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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Clickbaiting terror: what it’s like to write viral news after a tragedy

Does the viral news cycle callously capitalise on terrorism, or is it allowing a different audience to access important news and facts?

On a normal day, Alex* will write anywhere between five to ten articles. As a content creator for a large viral news site, they [Alex is speaking under the condition of strict anonymity, meaning their gender will remain unidentified] will churn out multiple 500-word stories on adorable animals, optical illusions, and sex. “People always want to read about sexuality, numbers of sexual partners, porn habits and orgasms,” says Alex. “What is important is making the content easily-digestible and engaging.”

Alex is so proficient at knowing which articles will perform well that they frequently “seek stories that fit a certain template”. Though the word “clickbait” conjures up images of cute cat capers, Alex says political stories that “pander to prejudices” generate a large number of page views for the site. Many viral writers know how to tap into such stories so their takes are shared widely – which explains the remarkably similar headlines atop many internet articles. “This will restore your faith in humanity,” could be one; “This one weird trick will change your life…” another. The most cliché example of this is now so widely mocked that it has fallen out of favour:

You’ll never believe what happened next.

When the world stops because of a tragedy, viral newsrooms don’t. After a terrorist attack such as this week’s Manchester Arena bombing, internet media sites do away with their usual stories. One day, their homepages will be filled with traditional clickbait (“Mum Sickened After Discovery Inside Her Daughter’s Easter Egg”, “This Man’s Blackhead Removal Technique Is A Complete And Utter Gamechanger”) and the next, their clickbait has taken a remarkably more tragic tone (“New Footage Shows Moment Explosion Took Place Inside Manchester Arena”, “Nicki Minaj, Rihanna, Bruno Mars and More React to the Manchester Bombing”).

“When a terrorist event occurs, there’s an initial vacuum for viral news,” explains Alex. Instead of getting reporters on the scene or ringing press officers like a traditional newsroom, Alex says viral news is “conversation-driven” – meaning much of it regurgitates what is said on social media. This can lead to false stories spreading. On Tuesday, multiple viral outlets reported – based on Facebook posts and tweets – that over 50 accompanied children had been led to a nearby Holiday Inn. When BuzzFeed attempted to verify this, a spokesperson for the hotel chain denied the claim.

Yet BuzzFeed is the perfect proof that viral news and serious news can coexist under the same roof. Originally famed for its clickable content, the website is now home to a serious and prominent team of investigative journalists. Yet the site has different journalists on different beats, so that someone writes about politics and someone else about lifestyle or food.

Other organisations have a different approach. Sam* works at another large viral site (not Buzzfeed) where they are responsible for writing across topics; they explains how this works:  

“One minute you're doing something about a tweet a footballer did, the next it's the trailer for a new movie, and then bam, there's a general election being called and you have to jump on it,” they say.

Yet Sam is confident that they cover tragedy correctly. Though they feel viral news previously used to disingenuously “profiteer” off terrorism with loosely related image posts, they say their current outlet works hard to cover tragic news. “It’s not a race to generate traffic,” they say, “We won't post content that we think would generate traffic while people are grieving and in a state of shock, and we're not going to clickbait the headlines to try and manipulate it into that for obvious reasons.”

Sam goes as far as to say that their viral site in fact has higher editorial standards than “some of the big papers”. Those who might find themselves disturbed to see today’s explosions alongside yesterday’s cats will do well to remember that “traditional” journalists do not always have a great reputation for covering tragedy.

At 12pm on Tuesday, Daniel Hett tweeted that over 50 journalists had contacted him since he had posted on the site that his brother, Martyn, was missing after the Manchester attack. Hett claimed two journalists had found his personal mobile phone number, and he uploaded an image of a note a Telegraph reporter had posted through his letterbox. “This cunt found my house. I still don't know if my brother is alive,” read the accompanying caption. Tragically it turned out that Martyn was among the bomber's victims.

Long-established newspapers and magazines can clearly behave just as poorly as any newly formed media company. But although they might not always follow the rules, traditional newspapers do have them. Many writers for viral news sites have no formal ethical or journalistic training, with little guidance provided by their companies, which can cause problems when tragic news breaks.

It remains to be seen whether self-policing will be enough. Though false news has been spread, many of this week’s terror-focused viral news stories do shed light on missing people or raise awareness of how people can donate blood. Many viral news sites also have gigantic Facebook followings that far outstrip those of daily newspapers – meaning they can reach more people. In this way, Sam feels their work is important. Alex, however, is less optimistic.

“My personal view is that viral news does very little to inform people at times like this and that trending reporters probably end up feeling very small about their jobs,” says Alex. “You feel limited by the scope of your flippant style and by what the public is interested in.

“You can end up feeding the most divisive impulses of an angry public if you aren’t careful about what conversations you’re prompting. People switch onto the news around events like this and traffic rises, but ironically it’s probably when trending reporters go most into their shells and into well-worn story formats. It’s not really our time or place, and to try and make it so feels childish.”

Amelia Tait is a technology and digital culture writer at the New Statesman.

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