meteorite impact about 800,000 years ago.

The natural glass formed during cooling is (as implied by the term glass) not crystalline. Instead of a regular arrangement of atoms, the atoms inside it are randomly arranged. Howard’s analysis, however, kept showing the presence of crystals. At first, he dismissed this as a problem with the machine or with his method of analysis. But when it kept showing up, as a good scientist, he thought he should ask an expert to look at his data.

“This is unusual,” says Chris Jeynes, a physicist at the University of Surrey. “If there were indeed crystals, then it was the result of uneven cooling, which can occur when something gets trapped inside these glass beads.”

Jeynes used proton-beam analysis, a method to peer inside the glass to reveal its elemental make-up. Inside he found carbon. “Howard had no idea what his samples were, and he was very surprised when I told him,” Jeynes says.

The natural glass formed should contain only silicon, titanium, oxygen and other metallic elements in trace amounts. Detection of carbon meant that there was some organic matter inside. The only hypothesis was that, somehow during the formation of these glass beads, they captured organic matter that was floating in the atmosphere. That organic matter might have already been in the air, but it might also include material thrown up by the impact.

Howard then went to another expert to break open these glass beads and reveal what the carbon-rich matter was. It turned out that it included were cellulose, lignin and other biopolymers. This meant that somehow this matter, which originated from plants, had survived the temperature of more than 500°C, which is what the molten rock would have reached before cooling into a glass bead. Usually these temperatures will break down the organic matter, but clearly it didn’t in this case.

Mark Sephton, a geochemist at Imperial College London, was surprised and pleased: “What the results show is that these glass beads can capture an aliquot of the atmosphere of the planet at impact. It is like a time capsule of that ecosystem.” These results are published in Nature Geoscience.

The implications are enormous. It shows that other meteorite impacts, like the one that wiped out the dinosaurs, could have created such time capsules too. Sephton is now working on finding glass beads from other impact sites to reveal information about Earth’s ancient atmosphere.

This method of analysis means that we could also go looking for similar beads on other planets, like Mars, where meteorite impacts are common. They could also reveal vital information about the past atmosphere of those planets. Maybe they captured organic matter – if it ever existed there.

“We would not know any of this if it wasn’t for Howard,” Jeynes says, adding that Howard’s persistence to find out what “the wrong results” led the researchers to a phenomenon that nobody knew existed.

This article was originally published at The Conversation. Read the original article.

The Conversation

Meteor Crater in Arizona. (Photo: Angle Schatz/Flickr)
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Forget fake news on Facebook – the real filter bubble is you

If people want to receive all their news from a single feed that reinforces their beliefs, there is little that can be done.

It’s Google that vaunts the absurdly optimistic motto “Don’t be evil”, but there are others of Silicon Valley’s techno-nabobs who have equally high-flown moral agendas. Step forward, Mark Zuckerberg of Facebook, who responded this week to the brouhaha surrounding his social media platform’s influence on the US presidential election thus: “We are all blessed to have the ability to make the world better, and we have the responsibility to do it. Let’s go work even harder.”

To which the only possible response – if you’re me – is: “No we aren’t, no we don’t, and I’m going back to my flowery bed to cultivate my garden of inanition.” I mean, where does this guy get off? It’s estimated that a single message from Facebook caused about 340,000 extra voters to pitch up at the polls for the 2010 US congressional elections – while the tech giant actually performed an “experiment”: showing either positive or negative news stories to hundreds of thousands of their members, and so rendering them happier or sadder.

In the past, Facebook employees curating the site’s “trending news” section were apparently told to squash stories that right-wingers might “like”, but in the run-up to the US election the brakes came off and all sorts of fraudulent clickbait was fed to the denizens of the virtual underworld, much – but not all of it – generated by spurious alt-right “news sites”.

Why? Because Facebook doesn’t view itself as a conventional news provider and has no rubric for fact-checking its news content: it can take up to 13 hours for stories about Hillary Clinton eating babies barbecued for her by Barack Obama to be taken down – and in that time Christ knows how many people will have not only given them credence, but also liked or shared them, so passing on the contagion. The result has been something digital analysts describe as a “filter bubble”, a sort of virtual helmet that drops down over your head and ensures that you receive only the sort of news you’re already fit to be imprinted with. Back in the days when everyone read the print edition of the New York Times this sort of manipulation was, it is argued, quite impossible; after all, the US media historically made a fetish of fact-checking, an editorial process that is pretty much unknown in our own press. Why, I’ve published short stories in American magazines and newspapers and had fact-checkers call me up to confirm the veracity of my flights of fancy. No, really.

In psychology, the process by which any given individual colludes in the creation of a personalised “filter bubble” is known as confirmation bias: we’re more inclined to believe the sort of things that validate what we want to believe – and by extension, surely, these are likely to be the sorts of beliefs we want to share with others. It seems to me that the big social media sites, while perhaps blowing up more and bigger filter bubbles, can scarcely be blamed for the confirmation bias. Nor – as yet – have they wreaked the sort of destruction on the world that has burst from the filter bubble known as “Western civilisation” – one that was blown into being by the New York Times, the BBC and all sorts of highly respected media outlets over many decades.

Societies that are both dominant and in the ascendant always imagine their belief systems and the values they enshrine are the best ones. You have only to switch on the radio and hear our politicians blithering on about how they’re going to get both bloodthirsty sides in the Syrian Civil War to behave like pacifist vegetarians in order to see the confirmation bias hard at work.

The Western belief – which has its roots in imperialism, but has bodied forth in the form of liberal humanism – that all is for the best in the world best described by the New York Times’s fact-checkers, is also a sort of filter bubble, haloing almost all of us in its shiny and translucent truth.

Religion? Obviously a good-news feed that many billions of the credulous rely on entirely. Science? Possibly the biggest filter bubble there is in the universe, and one that – if you believe Stephen Hawking – has been inflating since shortly before the Big Bang. After all, any scientific theory is just that: a series of observable (and potentially repeatable) regularities, a bubble of consistency we wander around in, perfectly at ease despite its obvious vulnerability to those little pricks, the unforeseen and the contingent. Let’s face it, what lies behind most people’s beliefs is not facts, but prejudices, and all this carping about algorithms is really the howling of a liberal elite whose own filter bubble has indeed been popped.

A television producer I know once joked that she was considering pitching a reality show to the networks to be called Daily Mail Hate Island. The conceit was that a group of ordinary Britons would be marooned on a desert island where the only news they’d have of the outside world would come in the form of the Daily Mail; viewers would find themselves riveted by watching these benighted folk descend into the barbarism of bigotry as they absorbed ever more factitious twaddle. But as I pointed out to this media innovator, we’re already marooned on Daily Mail Hate Island: it’s called Britain.

If people want to receive all their news from a single feed that constantly and consistently reinforces their beliefs, what are you going to do about it? The current argument is that Facebook’s algorithms reinforce political polarisation, but does anyone really believe better editing on the site will return our troubled present to some prelap­sarian past, let alone carry us forward into a brave new factual future? No, we’re all condemned to collude in the inflation of our own filter bubbles unless we actively seek to challenge every piece of received information, theory, or opinion. And what an exhausting business that would be . . . without the internet.

Will Self is an author and journalist. His books include Umbrella, Shark, The Book of Dave and The Butt. He writes the Madness of Crowds and Real Meals columns for the New Statesman.

This article first appeared in the 24 November 2016 issue of the New Statesman, Blair: out of exile